摘要:

1500 Artalyst, December, 1983, Vol. 108, pp. 1500-1505 Rapid Spectrophotometric Assay of Phenothiazine Drugs in Pharmaceutical Preparations Aly M. Taha, Nawal A. El-Rabbat, Michael E. El-Kommos and lbraheim H. Refat Pharmaceutical Chemistry Department, Faculty of Pharmacy, A ssiut University, A ssiut, Egypt A simple, accurate and rapid method for the quantitative determination of ten phenothiazine drugs in either the pure form or in pharmaceutical formula- tions is proposed. The method is based on the development of pink or violet products with N-bromosuccinimide in a strong sulphuric acid medium. The reaction is suggested to proceed via oxidation of the phenothiazine nucleus into a semiquinonoid radical. The wavelengths of maximum absorption range from 512 to 565nm. Molar absorptivities range from 6 x 103 to 20 x 103 1 mol-l cm-l.A linear correlation was found between absorbance (at the Am=.) and concentration. The resulting colours are well developed within 20-30min and are stable for at least 10h. Results of analyses of pure drugs and their dosage forms by the proposed method are in good agree- ment with those of the official BP 1980 and USP XX procedures. Keywords : Spectrophotometry ; Phenothiazine drug analysis ; N-bromo- succinimide Phenothiazine drugs are extensively used as tranquillisers and antihistaminics in various dosage forms. Several titrimetric,lP2 spectrophotornetri~,~-~ polarographi~,~--~ gas chromato- graphic1°-12 and high-performance liquid chromatographic( HPLC)13-15 methods for the determination of phenothiazine drugs have been described.The official methods generally include non-aqueous titration for bulk drugs and an ultraviolet spectrophotometric method for dosage forms. In this work, a simple, accurate and rapid spectrophotometric method for the determination of phenothiazine drugs using N-bromosuccinimide (NBS) in a strong sulphuric acid medium is proposed. The method is applicable to the determination of bulk drugs and dosage forms. Experimental Apparatus Spectra were recorded on a Zeiss PM2 DL spectrophotometer, using l-cm cells. Samples The following pharmaceutical grade chemicals were donated by different manufacturers and were used as working standards : butaperazine dimaleate and promethazine hydrochloride TABLE I SPECTRAL CHARACTERISTICS OF THE OXIDATION PRODUCTS OF Optimum Optimum final NBS final H,SO, conc.Optimum timelmin PHENOTHIAZINES AND OPTIMUM ANALYTICAL CON'DITIONS FOR THEIR FORMATION Amaxe/ emax. x 10-31 conc., x 10-3, % development Compound nm 1 mol-1 cm-l yo V / V m / v Butaperazine dimaleate . . .. 515 14.58 50 0.6 20 Chlorpromazine hydrochloride . , 525 9.59 50 1.6 30 Fluphenazine hydrochloride . . 543 8.65 40 2.4 30 Methotrimeprazine hydrochloride . . 550 20.62 70 0.8 30 Perazine . . .. .. . . 515 8.95 40 2.4 30 Prochlorperazine maleate . . .. 528 16.89 40 1 .o 30 Pericyazine . . .. .. .. 512 7.74 30 1.6 20 Promethazine hydrochloride . . 565 5.93 60 4.0 20 Thiethylperazine maleate . . .. 550 12.28 50 2.4 20 Thioproperazine mesylate . . .. 516 10.86 40 1 .o 20TAHA, EL-RABBAT, EL-KOMMOS AND REFAT 1501 (Bayer, Germany) ; chlorpromazine hydrochloride, methotrimeprazine hydrochloride, peri- cyazine, prochlorperazine maleate and thioproperazine mesylate (May and Baker, England) ; fluphenazine hydrochloride (Squibb, England) ; perazine (Promonta, Germany) ; and thiethyl- perazine maleate (Swiss Pharma, Egypt).The following commercial pharmaceutical preparations were analysed : tablets [Promacid (Cid) , Moditen (Squibb) , Taxilan (Promonta) and Torecan (Swiss Pharma)] ; suppositories [Promacid (Cid) and Torecan (Swiss Pharma)] : syrups [Expectyl (hdco) and Promantine (Misr)] ; drops [ (Neurazine (Misr) and Taxilan (Promonta)] ; and ampoules [Neurazine (Misr), Promantine (Misr) and Taxilan (Promonta)]. Reagents Chloroform Spectroscopic grade. N-Bromoszcccinivnide solation, 0.002-0.04~0 m/ V .Freshly prepared aqueous solution Sulfihuric acid, 0.1 N . Analytical-reagent grade. Ammonia solation, 6 N. (according to the specific drug) (Merck). Preparation of Sample Solution in distilled water and the volume was made up to 50.0 ml. the addition of a few drops of sulphuric acid. 0.1 mg ml-l. An accurately weighed amount of the phenothiazine or its salt (about 20 mg) was dissolved Insoluble drugs were dissolved by The solution was then diluted to contain Solutions must be freshly prepared. General Assay Procedure A 1.0-ml volume of the sample solution was pipetted into a 5-ml calibrated flask. The optimum volume of sulphuric acid (Table I) was slowly added with continuous stirring in a water-bath, followed by 1.0 ml of NBS solution of the optimum concentration (Table I).The contents were mixed, cooled, diluted to volume with distilled water and left for 20-30 min (Table I). The absorbance was measured at the specific Amax, (Table I) against a reagent blank. Procedure for Tablets Twenty tablets were weighed and finely powdered. An accurately weighed portion of the powder, equivalent to about 20 mg of the phenothiazine salt, was transferred into a 260-ml 0.30 0.25 Q) 5 0.20 e a $ 0.15 0.10 0.05 0 400 450 500 550 600 650 700 Wavelengthlnm Fig. 1. Absorption spectra of the oxidation products of 1, butaperazine dimaleate ; 2, chlor- promazine hydrochloride ; 3, fluphenazine hydro- chloride ; 4, methotrimeprazine hydrochloride ; and 6, perazine. v 400 450 500 550 600 650 700 Wavelengthlnm Fig.2. Absorption spectra of the oxidation products of 1, pericyazine ; 2, prochlorperazine maleate; 3, promethazine hydrochloride; 4, thiethylperazine maleate ; and 5, thiopro- perazine mesylate.1502 TAHA et al. : RAPID SPECTROPHOTOMETRY OF Analyst, Vol. 108 separator, 10 ml of 0.1 N sulphuric acid and 20 ml of distilled water were added and mixed well, The mixture was then rendered alkaline to litmus paper using 6 FI ammonia solution and 1.0 ml, in excess, was added. Extraction with three 30-ml portions of chloroform was then performed and the chloroform extract was collected into a 100-ml calibrated flask and diluted to volume with chloroform. From this solution, 20.0 ml were taken, evaporated to dryness, and the residue was dissolved in 0.1 N sulphuric acid to make 50.0 ml.One millilitre of this solution was used for the general assay procedure. I 4 0.6 8 s 2 LQ f 0.4 0.2 0 450 500 550 600 650 700 Wavelengthlnm Fig. 3. Absorption spectra of the oxidation products of promethazine hydrochloride using different concentrations of N-bromosuccinimide : 4.0 x 6, 5.0 x and 6, 6.0 x m/V of the final assay solution. Concentration of promethazine hydrochloride, 40 pg ml-l of the final assay solution. 1, 1.0 x 10-3; 2, 2.0 x 10-3; 3, 3.0 x 10-3; 4, Procedure for Suppositories Ten suppositories were accurately weighed, broken up into small pieces and mixed well. An accurately weighed portion of the mass, equivalent to 10 mg of the phenothiazine salt, was transferred into a 250-ml separator and 30 ml of 0.1 N sulphuric acid and 30 ml of chloroform were added with shaking until the mass was dissolved.The acid layer was transferred into another 250-ml separator, washed with 30 ml of chloroform, and the washings were combined TABLE I1 STATISTICAL EVALUATION OF THE METHOD Compound Butaperazine dimaleate . . .. Chlorpromazine hydrochloride . . Fluphenazine hydrochloride . . Methotrimeprazine hydrochloride Perazine . . .. .. .. Pericyazine . . .. .. .. Prochlorperazine maleate . . .. Thiethylperazine maleate . . .. Thioproperazine mesylate . , .. Promethazine hydrochloride . . Linear calibration range/ pg ml-l 2.P30 8.0-56 1 &36 4.0-40 4.0-40 4.040 1 2 4 0 2.040 1.6-64 3.2-25 Correlation coefficient, 0.999 7 0.999 8 0.998 6 0.999 8 0.998 6 0.999 8 0.999 8 0.9992 0.9990 0.997 8 Y Intercept, * a 0.000 7 0.004 1 -0.0153 - 0.001 9 - 0.002 3 -0.001 1 0.0000 0.009 6 0.004 1 0.0043 Slope, b 0.022 7 0.026 5 0.0173 0.065 6 0.025 3 0.021 0 0.027 8 0.0179 0.0199 0.024 5 Relative standard deviation 1.21 1.23 2.39 1.19 0.81 1.60 1.28 0.69 2.98 2.94 (a = 10) t, % * 95% confidence limits for the intercept = 0.004 f 0.034.t Relative standard deviation of mean absorbance of the concentration level 16 pg ml-l of each drug in the final assay solution.December, 1983 PHENOTHIAZINES IN PHARMACEUTICAL PREPARATIONS 1503 with the first chloroform layer. The combined chloroform solution was extracted with 10 ml of 0.1 N sulphuric acid, the acid solution was combined with the first acid extract and the chloroform layer was discarded. The mixture was rendered alkaline to litmus paper with 6 N ammonia solution and 1.0 ml, in excess, was added.The chloroform extracts were collected in a 100-ml calibrated flask and diluted to volume with chloroform. From this solution, 40.0 ml were taken, evaporated to dryness and the residue was dissolved in 0.1 N sulphuric acid to make 50.0 ml. One millilitre of this solution was used for the general assay procedure. The solution was then extracted with three 30-ml portions of chloroform. Procedure for Syrups An accurately measured volume of the syrup, equivalent to about 10 mg of the phenothia- zine salt, was transferred into a 250-ml separator. The sample was rendered alkaline to litmus paper with 6 N ammonia solution and 1.0 ml, in excess, was added. The mixture was then extracted with three 30-ml portions of chloroform, the chloroform extracts were collected in a 100-ml calibrated flask and diluted to volume with chloroform. From this solution, 40.0 ml were taken, evaporated to dryness and the residue was dissolved in 0.1 sulphuric acid to make 50.0 ml.One millilitre of this solution was used for the general assay procedure. Procedure for Injections and Drops An accurately measured volume of either the mixture of the contents of five ampoules or a sample of the drops, equivalent to about 80 mg of the phenothiazine drug, was diluted with 0.1 N sulphuric acid to 100.0 ml. A 10-ml volume of this solution was further diluted with 0.1 N sulphuric acid to 100.0 ml and 1.0 ml of this final solution was used for the general assay procedure. TABLE I11 COMPARISON OF THE PROPOSED SPECTROPHOTOMETRIC METHOD WITH OFFICIAL METHODS IN TRE BP 19801' AND USP Xx1' Amount found Official method Sample Chlorpromazine hydrochloride Promacid tablet (25 mg) Promacid suppository (25 mg) Neurazine ampoule (50 mg) Neurazine drops (4%) .. Fluphenazine hydrochloride Moditen tablet (1 mg) . . Prochlorperazine maleate . . Promethazine hydrochloride Promantine ampoule (25 mg) Promantine syrup (0.1 %) . . Expectyl syrup (0.02%) . . Thiethylperazine maleate . . Torecan tablet (6.5 mg) . . Torecan suppository (6.5 mg) . . .. .. .. .. .. ,. .. .. .. .. .. .. .. .. .. Method BP 1980 BP 1980 BP 1980 BP 1980 BP 1980 USP xx USP xx BP 1980 USP xx USP xx USP xx USP xx USP xx USP xx USP xx Result, % 99.83 98.90 98.64 100.63 100.20 100.04 101.04 99.99 99.69 96.79 97.51 102.22 100.46 98.99 96.97 Proposed method, 99.90 99.07 97.66 102.89 99.77 100.37 97.47 100.50 101.60 100.96 100.68 101.20 99.15 96.75 95.00 % I Added/mg 25 25 50 80 10 25 50 60 26 26 Recovery, % 101.35 101.03 99.19 99.68 100.89 103.04 102.08 100.23 96.20 96.80 * Average of three determinations. Results and Discussion Reaction Involved Several oxidising agents have been used for the oxidation of phenothiazines, e.g., iron(II1) salts, cerium(1V) salts, persulphate, hydrogen peroxide and others's In our laboratory, it was found that NBS in a strong sulphuric acid medium oxidises the ten phenothiazines investi- gated to stable pink or violet products with maximum absorption wavelengths in the region of 512-565 nm and apparent molar absorptivities of 6 x 103-20 x lo3 1 mol-l cm-1 (Table I, Figs.1 and 2). The resulting semiquinonoid radical may be formulated as follows:1504 TAHA et al. : RAPID SPECTROPHOTOMETRY OF Analyst, Vol. 108 Optimisation of Variables To develop a quantitative method based on this reaction, a study was conducted to determ- ine the most effective acid species and optimum acid concentration to be used. Sulphuric acid was the most effective acid, compared with hydrochloric, phosphoric, nitric and acetic acids. It was found that the optimum acid concentration for maximum colour intensity differs according to the specific phenothiazine structure and ranged from 30 to 70% V/V of the final assay solution (Table I). It was suggested that high acid concentrations are required because hydrogen ions stabilise the semiquinonoid free radical by decreasing the rate of its disproportionation and subsequent hydrolysi~,~~~~o which may occur according to the following reactions : In general, free-radical decay is more rapid in sulphuric acid solutions of less than 30% V/V.A branched-chain aliphatic moiety yielded the most unstable radical (methotrimeprazine hydrochloride and promethazine hydrochloride needed the highest acid concentration, 70 and 60% VlV). The optimum NBS concentration ranged from 0.6 x 10-3 to 4 x lo5% m/V of the final assay solution (Table I). Smaller or larger amounts of the oxidising agent gave different oxidation products, as shown in Fig. 3 for promethazine hydrochloride as an example. Other expected oxidation productsl8 are + 0 The colours obtained from different phenothiazine derivatives were maximally developed within 20-30 min (Table I) and were stable for at least 10 h.Quantification, Linearity of Beer's Plot, Accuracy and Precision Under the proposed experimental conditions, a linear response between absorbance and concentration was demonstrated over the concentration ranges shown in Table 11. TheDecember, 1983 PHENOTHIAZINES IN PHARMACEUTICAL PREPARATIONS 1505 reproducibility of the method was determined by the analysis of ten replicate samples of each of the phenothiazines investigated, each containing 16 pg ml-l of the drug in the final assay solution. At this concentration level, the calculated standard deviations of mean absorbances are as presented in Table 11.As shown by the results in Table 11, the method is reproducible, accurate and precise. Application to Bulk Drugs and Dosage Forms Results of the analysis of the official phenothiazines in bulk and in the different dosage forms by the proposed method are presented in Table 111. The recorded data showed a good correlation with those of the BP 1980 and USP XX procedures. Moreover, the described procedure has the added advantage of utilising NBS, which is relatively more stable in aqueous solutions than other chromogenic reagents (e.g., hydrogen peroxide) and yields a colourless solution and, accordingly, a colourless blank [cj’., cerium(IV), iron(II1) and bromine]. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. References Gajewska, M., Ciszewska, M., and Goldnik, A., Chem. Anal.(Warsaw), 1978, 23, 503. Nowakowski, K., and Dembinski, B., Acta Pol. Pharm., 1975, 32, 595. Davidson, A. G., J. Pharm. Pharmacol., 1976, 28, 795. Stan, M., Dorneanu, V., and Ghimicescu, C., Talanta, 1977, 24, 140. Gowda, H. S., and Achar, B. N., Indian J. Chem., Sect. A , 1978, 16, 537. Pardo, A., Tomas, F., and Fernandez-Alonso, J. I., An. Quim., 1977, 73, 20. Faith, L., and Vrabel, M., Cesk. Farm., 1976, 25, 288. Teare, F. W., and Yadar, R. N., Can. J. Pharm. Sci., 1978, 13, 69. Cowan, D. A., Methodol. Dev. Biochem., 1976, 5, 193. Kreyenbuhl, B., Joshi, R. K., and Perlia, X., Pharm. Acta Helv., 1978, 53, 139. Laitem, L., Bello, I., and Gaspar, P., J. Chromatogr., 1978, 156, 327. Larsen, N. E., and Naestoft, J., J. Chromatogr., 1975, 109, 259. Gonnet, C., and Rocca, J. L., J. Chromatogr., 1976, 120, 419. Butterfield, A. G., and Sears, R. W., J. Pharm. Sci., 1977, 66. 1117. Landgraf, W. C., in Forrest, I. S . , Carr, C. J., and Usdin, E., Editors, “The Phenothiazines and “British Pharmacopoeia 1980,” HM, Stationery Office, London, 1980. “United States Pharmacopeia XX, Katritzky, A. R., and Boulton, A. J ., “Advances in Heterocyclic Chemistry,” Volume Nine, Academic Tozer, T. N., and Tuck, L. D., J. Pharm. Sci., 1965, 54, 1169. Levy, L., Tozer, T. N., Tuck, L. D., and Loveland, D., J. Med. Chem., 1972, 15, 898. Structurally Related Drugs,” Raven Press, New York, 1974, p. 357. US Pharmacopeial Convention, Rockville, MD, 1980. Press, New York, 1968. Received M u d loth, 1983 Accepted May 10th. 1983

ISSN:0003-2654    

DOI:10.1039/AN9830801500

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

1606 Analyst, December, 1983, VoL 108, p p . 1506-1510 Determination of Ruthenium(ll1) and Palladium( 11) in Mixtures by Derivative Spectrophotometry Basilio Morelli Universitli degli Studi di Bari, Dipartimento di Chimica, Via Amendola 173, 70126-Bari, Italy This paper describes a sensitive method for the determination of ruthenium- (111) and palladium(I1) in mixtures (up to 16 pgml-1 of ruthenium and 4.5 pg ml-1 of palladium) by first and second derivative spectrophotometry. The method is based upon the coloured complexes that both ruthenium and palladium form with 2-thiobarbituric acid. A statistical analysis of the experimental results is presented. Keywords : Ruthenium determination ; palladium determination ; derivative In recent papers,lS2 satisfactory methods for the quantitative determination of bismuth and iron in mixtures with copper by derivative spectrophotometry, using 2-thiobarbituric acid (TBA) as the reagent, have been developed.It is the purpose of this work to demonstrate that first and second derivative spectrophotometry using TBA as the reagent can be a very useful tool for determining ruthenium and palladium in mixtures, without tedious and time-consum- ing separation procedures. spectrophotometry ; 2-thiobarbituric acid Experimental and Results Reagents and Apparatus These were the same as those described previ~usly.l-~ Procedure The procedure is very similar to that used for the determination of palladium (alone) in a water - alcohol medium5; it differs only in the heating of the mixture, i.e., 75 "C for 35 min, 1.2 t! B 9 0 0.8 0.4 360 420 480 540 Wavelength/nm Fig.1. Undifferenti- ated spectrum of a mixture of Ru(II1) - TBA and PdfIIl - TBA com- +0.07 Q) .- c s -e 0.00 2 Q CI .- LL I I +0.007 .- U > .- & s '0 0.000 0 v) -0.007 -I- h2 I I I plexes. 'Ru, 74 pg per -0.07 5 ml; Pd, 13 pg per 5 ml; 300 360 420 480 300 360 420 480 reference, reagent blank. Wavelengthlnm Fig. 2. Graphical measurements for the determination of Pd(I1) by (a) first and (b) second derivative spectrophoto- metry. Pd, 16 pg per 5 ml; Ru, 29 pg per 5 ml; reference, reagent blank.MORELLI 1507 which is a good compromise between the procedures used previously for ruthenium3 and palladium5 determination. Spectrophotometric Measurements Under the experimental conditions, the absorption maxima of the ruthenium - TBA and palladium - TBA complexes lie at 328 and 386 nm,5 respectively. (In the presence of a high concentration of hydrochloric acid5 a shift from 338 to 328 nm was observed for the absorption maximum of the ruthenium - TBA complex.) Because of the large overlap of the two spxtra, the spectrophotomctric determination of ruthenium and palladium, when present in the same solution, is subject to considerable difficulties.However, these can be overcome by the prior distillation of ruthenium3 or, traditionally, by measuring the total absorbance of the mixture at two wavelengths. A more direct approach is possible with derivative spectrophotometry, which is a spectral measurement technique in which the slope of the spectrum, that is the rate of change of absorbance with wavelength, is An undifferentiated sum spectrum (“normal” spectrum) of a mixture of ruthenium - TBA and palladium - TBA complexes, obtained under optimum conditions, is shown in Fig.1. Typical first derivative spectra of two different mixtures of complexes are shown in Figs. 2(a) and 3(a); Figs. 2(b) and 3(b) show the respective second derivative spectra. The derivative spectra were recorded with a slit width of 1 nm, a response time of 4 s and a scanning speed of 120 nm min-l, which were found to be optimum experimental conditions. Unfortunately, both methods are time consuming. +0.25 Q) .- c, P ‘f 0.00 U + r ii -0.25 la) +0.04 Q) .- 4- .- 9 G -0 0.00 s 0 v) -0.04 Wavelengthin rn Fig. 3. Graphical measurements for the determination of Ru(II1) by (a) first and (b) second derivative spectrophotometry.Ru, 18 pg per 5 ml; Pd, 13 pg per 5 ml; reference, reagent blank. The “normal” spectrum shows two peaks at 328 and 386 nm, which correspond to the absorption maxima of the ruthenium - TBA and palladium - TBA complexes, respectively; at these wavelengths the first derivative signal goes through zero and the peaks of the first derivative spectra correspond to the inflection points (points of greatest slope) of the “normal” spectrum. The zero-crossings of the second derivative spectra correspond to the peaks of the first derivative spectra.1608 MORELLI: DETERMINATION OF RU(III) AND Pd(11) Analyst, VOZ. 108 The choice of suitable wavelengths at which to take measurements proportional to ruthen- ium and palladium concentrations for the preparation of calibration graphs followed from an inspection of the spectra in the derivative mode.The measurements taken in the experiments are generally referred to as “graphical measurements8” because they are obtained by means of graphical construction on the chart recording of the spectrum. The types of graphical measurements that were found to be proportional to the palladium concentration are illus- trated in Fig. 2, ie., “peak to peak” measurements8 (h1 and h2) and “base-line” measurements8 (ha). Analogously, the measurements proportional to the ruthenium concentration are shown in Fig. 3: “base-line” measurements (h4) and “peak to peak” measurements (h, and h6). In order to illustrate the types of measurements chosen, we found it convenient to present two examples of both first and second derivative spectra by selecting different recorder scale expansions.Apparently, the method of finding the band heights h,, 12, and h6 in Fig. 3 may involve a certain degree of judgement in the drawing of the tangents. In practice, the geometrical constructions are uniquely defined because of the high reproducibility of the shape of the derivative spectra. This extrapolation technique has been adopted successfully in previous investigations1s2; in this instance, it gave more accurate and reproducible results than a direct measure of the vertical distance between adjacent minima and maxima and maxima and base line, respectively. [Ru3+l/pg ml-’ Fig. 5. Calibration graphs for the Fig.4. Calibration graphs for the deter- determination of Ru(II1) in the mination of Pd(I1) in the presence of Ru(II1) presence of Pd(I1) by first (k4 and k,) by first (h,) and second (h, and k3) derivative and second (k,) derivative spectro- spectrophotometry. Ru, 29 pg per 5 ml. photometry. Pd, 13 pg per 5 ml. TABLE I STATISTICAL ANALYSIS OF THE DETERMINATION OF RUTHENIUM(III) AND PALLADIUM(II) IN MIXTURES WITH TBA BY DERIVATIVE SPECTROPHOTOMETRY Level of significance 9 = 0.01. Type of Angular Detection graphical Correlation coefficient/ limit/ Ion measurement y-intercept coefficient cm-1 pg-1 ml Variance pg ml-l Palladium(I1) . . k, (1st deriv.) -1.2 x 0.999 0.0231 2.7 x lo-’ 0.07 h, (2nd deriv.) 3.5 x 0.998 0.0040 4.1 x lo-* 0.15 h, (2nd deriv.) -1.3 x 0.986 0.0018 1.1 x 10-7 0.56 Ruthenium(II1) .. h4 (1st deriv.) -8.1 x lW4 0.998 0.0154 1.1 x 10-5 0.67 h, (1st deriv.) 2.6 x 0.999 0.0777 4.8 x 0.28 h, (2nd deriv.) 3.5 x 0.999 0.0176 9.0 x lo-, 0.54December, 1983 I N MIXTURES BY DERIVATIVE SPECTROPHOTOMETRY 1509 Calibration Graphs The experimental derivative spectrophotometric measurements bear the same relationship to concentration as do the “normal” spectrophotometric measurements, up to 16 pg ml-l of ruthenium and 4.5 pg ml-l of palladium. Typical examples of working graphs obtained from height (h) measurements for standards containing 29 pg per 5 ml of ruthenium and increasing amounts of palladium and 13 pg per 5 ml of palladium and increasing amounts of ruthenium are shown in Fig. 4 (h,, h, and h3) and in Fig.5 (h4, h, and he), respectively. (The straight lines reported are the best-fit lines by linear regression.) The ordinate values (h) were obtained from the h (in millimetres) measure- ments taken on chart recordings of the spectra and “standardised” as follows2 : Recorder divisions (h mm) x scale expansion Height = 100 mm full scale Obviously, there is a mutual independence between ruthenium and palladium, i.e. , h,, h, and h, and h,, h, and h, are independent of ruthenium and palladium concentrations, respectively. In fact, some h,, h, and h, and h,, h, and h, measurements obtained by using samples with ruthenium and palladium concentrations different from those previously reported (29 pg per 5 ml of ruthenium and 13 pg per 5 ml of palladium) still followed the straight lines shown in Figs.4 and 5, respectively. 60- 50- 40- $ a 30 20 10 Statistical Analysis of Results and Conclusions An objective judgment of the proposed methods and a comparison among them follows by assessing the results of the statistical analysis of experimental data, which is shown in Table I. - - - I I I I vh4 0 1 2 3 4 0 5 10 15 [Pd*+]/pg ml-’ [Ru3+fig mT1 Fig. 6. Variation of confidence limits for the determination of (a) Pd(I1) and (b) Ru(II1) by first (hl, h4 and h5) and second (h2, h, and he) derivative spectrophotometry a t different levels of significance ( p ) in the form of un- certainty (%) on concentration. @, p = 0.01 (99% probability); ., p = 0.05 (95% probability).1510 MORELLI The high values of correlation coefficients and the intercepts on the y-axis (close to zero) indicate the good linearity of all calibration graphs and the conformity to Beer’s law of first and second derivative measurements.Amongst the methods utilised for the determination of palladium, the most sensitive seems to be the first derivative (h,) measurements because the higher value of the angular coefficient compensates largely for the greater scattering of experimental points, i.e., the higher value of variance. Analogously, the detection limit is a minimum for the determination of ruthenium by the first derivative (h5) method. A guide to the level of precision that may be expected from the application of the methods proposed is given by the graphs in Fig. 6(a) and (b), which show the confidence limits for the determination of palladium and ruthenium, respectively, at both p = 0.01 and p = 0.05 levels of significance, in the form of uncertainty (yo) on concentration, i.e., as AC/C y0.2-5 In conclusion, this paper provides a general procedure for the analysis of ruthenium - palladium mixtures; derivative spectrophotometry seems to offer some interesting possibilities for the simultaneous determination of these ions using TBA as a reagent.The accuracy and precision of all the methods presented are acceptable, with the added advantage of speed, simplicity and excellent sensitivity. First derivative would seem to be a little more convenient than second derivative spectrophotometry for the application to routine practical analysis of mixtures of ruthenium and palladium. In particular, h, measurements (for palladium) and 12, measurements (for ruthenium) would seem to be more reliable, because of the higher sensitivity and precision, than other “graphical measurements” methods proposed. References 1. 2 . 3. 4. 5 . 6 . 7 . 8. Morelli, B., Analyst, 1982, 107, 282. Morelli, B., Analyst, 1983, 108, 870. Morelli, B., Analyst, 1983, 108, 386. Morelli, B., Analyst, 1983, 108, 959. Morelli, B., Analyst, 1984, in the press. O’Haver, T. C., Anal. Chem., 1979, 51, 91. O’Haver, T . C., Clin. Chem., 1979, 25, 1548. O’Haver, T. C . , and Green, G. L., Anal. Chem., 1976, 48, 312. Received June 6th, 1983 Accepted July 25th, 1983

ISSN:0003-2654    

DOI:10.1039/AN9830801506

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

Analyst, December, 1983, Vol. 108, pp. 1511-1520 151 1 Initial Studies on the Application of High- performance Liquid Chromatography to Determine Organocopper Speciation in Soi I -pore Waters Leslie Brown,* Stephen J. Haswell, Michael M. Rhead, Peter O’Neill and Keith C. C. Bancroft John Graymore Chemical Laboratory, Defiartment of Environment Sciences, Plymouth Polytechnic, Drake Circus, Plymouth, PL4 8AA The use of reversed-phase high-performance liquid chromatographic tech- niques with molecular- and atomic-spectroscopic detectors to determine organocopper complexes in soil-pore water is described. Polar dissolved organic compounds and associated copper complexes are separated using either a single Hypersil ODS column or two Hypersil ODS columns and a Hamilton PRP 1 column in series.Quantification was achieved using ultra- violet detectors for the organic molecular species and graphite furnace atomic-absorption spectrometry for the copper. Keywords: Polar organocopper complex determinations; high-performance liquid chromatography ; ultraviolet - atomic-absorption spectroscopic detec- tion ; soil-pore waters A satisfactory method of detection for metal speciation in environmental waters is a pre- requisite for the understanding of both metal mobility and its availability to biological sy~tems.l-~ The development of reversed-phase analysis of polar dissolved organic com- pounds (PDOCs) suggested that, with suitable specific detectors, such techniques might afford an insight into organocopper speciation in natural waters. We report the preliminary results detailing the application of molecular- and atomic-spectroscopic techniques to the deter- mination of PDOC - Cu complexes, particularly in soil-pore waters.As well as the high relative molecular mass compounds, such as polysaccharides, peptides, lipids and humic substances, there is a wide range of low relative molecular mass metabolites produced in soils by micro-organisms and plant roots.4 The film of capillary water within soil aggregates and on the surface of soil particles contains relatively high concentrations of potential complexing organic acids associated with the proliferation of micro-organisms in this environment. Bonneau and Souchier5 have reported the presence of citric, malic, lactic and formic acids in soil-pore waters.The low relative molecular mass compounds that are polar and soluble in aqueous solutions are of particular interest, as they are more likely to be directly available to organisms. There are many areas of the UK where copper deficiency in crops, particularly wheat and barley, occurs.6 It has been found that total-copper levels in soils are of little diagnostic value but EDTA (sodium salt) extractions, which are thought to extract organically complexed copper, can be used to indicate copper availability. Knowledge of the specific compounds involved in copper uptake is lacking and the correlation between actual uptake and “Na EDTA extractable” copper is not good.3 The strong chelating properties of low relative molecular mass organic acids and their production by micro-organisms play an important part in the bioweathering of rocks and in the production of fresh soils.7 There have been recent reports that significant amounts of copper are associated with organic species other than those normally described as humic and fulvic acids.8-10 The direct interfacing of high-performance liquid chromatography (HPLC) with ultraviolet molecular absorption and graphite furnace atomic-absorption spectroscopy, as reported in this paper, provides a sensitive method for the separation and quantification of a number of polar organic compounds and the copper associated with them.* Present address : Analytical and Environmental Consultancy Services, Ventonleague House, 15 Wern Fawr Road, Wern Tarw, Pencoed, Nr. Bridgend, Mid Glamorgan.1512 Reagents BROWN et al.: INITIAL STUDIES ON APPLICATION OF Experimental AnaZyst, VoZ. 108 All organic acids and standards were of AnalaR grade. Distilled water. De-ionised, distilled water. HPLC eluent. Orthophosphoric acid, 0.02% V/V in distilled water (pH 2.6). Microbiological assay. Substrates used were potato dextrose agar and nutrient agar. Apparatus A Perkin-Elmer Series 2 liquid chromatograph equipped with an ultraviolet detector (either a Perkin-Elmer LC 75 with scanning facility or a Pye LC UV) set at 215nm was used. This was connected to a Waters U6K injector valve, Perkin-Elmer 023 recorders and either a single column [Hypersil 5-pm octadecylsilane (ODs)] (250mm x 5mm id.) or three columns (two Hypersil5-pm ODS and one Hamilton 10-pm PRP 1) (250 mm x 5 mm i.d.) in series in a constant-temperature (28.5 "C) enclosure.For copper detection either (i) discrete eluate fractions (60 p1) were collected and an aliquot (20 pl) analysed by manual injection into a graphite furnace atomic-absorbtion spectrophotometer (GFAAS) (Instru- ment Laboratory 151 spectrophotometer with an IL 555 electrothermal atomiser), or (ii) the column was interfaced to the GFAAS using a microprocessor-controlled interface based on a previous designll (Fig. 1). The injector consisted of a pneumatic Altex slider injection valve and a solenoid-controlled syringe needle. The syringe needle was made of & in 0.d. 316 stain- less steel. Nitrogen pressure (16 p.s.i.) was used to deliver the sample from the sample loop Eluent Inject injector sample /*: column Valve sample by-pass Valve sample loop N1 GFAAS injector gas Waste Valve injector v Z N 2 G F A A S cooling gas Fig.1. Schematic representation of the micro- processor controlled HPLC - GFAAS interface.December, 1983 HPLC FOR ORGANOCOPPER SPECIATION IN SOIL-PORE WATERS 1513 through the syringe needle into the cuvette. A microprocessor was used to control the injection sequence, including the operation of the Altex valve, door opening and activation of the solenoid to force the needle through the door port into the cuvette. Further details of the design of the injector will be published elsewhere. Table I lists the GFAAS operating conditions. TABLE I GFAAS OPERATING CONDITIONS Temperature programme Ternperaturel'C.. 75 100 350 700 1800 1800 (a) Manual injection, standard operating conditions*- Time/s .. .. 20 25 25 25 0 5 (b) Direct interfacing conditionst- Ternperaturel'C.. 175 200 300 1000 1800 1800 * Wavelength, 324.7 nm; band pass, 1 nm; injection volume, 20 pl, Wavelength, 324.7 nm; band pass, 1 nm; Altex injection value; nitrogen injection pressure, 16 p.s.i. ; temperature for initiation of injection procedure, 250 "C; sample loop injection volume, 76 pl. Time/s . . .. 5 0 10 10 0 5 Procedure Sample preparation Microbial activity can cause rapid changes in the composition of the PDOCs after collection and during storage. All samples were filtered immediately (Millipore Swinnex fitted with Whatman WCN filters, 0.45 pm) to reduce microbial activity. Storage for periods of 24 h in a refrigerator (4 "C) showed no obvious compositional changes for the samples studied, but storage for longer than 48 h is not recommended.Acidification of collected samples will cause dissociation of many PDOC - Cu complexes and was therefore not used. For soil samples, on-site centrifugation (typically 2000 g for 60 s) was used to extract the pore water, this being completed as rapidly as possible after core collection (Le., within minutes). Selection of GFA AS operating conditions When GFAAS determinations were carried out manually on collected eluate fractions, standard operating conditions were used [Table l ( a ) ] . The direct interfacing of the HPLC - GFAAS systems required both a reduction in the HPLC flow-rate (to 0.1 ml min-l) and an increase in eluate volume injected into the GFAAS to minimise the amount of unanalysed 50 100 150 200 250 300 Injection temperaturePC Fig.2. Absorption signals for 100 pl (5 ng) of copper solution injected via the interface into a cuvette at various initial wa1.l tempera- tures.1514 BROWN d a/?. : INITIAL STUDIES ON APPLICATION OF Artahst, VOL?. 108 eluate. The operating conditions used are given in Table I@). The injection of eluate into the atomiser at elevated temperatures allowed greater volumes (up to 100 pl, if required) to be injected, with consequent increase in sensitivity, and reduction in analysis cycle time from 160 to 90 s. Additional nitrogen cooling of the graphite cuvette was incorporated into the system and this further reduced the cycle time to 50 s. The temperature of commencement of the injection cycle affected the size of the absorption signal (Fig.2). An injection pro- cedure commencing at 250 "C was used during this study. The introduction of the sample by pressurised nitrogen appears to give instantaneous drying with no evidence of splattering at the nitrogen-injection pressure used. With copper nitrate fed into the sample loop by means of a peristaltic pump the limit of detection for copper was determined to be 0.4pgl-1 and the calibration graph was linear up to 60 pg 1-l. Higher gas pressures do cause this problem. Results and Discussion With regard to the chromatographic resolution of PDOC - Cu complexes it was considered that the technique utilised would need to be able to maintain the integrity of the sample and allow simultaneous assessment of both a variety of groups of compounds (carboxylic acids, amino acids, etc.) and the presence of any metal complexes with such compounds.Gas and gas - liquid (GC and GLC) techniques and HPLC techniques requiring ion exclusion, ion exchange or pre-column derivatisations do, by their nature, alter the composition of the sample and thus could not be applied to metal-speciation studies. Reversed-phase HPLC using an ODS stationary phase offered the potential for analysis of a wide variety of polar organic and organometallic compounds and was therefore chosen. Reversed-phase columns will retain polar compounds most effectively when their ionisation is suppressed. As many of the polar organic ligands present in pore waters are acidic, e.g., citric acid, the eluent system chosen to suppress ionisation was also acidic (0.02% V/V orthophosphoric acid, pH 2.6).The relative slowness of the GFAAS detection system reduced the rate of eluate analysis to approximately 6 ml h-l. The isocratic elution with orthophosphoric acid was suitable for certain PDOCs up to citric acid, Table 11. The slower TABLE I1 RETENTION VOLUMES OF POLAR DISSOLVED ORGANIC COMPOUNDS ON SINGLE COLUMN HYPERSIL 5-pm ODS SYSTEM WITH 0.02% V/V ORTHOPHOSPHORIC ACID 25 other compounds had longer retention volumes. Organic compound Oxalic acid .. .. .. Glucuronic acid . . .. .. Cystine . . .. .. .. 2-Ketoglutamic acid . . .. Pyruvic acid . . .. .. Tartaric acid . . .. .. Glycine . . .. .. .. Urea . . .. .. .. Hydroxyproline . . .. . .Allantoin . . .. .. .. Glutamine .. .. .. Retention volume/ml <2.65 ~ 2 . 6 5 <2.65 <2.65 <2.65 <2.65 (2.65 ~ 2 . 6 5 <2.65 2.70 2.75 Organic compound Glycollic acid . . .. .. Cysteine . . .. .. .. Formic acid . . .. .. Citralline . . .. .. .. a-Aminobutyric acid . . * . Malic acid . . .. .. .. Malonic acid . . .. .. Oxoglutaric acid .. .. Lactic acid .. . . .. Citric acid .. .. .. Retention volume/ml 2.75 2.80 3.00 3.20 3.50 3.60 3.70 3.70 4.00 4.40 elution of the PDOCs with longer retention times than citric acid would have required analysis times of greater than 7 h. A less acidic eluent was utilised for these less polar compounds. Ammonium formate solution (0.01 M, pH 6.1) was found to be suitable because it gave a reduced signal to noise ratio for GFAAS analysis as compared with the other chromatographically suitable eluents tested, i.e., combined solutions of sodium dihydrogen phosphate (0.01 M) - disodium hydrogen phosphate (0.01 M) (pH 6.1) and ammonium phos- phate solution (0.01 M) (pH 6.1).However, as no significant amounts of copper were deter- mined with the later eluting compounds, only the use of the orthophosphoric acid eluting system is described in this paper.December, 1983 HPLC FOR ORGANOCOPPER SPECIATION IN SOIL-PORE WATERS J 1515 0 2 4 (b) B A ( C) B A I C + 0 1 2 3 4 5 6 0 3 6 9 1 2 1 5 1 8 Volume of orthophosphoric acid/ml Fig. 3. Separation characteristics of various PDOCs using a 0.02% V/V orthophosphoric acid elution system with (a) a single Hypersil 5-pm ODS column with an eluent flow-rate of 2 ml min-l; (b) a single Hypersil 5-pm ODS column with an eluent flow-rate of 0.1 ml min-l; (c) two Hypersil 5-pm ODs columns in series with one Hamilton PRP 10-pm column at 28.5 "C with a flow-rate of 1 ml min-l.A, Allantoin; B, formic acid; C, malic acid; D, lactic acid; E, citric acid. The use of a single Hypersil ODS column at the higher flow-rates (2 ml min-1) gave some separation of the PDOCs [Fig. 3 ( a ) ] , but the resolution was poor. Better resolution was obtained [Fig. 3(b) J when the eluent flow-rate was reduced to a value (0.1 ml min-l) suitable for use with the GFAAS detection system. The best separation of the PDOCs [Fig. 3(c)] was attained with the three-column system, using two Hypersil ODS columns in series, followed by a Hamilton PRP 1 column held at 28.5 "C.This three-column system was not suitable for interfacing with the GFAAS because the longer retention times would extend the time for a single analysis to nearly 4 h involving over 250 injections compared with about 1 h with about 70 injections using a single column. The retention volumes for a number of PDOCs on the single column system are given in Table 11. Those compounds whose TABLE I11 RETENTION VOLUMES AND DETECTION LIMITS OF SOME POLAR DISSOLVED ORGANIC COMPOUNDS USING TWO HYPERSIL 5-pm ODS COLUMNS AND A HAMILTON 10-pm PRP 1 COLUMN IN SERIES Conditions : 28.5 "C with 0.02% V/ V orthophosphoric acid, flow-rate 1 ml min-l. Organic compound volume/ml (100-pl injection) /ng Retention Detection limit Allantoin . . . . 12.0 1 Formic acid .. . . 13.5 5 Malic acid . . . . 15.0 5 Lactic acid . . . . 16.8 100 Citric acid . . . . 21.0 1001516 BROWN et al. : INITIAL STUDIES ON APPLICATION OF Analyst, VoZ, 108 retention volumes were greater than 4.4 ml were not subsequently considered as the HPLC - GFAAS interface was not operated to investigate their presence. Greater resolution was obtained with the three-column system, Table 111, and this was used to confirm the presence and concentration of some compounds. Again, only the compounds of particular interest in this paper are given in Table I11 and fuller details of all compounds which can be resolved will be published separately. The three-column system was especially useful for acids that were present in amounts close to or below the detection limit for the single-column system.Having confirmed the separation achieved by running mixtures of standard compounds, soil-pore waters were examined. One soil-pore water [Fig. 4(a)] contained five recognisable 50 r 10 0 1 2 3 4 5 Volume of orthop 1 2 3 4 5 lhosphoric acid/m I Fig. 4. UV absorbance signals of various PDOCs separated from a soil pore water on a Hypersil 5-pm ODS column with a 0.02yo V / V orthophosphoric acid elution system (a) with identification and quantification by co-injections of (b) citric acid (1 p g ) (E); (c) formic acid (1 pg) (B) and lactic acid (1 pg) (D); and (a) allantoin (0.05 pg) (A) and malic acid (0.3 p g ) (C). PDOCs when run on the single-column system. These compounds were identified on the basis of their retention volumes, Table 11.Standard solutions of pairs of the proposed compounds were added to aliquots of the pore water. The coincidence of the respective peaks [Fig. 4(b), (c) and (43 confirmed the presence of the compounds and allowed them to be quantified. Repeat runs carried out on the three-column system gave similar results usually agreeing to within *ZO%. However, there were a number of instances where the quantification of some individual PDOCs based on the single-column system deviated substantially from that obtained using three columns. The superior qualities of the three- column system with respect to chromatographic separation made the quantification more precise and its use is essential for the determination of PDOCs.December, 1983 HPLC FOR ORGANOCOPPER SPECIATION IN SOIL-PORE WATERS 1517 Initial development of the use of the GFAAS as an element-specific detector involved fraction collection of the HPLC column eluate.In order to ensure that adequate resolution of the peaks was obtained, and to reduce the dilution effects from non-copper containing eluate, 6O-pl fractions were collected. Aliquots of 2 0 4 of these were injected manually into the GFAAS. This procedure was used for a study of the stability of copper(I1) - citric acid complexes when passed through a Hypersil ODS column in the presence of ortho- phosphoric acid (Fig. 5 ) . A series of mixtures were eluted and comparison of the ultraviolet and GFAAS results indicates that the addition of citric acid to a copper(I1) solution will cause the formation of a copper(I1) - citrate complex [Fig.5 ( b ) and ( c ) ] . Calculations based on the concentration, pH and copper stability constants with the orthosphosphoric acid eluent system indicated that citric acid would form copper complexes that would remain substantially undissociated during column chromatography. It was assumed that instant equilibria occurred, and no allowance was made for possible stationary-phase adsorption. These assumptions appeared to be justified by the formal agreement between the theoretical stability and the actual stability under the HPLC separation conditions used. r t 25 20 U J 2 15 8 'c :: 10 2 UI 5 I I , I 0 2 4 6 0 2 4 6 0 2 4 6 0 2 4 6 Volume of orthophosphoric acid/ml Fig. 6. UV absorbance and copper distribution patterns of copper - citrate mixtures with separation on a Hypersil 6-pm ODS column using 0.02% V/V orthophosphoric acid with (a) citric acid (10 mg 1-l); (b) copper nitrate (1 mg 1-l) ; (c) copper nitrate (1 mg 1-l) - citric acid (10 mg F), pH 7; (d) copper nitrate (1 mg 1-l) - citric acid (10 mg l-l), pH 1. Aliquots (60 pl) of column eluate were manually collected with fractions (20 pl) of these aliquots analysed for copper by GFAAS.The acidification of the copper(I1) - citric acid mixture with hydrochloric acid, as might be carried out to preserve an environmental sample after collection, gave no sign of the presence of the complex [Fig. 5 ( d ) ] . This illustrates the importance of the use of minimum pre-analysis preservation treatment when attempting speciation studies.In all subsequent work the microprocessor-controlled interface between the HPLC - ultra- violet detector and the GFAAS was used.1518 BROWN et al. : INITIAL STUDIES ON APPLICATION OF Analyst, VOl. 108 The further analysis of larger numbers of soil-pore waters using the single-column HPLC system interfaced with GFAAS showed that the copper was not always associated with the same PDOCs in the same proportions (Figs. 6 and 7). In the majority of pore waters association of the copper with citric acid and neighbouring eluting compounds was found [Fig. 6(a)]. The complexing effect of citric acid was emphasised by adding a mixture of copper(I1) nitrate and citric acid to the pore water [Fig. 6 ( b ) ] . The proportion of copper associated with the solvent front, inorganic and highly polar species, was 16% before the standard addition, with the remaining 84% of the copper being associated with the citric acid peak.In the original pore water the total copper content was 43 pg 1-1 as determined 2 1 [5) a2 P P V . Y- fn r" 8 4 0 h- 1 2 3 4 5 6 Volume of orthophosphoric acid/ml 70 60 50 40 30 2 ? m 0 II 20 8 lo 5 s1 E fn +.' .- 0 - m (v r w 50 0 tu 2 40 2 9 30 20 10 Fig. 6. UV absorbance and copper distribution patterns of a soil pore water using (a) a Hypersil 5-pm ODS column with a 0.02% V/V orthophosphoric acid elution system with flow-rate 0.1 mlmin-l and the HPLC - GFAAS interface; (b) an aliquot of the same pore water spiked with 60 ng of copper and 3 pg of citric acid.December, 1983 HPLC FOR ORGANOCOPPER SPECIATION IN SOIL-PORE WATERS 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Volume of orthophosphoric acid/ml Fig.7 . Distribution of copper in various pore waters [(a), (b) and (c), collected from three sites in the Tamar Valley] using UV and the HPLC - GFAAS interface with separation on a Hypersil 5-pm ODS column with 0.02% V / V orthophosphoric acid elution system with eluent flow-rate of 0.1 ml min-l. by direct injection into the GFAAS and 42 pg 1-1 as determined by summation of the copper peaks after HPLC separation [Fig. 6 ( a ) ] . In the latter, a correction to take account of the volume of eluate not injected into the GFAAS was applied, and this raised the measured value of 39 pg 1-1 to 42 pg 1-l. When 50 ng of copper(I1) ion and 3 pg of citric acid were added to an aliquot of soil-pore water [Fig.6(b)] the total copper content was determined to be 65pg (theoretical value 63 pg). This was equivalent to a concentration of 217 pgl-1 compared with a calculated value, owing to addition, of 209 pg l-l, with similar percentage distributions between the solvent front and citric acid peaks, as were obtained before the standard addition. A number of the more extreme distributions found in the soil-pore waters examined are illustrated (Fig. 7) and the copper levels are quantified in Table IV. Citric acid - copper TABLE IV AMOUNT OF COPPER IN SOIL-PORE WATERS AS DETERMINED BY GFAAS AFTER HPLC SEPARATION USING A HYPERSIL 5-pm ODS COLUMN Eluent 0.02% V / V orthophosphoric acid, flow-rate 0.1 ml min-l; see Fig. 7 for chromatographic separations.Amount of copper in soil-pore water r 1 Sample 7(a)*/ Percentage Sample 7(b)*/ Percentage Sample 7(c)*/ Percentage HPLC peak r-cg 1-1 of total r g I-' of total CLg 1-1 of total Solvent front . . .. 64 63 13 21 13 30 2-Ketoglutamic acid - cystine . . .. 5 12 Allantoin , . .. 2 6 Formic acid . . .. 19 30 Malic acid . . .. 5 4 20 32 16 37 Lactic acid . . . . 13 11 Citric acid . . .. 39 32 11 17 7 16 * Samples 7(a), (b) and (c) are the samples used as illustrations in Fig. 7(a), (b) and (G). association was found in all the samples but the association of copper with allantoin, formic and lactic acids occurred rarely. Malic acid was second only to citric acid in the number of samples that showed association between it and copper. The unfiltered pore waters were examined for the presence of microorganisms that might produce the organic acids found and microorganisms with these properties (genus Bacillus and Pseudomonas) were identified.121520 The methods we have described are proving very useful in our studies of the factors that affect PDOC - metal associations in the soils of the Tamar Valley area.Promising results are being obtained with metals other than copper and also in a study of the effects of adding sewage sludge to pasture land. As well as being used to study soil-pore waters the Hypersil ODS HPLC - GFAAS system can be applied to other natural and polluted water systems. BROWN, HASWELL, RHEAD, O’NEILL AND BANCROFT The authors thank Mr. A. Hopkin for help in the design and construction of the HPLC - GFAAS interface unit. In addition they thank Dr. L. Ebdon and Dr. P. Jones, Plymouth Polytechnic, and Dr. J. J. Cleary, Dr. R. F. C. Mantoura and Dr. A. Nelson, Institute for Marine Environmental Research, Plymouth, for their assistance in the preparation of this paper. 1. 2. 3. 4. 6. 6. 7. 8. 9. 10. 11. 12. References Stevenson, F. J., and Ardakani, M. S . , in Mortvedt, J. J., Giordano, P. M., and Lindsay, W. L., Editors, “Micronutrients in Agriculture,” Soil Science of America, Inc., Madison, WI, 1972, p. 79. Van Loon, J. C., Anal. Chem., 1979, 51, 1139A. Goodman, B. A., and Lineham, D. J., in Harley, J. L., and Scott Russell, R., Editors, “The Soil - Zvyaginsev, D. C., Bull. Ecol. Res. Com. (Stockholm), 1973, 17, 61. Bonneau, M., and Souchier, B., “Constituents and Properties of Soils,” Academic Press, London, Caldwell, T. H., “A.D.A.S. Advisory Paper No. 17,” Ministry of Agriculture, Fisheries and Food, Dacey, P. W., Wakerley, D. S., and Le Roux, N. W., Report No. LR 380 (ME), Warren Spring Hart, B. T., and Davies, S. H. R., Estuarine, Coastal Shelf Sci., 1981, 12, 353. Mills, G. L., Hanson, A. K., Quinn, J . E., Lammela, W. R., and Chasteen, N. D., Mar. Chem., 1982, Lee, J., Water Res., 1981, 15, 507. Stockton, R. A., and Irgolic, K. J., Int. J . Environ. Anal. Chem., 1979, 6, 313. Collins, C. H., “Microbial Methods,” Butterworth, London, 1967. Root Interface,” Academic Press, London, 1979, p. 68. 1982. London, HM Stationery Office, 1976, 12. Laboratory, Stevenage, 1981. 11, 355. Received August 2nd, 1982 Accepted July 26th, 1983

ISSN:0003-2654    

DOI:10.1039/AN9830801511

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

Analyst, December, 1983, Vol. 108, pp. 1521-1524 1521 Analytical Methods Committee MEDICINAL ADDITIVES IN ANIMAL FEEDS SUB-COMMITTEE (A) Determination of Ronidazole in Animal Feeds by High-performance Liquid Chromatography Keywords : Ronidazole determination ; high-performance liquid chromato- graphy ; animal feeds The Analytical Methods Committee has received and has approved for publication the follow- ing Report from its Medicinal Additives in Animal Feeds Sub-committee (A). Report The constitution of the Sub-committee responsible for the preparation of this Report was Mr. J. Markland (Chairman until March 1979), Mr. R. S. Hatfull (Chairman from March 1979), Mr. R. J. Anderson, Mr. G. C. Buddle, Mr. A. G. Croft, Dr. N. T. Crosby (from July 1981), Mr. R. J. Davies (from March 1979), Mr.R. Fawcett (until March 1979), Mr. J. R. Harris (until July 1981), Mr. G. Kitson, Mr. G. R. Merson (from October 1979), Mr. D. H. Mitchell (until October 1980), with (the late) Dr. N. W. Hanson (until August 1979) and Mr. J. J. Wilson (from September 1979) as Secretaries. Introduction Ronidazole [ (l-methyl-5-nitroimidazol-2-yl)methyl carbamate] is used in poultry feeds for the control and treatment of blackhead; it is also used in pig feeds for the control and treat- ment of dysentery and as a growth-promoting agent. The normal level of inclusion of the drug in a feed is between 60 and 120 mg kg-l. Methods for its determination by spectrophotometryl and by gas - liquid chromatography (GLC)2J have been published and the Sub-committee was asked to examine a method for its determination by high-performance liquid chromatography (HPLC) , which had been proposed by the German delegate to the EEC Committee of Experts on the Determinaion of Cocci- diostats.The method as received was, substantially, as given in the Appendix. Experimental and Results In a preliminary trial of the method one member took a sample of blank feed and medicated it with 60 mg kg-l of ronidazole. A 10-g mass of sample was extracted with 100 ml of methanol as described in the Appendix. A 50-ml volume of the extract was then put on to the chromatography column, the first 15-20 ml of eluate were discarded and the next 25 ml collected; 20ml of this portion were evaporated to small volume under nitrogen, and then diluted to exactly 1 ml with methanol. This solution was mixed with 10 ml of carbon tetra- chloride and 9 ml of water, shaken for 5 min and centrifuged for 3 min as described under Procedure.Volumes of 20 p1 of the aqueous layer were injected into the HPLC column. A 63.8 mg k g l amount of ronidazole was found, which corresponded to a recovery of 106.3%. Another member used a 10 cm x 4 mm HPLC column and a 70 + 30 methanol - water solution. The initial extraction was carried out using 50 ml of methanol and the volumes of carbon tetrachloride and water were reduced to 10 and 8 ml, respectively. A recovery of 83% was obtained, based on the measurement of the height of the ronidazole peak. Following these preliminary trials, samples of three feeds were circulated to the Sub- Committee members; these were (A) an unmedicated mixed poultry feed; (B) feed A medicated with an unknown amount of ronidazole, which members were told was in the range 60-100 mg k g l ; and (C) a medicated feed similar to (B), which had been formed into pellets.These samples were analysed according to the Procedure given in the Appendix and the results are given in Table I. The actual ronidazole content of samples (B) and (C) was 60 mg k g l .1522 ANALYTICAL METHODS COMMITTEE : DETERMINATION Analyst, VoZ. 108 TABLE I RESULTS FOR ANALYSIS OF FEED SAMPLES A-C Ronidazole in Ronidazole in Ronidazole in sample A/mg kg-l sample B/mg kg-1 sample C/mg kg-1 Recovery, - Recovery, Single && Single Single Laboratory values Average values Average yo values Average yo A B C D E F G Ht IS J K L M N 0 P Q R .... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Mean . . . . <0.5 <0.5 . . 0.8 0.8 . . N.d.* .. <15 .. 0 0 . . N.d. . . N.d. . . <2.0 <2.0 .. 0 0 . . 2.3 1.6 . . 0.9 1 .o . . N.d. .. 0 0 .. 0 0 . . N.d. . . N.d. .. 0 0 .. 0 0 C0.5 0.8 N.d. < 15 0 N.d. N.d. <2.0 0 1.95 0.95 N.d. 0 0 N.d. N.d. 0 0 .. 59.9 59.2 58.4 55.2 55.6 56.0 60.7 60.9 61.1 61.8 60.9 60.0 68.9 71.3 71.9 73.2 62.4 61.1 59.7 61.4 60.4 59.4 56.9 56.1 55.3 55.0 56.0 57.0 55.1 58.1 61.1 61.5 61.7 61.9 58.9 58.9 59.7 58.7 57.6 64.6 63.6 62.6 57.0 59.0 61.0 56.0 54.5 53.0 66.0 64.0 62.0 62.1 61.9 61.6 60.19 98.7 92.7 101.5 101.5 118.5 101.8 100.7 93.5 93.3 96.8 102.8 98.2 97.8 106.0 98.3 90.8 106.7 103.2 65.92 Max. value . . .. .. . . 73.2 68.0 Min.value . . .. .. . . 53.0 52.0 Standard deviation .. . . f3.98 f4.16 Coefficient of variation . . . . f6.61y0 &7.06% Number (n) . . .. .. . . 18 18 56.5 57.3 56.0 54.4 61.1 60.7 58.1 57.7 66.2 66.1 71.6 63.2 64.0 58.8 55.6 55.7 55.6 53.5 56.5 56.8 59.9 55.2 55.6 57.6 57.8 61.9 58.8 61.3 62.9 60.0 60.0 52.0 52.0 61.0 59.0 65.1 66.3 56.9 55.2 60.9 57.9 68.0 63.6 57.2 55.7 55.0 58.4 55.4 57.7 60.4 62.1 60.0 52.0 60.0 65.7 94.8 92.0 101.5 96.5 113.3 106.0 95.3 92.8 91.7 97.3 92.3 96.2 100.7 103.5 100.0 86.7 100.0 109.8 * N.d., not detected. t By GLC: sample B, 56.9; sample C, 55.7 mg kg-l. $ By polarography: sample B, 54.8; sample C, 52.8 mg k g l .December, 1983 OF RONIDAZOLE IN ANIMAL FEEDS BY HPLC 1523 Sample C was crushed using a pestle and mortar before the amount required for analysis was weighed out.Laboratories K and L based their results on measurements of peak height, and they also considered that a shorter column could be used in place of the 30-cm column specified in the method. Laboratory K also recommended the use of 8 + 2 methanol - water in place of the 9 + 1 mixture as this gave a shorter retention time. This laboratory medicated a portion of sample A with 60 mg k g l of ronidazole and obtained a recovery of 102%. Labora- tory H also carried out determinations by GLC and laboratory I by a polarographic method; these results are included as footnotes to Table I. Laboratories J, K and L were members of the Sub-committee; all other results were obtained in the laboratories of other members of the EEC Committee of Experts on the Determination of Coccidiostats.They are included in this report by kind permission of the Chairman, Mme. Dormal van den Bruel. The Analytical Methods Committee recommends the use of the method given in the Appendix for the determination of ronidazole in animal feedingstuffs. APPENDIX Determination of Ronidazole in Animal Feedingstuffs The method is for the determination of ronidazole in animal feedingstuffs. Purpose and Scope Principle Ronidazole is extracted from the sample with hot methanol. The extract is purified on a combined Florisil - alumina column and by partition between carbon tetrachloride and methanol - water. Ronidazole is determined in an aliquot of the aqueous phase by means of reversed-phase high-performance liquid chromatography (HPLC) .Reagents Methanol. Water - methanol, 9 + 1 V/V. Florisil. Active basic aluminium oxide 90. For column chromatography, activity grade I (Merck, No. 1076). Ronidazole. Standard substance. Stock standard solution. Weigh to the nearest 0.1 mg, 30 mg of ronidazole into a 100-ml calibrated flask, dissolve in methanol, under gentle heating if necessary, make up to the mark with methanol and mix. Working standard solution. Transfer by pipette 1 O m l of stock standard solution into a 100-ml calibrated flask, make up to the mark with water and mix. Transfer 10 ml of this solution into a 100-ml calibrated flask, make up to the mark with water - methanol solution (9 + 1) and mix. Place 10 ml of this solution in a 50-ml calibrated flask, dilute to the mark with water - methanol solution and mix.A 1-ml volume of this working standard solution contains 0.6 pg of ronidazole. Apparatus For column chromatography (Merck, No. 12518). Carbon tetrachloride. Analytical-reagent grade. Heated magnetic stirrer. Centrifige. High-performance liquid chromatograph with high-pressure column. Column length 30 cm, i.d. 4.0 mm, packed with LiChrosorb RF-8 10 pm, with variable wavelength ultraviolet detector and recorder. Glass chromatography column. Length 30 cm, i.d. 10 mm. Flat-bottomed $ask. Volume 250 ml with ground-glass neck and reflux condenser. Procedure Extraction Weigh to the nearest 10 mg an amount of the finely divided sample, containing about 0.6 mg of ronidazole (e.g., 10 g where the ronidazole content is 60 mg kg-l), and place this in a1524 ANALYTICAL METHODS COMMITTEE 250-ml flat-bottomed flask.Add 100.0 ml of methanol, attach the flask to a reflux condenser, heat on the magnetic stirrer to boiling-point and boil under reflux for 30 min. Allow to cool and filter. Pu ri’cation Plug the lower end of the chromatographic column with glass-wool and pack 3 g of alu- minium oxide into the column by lightly tapping the latter on a soft base. Then add 2 g of Florisil and tap the column again. Place about 20 ml of the clear filtrate (obtained as under Extraction) on the prepared column. Discard the first 9 ml of the eluate and collect the subsequent 2.5 ml. Mix exactly 2.0 ml of this with 20 ml of carbon tetrachloride in a vessel that can be stoppered, add 18.0 ml of water, shake vigorously for at least 5 min and then centrifuge for 3 min. Use an aliquot of the clear aqueous phase for HPLC. High-performance liqNid chromatography Place 0.5 ml of the working standard solution on the high-pressure column via the input slide and elute with water - methanol (9 + 1) at a flow-rate of 1.20 ml min-l. Measure the absorbance of the eluate at 308 nm with an ultraviolet detector in a flow-through cuvette. Record on the recorder and measure the area of the peak. When all of the ronidazole standard has eluted from the column put 0.5 ml of the aqueous sample solution on to the column and measure similarly. Calculation equation : Calculate the ronidazole content of the sample in milligrams per kilogram using the following A x 600 B x E Ronidazole content = where A is the area of the ronidazole peak for the sample; B is the area of the ronidazole peak for the working standard solution; and E is the mass of sample taken in grams. References 1. 2. 3. Analytical Methods Committee, rlnalyst, 1978, 103, 509. Harris, J. R., Baker, P. G., and Alliston, G., Analyst, 1977, 102, 580. Analytical Methods Committee, Analyst, 1980, 105, 161.

ISSN:0003-2654    

DOI:10.1039/AN9830801521

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

Analyst, December, 1983 1525 SHORT PAPERS Solvent Extraction and Separation from Lanthanides Miss V. V. Mudshingikar and V. M. Shinde Department of Chemistry, Shivaji University, Kolhapur 416 004, India of Thorium(lV) Keywords : Thorium( I V ) separation ; solvent extraction ; mesityl oxide; lanthanides In this paper we propose a method for the solvent extraction, separation and purification of thorium. Thorium is extracted quantitatively from a 0.1 M sodium salicylate solution of pH 3.5-5 using mesityl oxide as an extractant. The extracted metal ion is stripped with nitric acid (0.5 M) and determined photometrically with Arsenazo I11 at 665 nm. Various solvents such as tributyl phosphate,l4-rnethylpentan-2-0ne,~ mesityl oxide,3 sulph- oxides4s5 and 2-butoxyethyl ether6 have been used for the extraction studies of thorium but these methods suffer from drawbacks such as multiple extraction, heating of the aqueous phase and the use of high concentrations of salting-out agents.Bis(2-ethylhexyl) hydrogen phos- hate,^^^ dibutyl hydrogen phosphate9 and trioctylphosphine OxidelOJl have also been used for the extraction of thorium from mineral acids but they have little practical application. High relative molecular mass amines such as t r i ~ c t y l a m i n e , ~ ~ ~ ~ ~ Aliquat,14J5 Amberlite LA-1 and LA-2,16s17 tridodecylamine,ls Primene JMT1S and Alamine-33620 have also been used for the extraction of thorium(1V) but in all these methods a systematic separation study of thorium is lacking. In this paper we describe a method for the separation of thorium(1V) from lanthan- ides such as scandium, yttrium, lanthanum , cerium, praseodymium , neodymium, samarium, gadolinium and dysprosium and uranium. Experimental Reagents TCtorium(IV) solution.Prepared by dissolving 6.43 g of thorium nitrate (analytical- reagent grade) in 5 ml of 0.5 M nitric acid and diluting to 500 ml with distilled water. This was standardised21 and diluted as required. Extractant. A 50% solution of doubly distilled mesityl oxide (Fluka, b.p. 125-128 "C) dis- solved in benzene was used for extraction studies. Arsenazo III. A 0.1 yo aqueous solution was used for the spectrophotometric determination of thorium.22 General Extraction Procedure An aliquot of solution (25 ml) containing 25-100 pg of thorium(1V) and 0.4 g of sodium salicylate (0.1 M) was adjusted to pH 3.5-5 with dilute nitric acid and sodium hydroxide solu- tion and shaken for 1 min in a 100-ml separating funnel with 10 ml of 50% mesityl oxide.After separation of the two layers thorium was removed from the mesityl oxide phase by shaking with 15 ml of 0.5 M nitric acid and determined as follows: add 2 ml of Arsenazo I11 solution, adjust the pH of the solution to 1.5-2 with dilute nitric acid and sodium hydroxide solution and read the absorbance of the dark violet complex at 665 nm.22 Results and Discussion Optimum Extraction Conditions The extraction of thorium(1V) was studied at various pH values (3-9), sodium salicylate concentrations (0.025-0.15 M) and mesityl oxide concentrations ( 10-lOO~o in benzene as diluent).The extraction of thorium(1V) is effectively quantitative at pH 3.5-5.0 from 0.1 to 0.125 M sodium salicylate medium (Fig. 1) with 10 ml of 50% mesityl oxide solution. Above pH 5, the extraction decreases. The percentage extraction (E) of the metal ion was calculated1526 SHORT PAPERS Analyst, Vol. 108 Sodium salicylate concentration/M 0.025 0.05 0.075 0.10 0.125 0.150 I------ 100. c -g 90. E c 8 0 . 0 c 70 2 60 1 I I I I I I 4 5 6 7 8 9 PH Fig. 1. Extraction of thorium(1V) as a function of pH (A) and salicylate con- centration (B). by stripping the metal ion from the organic phase with a subsequent photometric determination with Arsenazo 111. The distribution ratio (D) was calculated by using the relationship V W l V O x E D = where Vw and Vo are the volumes of aqueous phase and organic phase, respectively.Of the solvents tried xylene and toluene could also be used in place of benzene. Benzene was, how- ever, preferred as it gives clear phase separation although precautions are necessary as it is carcinogenic. 100- E Nature of the Extracted Species The log - log plot of distribution ratio 'ucysus mesityl oxide concentration at fixed pH and salicylate concentration gave a slope of 1.8, indicating the presence of two solvent molecules in the extracted species. The extraction mechanism thus involves solvation of thorium salicylate salt. Period of Equilibration mesityl oxide is needed for complete extraction of thorium(1V). adverse effect on the extrattion of thorium. Variation of shaking time showed that a single extraction for 1 min with 10 ml of 50% Prolonged shaking has no Tolerance of Diverse Ions The extractions were carried out by the recommended procedure in the presence of a number of foreign ions in order to observe their interference in the extraction and subsequent spectro- TABLE I TOLERANCE OF DIVERSE IONS IN THE SEPARATION OF 100 pg OF THORIUM Ion added Tolerance limitlpg Ag(I), Fe(II), Hg(II), Pd(II), Bi(III), Au(III), Cr(III), Pt(IV), Mo(VI), Cu(II), Ni(II), Mn(II), Zn(II), Cd(II), Zr(IV), ascorbate, citrate, phosphate, sulphate .... .. .. .. .. .. 600 EDTA, tartrate .. .. .. .. .. .. .. .. None W(VI), Cr(V1) .. .. * . .. .. 2 000 Ru(III), Nb(V), V(V),'Ta(V), oxalate, thiourea, chloride,' hitrate' . . 1000December, 1983 SHORT PAPERS 1527 photometric determination of thorium.The results in Table I show that a large number of cations and anions did not interfere. Notable interferences are given by ions such as EDTA and tartrate. Separation of Thorium( IV) from Scandium( 111), Yttrium( 111), Lanthanum( 111), Cerium( IV), Praseodymium( 111), Neodymium( 111), Samarium(III), Gado- linium( 111), Dysprosium(II1) and Uranium(V1) Elements such as scandium, yttrium, lanthanum, cerium, praseodymium, samarium, gadolinium, dysprosium and uranium are only partially extracted (ca. 30%) when thorium is extracted from 0.1 M sodium salicylate solution (pH 4) with 10 ml of 50% mesityl oxide dis- solved in benzene. Large amounts of added ions remain in the aqueous phase (A). The partially extracted metal ions are selectively removed from the organic phase by back-washing with distilled water or with 0.01 M sulphuric acid (for cerium only).The back-stripped aqueous phase (B) is combined with the original aqueous phase (A) and in the combined aqueous phase metal ions are determined by standard procedures. Thorium does not strip with either water or 0.01 M sulphuric acid and remains in the organic phase. It is subsequently removed from the organic phase by back-washing with 0 . 5 ~ nitric acid and determined spectrophotometrically with Arsenazo I11 as described under General Extraction Procedure. TABLE I1 SEPARATION OF THORIUM(IV) FROM BINARY MIXTURES AND MULTI-COMPONENT SYSTEM Composition of mixturelpg Th, 100; Sc, 500 . . .. Th, 100; Y, 500 . . .. Th, 100; La, 500 . . .. Th, 100; Ce, 200 .. .. Th, 100; Pr, 500 . . .. Th, 100; Nd, 500 . . .. Th, 100; Sm, 500 . . .. Th, 100; Gd, 500 . . .. Th, 100; Dy, 500 . . .. Th, 100; U, 500 .. Th, 100; Sc, 100; Y,' 100; La, 100; Pr, 100; Nd, 100; Sm, 100; Dy, 100; U, 100; Gd, 100 . . .. .. Recovery of thorium from triplicate analysis/ pg 99.6 100.0 99.5 99.1 99.6 99.3 99.6 99.3 99.3 99.1 99.0 Relative error, yo 0.4 0.0 0.5 0.9 0.4 0.7 0.4 0.7 0.7 0.9 1 .o Recovery of added ion from triplicate analysis/ pg 100.0 99.0 100.0 99.5 99.5 99.8 99.2 100.0 100.0 100.0 Relative error, % 0.0 1.0 0.0 0.5 0.5 0.2 0.8 0.0 0.0 0.0 Spectrophotometric reagent used for added ions Arsenazo Pa Arsenazo P4 Arsenazo I*6 Arsenazo 111'6 PARz7 PARB7 Arsenazo Arsenazo P4 PAR'7 PAR'@ * Thorium is determined with Arsenazo I11 as described under General Extraction Procedure.The recovery of thorium and that of the other added ions was greater than 99.0%. Thorium(1V) was also separated from the multi-component system. The results of the separa- tion for binary mixtures as well as the multi-component system are reported in Table 11. The reproducibility of the method was satisfactory and the determination required only 20 min. Six determinations with 100 pg of thorium(1V) gave a mean absorbance value of 0.6 & 0.02 with a standard deviation of 1.4 x 10-2 and a coefficient of variation of 2.3%. The proposed method is precise and accurate. The authors thank the Council of Scientific and Industrial Research (New Delhi) for award- ing a fellowship to one of them (V.V.M.). References 1. 2. 3. 4. 5. 6.Cheng-Chyuan Chen, and Gann Ting, J . Chin. Chem. Soc. (Taipei), 1977, 24, 25. Norio, I., Talanta, 1971, 18, 21. Jen Chun-Hwa, and Cheng Chen Mei, Chemistry, Taipei, 1968, 4, 148. Markl, P., Mikrochim. Acta, 1973, 907. Reddy, A. S., and Reddy, L. K., Sep. Sci., 1977, 12, 641. Jenkins, I. L., Lidington, D. H., and Wain, A. G., J . AppZ. Cheun., 1969, 19, 213.7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 1528 SHORT PAPERS Analyst, Vol. 108 Mitsugashira, T., Yamana, H., and Suzuki, S., Nippon Kagaku Kogyo, 1977, 50, 2918. Percival, D. R., and Martin, D. B., Anal. Chem., 1974, 46, 1742. Endre, U., Laszlo, G., and Gyula, N., Magy. Kem. Foly., 1969, 75, 166. Pollock, E. N., Anal. Chim. Acta, 1977, 88, 399. Guyon, J. C., and Meddison, B., Mikrochim.Acta, 1975, I, 133. Caspito, M., and Rigali, L., Anal. Chim. Acta, 1971, 57, 109. Ejaz, M., Talanta, 1976, 23, 193. Bhandiwad, V. R., Swarup, R., and Patil, S. K., J. Radioanal. Chem., 1979, 1, 52. Contarini, M., Pasguinelli, P., and Rigali, L., Anal. Chim. Ada, 1979, 89, 397. Sawant, M. A., and Khopkar, S. M., Talanta, 1980, 27, 451. Tsuneo, S., Bunseki Kagaku, 1968, 17, 1187. Veselsky, J. C., J. Radioanal. Chem., 1978, 46, 247. Hiroto, W., Nippon Kagaku Kogyo, 1970, 43, 100. Florence, T. M., and Farrar, Y . J., Aust. J. Chem., 1969, 22, 473. Vogel, A. I., “A Text Book of Quantitative Inorganic Analysis,” Longmans, London, Third Edition, Hiroshi, O., and Keiichi, S., Bunseki Kagaku, 1970, 19, 547. Tsuneo, S., Anal. Chim. Acta, 1967, 37, 75. Pande, S. P., and Munshi, K. N., Curr. Sci., 1972, 41, 330. Shibata, S., Takeuchi, E., and Matsumae, T., Anal. Chim. Acta, 1959, 21, 177. Spitsyn, P. K., and Shvarev, V. S., Zh. Anal. Khim., 1970, 25, 1503. Munshi, K. N., and Dey, A. K., Anal. Chem., 1964, 36, 2003. Okamoto, K., and Takehiko, T., Bunseki Kagaku, 1971, 20, 870. Busev, A. I., and Ivanov, V. M., Vestn. Mosk. Univ. Khim., 1960, 3, 52. 1960, p. 442. Received May l l t h , 1983 Accepted July 19th, 1983

ISSN:0003-2654    

DOI:10.1039/AN9830801525

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

1528 SHORT PAPERS Analyst, Vol. 108 Procedures for the Measurement of pH in Low Ionic Strength Solutions Including Freshwater Arthur K. Covington and Peter D. Whalley Electrochemistry Research Laboratories, Department of Physical Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU and William Davison Freshwater Biological Association, Windermere Laboratory, The Ferry House, Ambleside, Cumbria, LA22 OLP Keywords : PH measurement; flow cell; liquid junction ; freshwater The most commonly measured chemical parameter in natural waters is the pH value. Its importance is emphasised by the extensive use of pH in geochemical investigations. Such studies constitute some of the few situations where pH is required to have a more fundamental meaning in terms of the hydrogen ion activity or concentration.The interpretation of pH, in terms of the hydrogen ion activity, is ultimately limited by the conventional nature of the single ion activity. However, practically, the variation of the liquid-junction potential poses the major uncertainty. The theoretical difficulties surrounding the concepts of the single ion activity and the liquid-junction potential have been well dis- cussed.1*2 Before these points can be considered, there is a requirement for practical and reproducible liquid-junction formation. The potential difference generated across a liquid - liquid interface is known to be influenced by the geometry of the junction, that is, by its structure and the means of confining the salt- bridge solution against the density gradient.3 Also, any dilution or contamination of the salt- bridge solution by the calibration or test solution will have a detrimental effect on the repeat- ability and reproducibility4 of the over-all cell potential difference.With the exception of sleeve-junction electrodes, commercially available reference electrodes have no facilities for readily renewing the junction and hence removing contaminants or diluents from the vicinity of the liquid junction. These problems have been recently re- emphasised by Illingw~rth.~ Sleeve junctions, unfortunately, suffer from a comparativelyDecember, 1983 SHORT PAPERS 1529 high and non-uniform leakage rate of the bridge solution, which may be unacceptable in small volumes of very dilute samples. As an alternative to existing constrained liquid junctions currently available, which are believed to have several major disadvantages,6 we suggest the adoption of a renewable, free- diffusion liquid junction suitable for precise measurements in very dilute solutions including freshwater.Owing to the obvious uncertainty in the "true" pH of a freshwater sample, dilute buffer solutions of known pH were used to establish the reproducibility of the pro- posed pH assembly. The pH assembly used in this work is based on one previously described by Culberson' for marine use. A similar cell has also been successfully used in this laboratory for estuarine pH measurements.8 Experimental Assignment of P(u,) [or pH(S)] Values to Dilute Buffer Solutions Materials and eqMipment Analytical-reagent grade reagents (BDH Chemicals) were used throughout and dried, where appropriate, at 120 "C.Platinum and silver - silver chloride electrodes were prepared as described by Bates.g Potential differences were recorded using a Hewlett-Packard 34558 digital voltmeter. A well lagged water-bath maintained to k0.01 "C was used. Method assigned using cells without liquid junctions as follows : The p(aH) values of four dilute buffer solutions (ionic strength FS 0.01 mol kg-1) were Pt I H, I buffer + C1- I AgCl I Ag where the cell e.m.f. ( E ) is related to the acidity function p(aHyg) by Values of p(aHyc,) were obtained at five chloride concentrations (between and mol k g l ) , permitting a value of p(aHyCl)" to be obtained by extrapolation to zero chloride concentration.This allowed the p(a,) value to be evaluated with the aid of the Bates- Guggenheim conventionlo for the single ion activity coefficient : The constituents and values of p(aH) of the four dilute buffer solutions between 5 and 30 "C are given in Table I. Although expressed to three decimal places, the very l ~ w buffer capacity of these solutions means that, for calibration purposes, only two figures after the decimal point should be considered significant. TABLE I VALUES OF p(a,) FOR DILUTE BUFFER SOLUTIONS BETWEEN 5 AND 30 "C TernperaturelOC Molalityl I A \ Buffer solution mol kg-l 5 10 15 20 25 30 KHC,H,O, .. . . 0.01 4.114 4.111 4.111 4.112 4.117 4.124 Na,HPO,. KH,PO,'(i + i)' . . 0.0025 7.148 7.123 7.101 7.082 7.068 7.067 0.002 5 . _ _ ~ - KH,PO, - Na,HPO, (1 + 3.5) .. 0.0008695 7.684 7.607 7.641 7.621 7.605 7.593 N%B,O,.lOH,O . . .. . . 0.005 9.401 9.340 9.284 9.237 9.195 9.130 0.003 0431630 SHORT PAPERS Analyst, Vol. 108 Operation of the Flow Cell The flow cell is shown in Fig. 1 and, following a suggestion by Culber~on,~ was mounted in a Perspex box, which gave rigidity and acted as a water-jacket. The glass micro electrode (Russell pH Ltd., Auchtermuchty, Scotland) was fitted with a glass sleeve andmatched with a corresponding socket. A sharp T-junction was found to be critical to the formation of a reproducible liquid junction and to the fast response of the cell. This had been achieved by forming a pinhole in a glass capillary tube using a tungsten wire and sealing a second capillary tube around the hole to form the T-junction.Fig. 1. Modified flow cell.' (A) Potassium chloride reser- voir; (B) reference electrode; (C) glass electrode; (D) T- junction. In the previous use of this type of pH assembly by Culberson7 and Butler et aZ.,8 samples from syringes were injected into the flow cell and hence measurements were made on static solution. For solutions of very low ionic strength and buffer capacity, a flowing solution was necessary, thus preventing the accumulation of dissolution products from the glass electrode and sur- rounding cell remaining in the vicinity of the pH sensing rnembrane.l1-ls The use of a flowing solution had the further advantage that the liquid junction could be within 1 cm of the glass electrode, thereby greatly reducing the over-all d.c.resistance of the cell without the risk of the potassium chloride solution from the salt bridge contaminating the sample. A fresh liquid junction is simply formed by releasing potassium chloride solution from the reservoir illustrated in Fig. 1. The liquid junction was clearly visible as a sharp boundary a few millimetres below the T-junction, thus maintaining the essential requirement of cylindrical symmetry for this type of juncti0n.1~ Although the formation of a fresh liquid junction was not always necessary for solutions of similar composition, it was standard practice to reform the liquid junction for each solution, as this process generally disturbed the cell potential difference by a maximum of only 1-2 mV for less than 20 s. The simplest, and by far the most effective, method for obtaining a stable flow was by using a syphoning action directly from the sample bottle.This method was compatible with the requirement that this pH assembly be suitable for field use. For the flow cells used in this work, no flow dependence of the cell potential difference for any of the solutions was observed in the flow-rate range 1 4 cm3 min-1. At lower flow-rates, drifting results were obtained that were attributable to poor solution flushing at the glass electrode. Results and Discussion To demonstrate the suitability of the proposed flow cell for obtaining high calibre pH data of the quality required for geochemical investigations, the pH values of the dilute buffer solutions listed in Table I were determined using the flow cell.The slope of the electrode pair was first determined using NBS 1 + 1 and 1 + 3.5 phosphate and disodium tetraborate(II1) buffer solutions. Typical results, obtained at room temperature (ca. 23 "C), are shown in Table 11. This shows that excellent agreement is possible between derived pH values and those obtained from cells without liquid junctions.December, 1983 SHORT PAPERS 1531 TABLE I1 VALUES OF pH FOR DILUTE BUFFER SOLUTIONS OBTAINED USING THE FLOW CELL CALIBRATED ON THE NBS BUFFER SCALE AT 23 “C Cell calibrated using 1 + 1 and 1 + 3.5 phosphate and disodium tetraborate(II1) buffer solutions. Buffer solution* pH (NBS) P(‘H) KHC8H,0, . . 4.124 4.115 Na,HPO, - KH,PO,( 1 + ‘1) . . 7.077 7.073 KH,PO, - Na,HPO, (1 + 3.5) . . 7.610 7.611 Na,B,O,. 10H,O .. . . . . 9.210 9.212 * Concentrations as in Table I. As an example of the effect of the liquid junction in practical reference half cells on the observed pH, a comparison was made between the flow cell, a combination electrode (Radio- meter Type GK2401c) and glass/saturated calomel electrode with a ceramic plug liquid junc- tion (Russell pH Ltd., Type CRR). Identical calibration procedures were adopted for all systems. At the level of discrimination required (& 0.01 pH) no dependence on the calibra- tion scale, either BS or NBS, would be apparent.2 Freshwater samples were obtained from Lake Windermere and measurements were made within 30 min at the iut situ temperature (7 “C). Measurements on dip electrodes were conducted in enclosed, full beakers (to minimise gaseous exchange) and at a constant but unspecified stirring rate. The pH data presented are often based on single measurements at a given instant. It is the purpose of the given results to highlight the differences that can arise between electrodes.In this situation the use of statistics would be misleading. TABLE I11 INTERCOMPARISON OF pH VALUES OBTAINED FROM THREE ELECTRODE SYSTEMS AT 7 “c pH value , Sample* Flow cell Na,HPO, - KH,PO, (1 + 1) . . 7.13 Na,HPO, - KH,PO, (1 + 3.5) . . 7.65 7.22 7.15 7.18 7.09 7.32 Freshwater samples. . . . . . 7.21 * Buffer concentrations as in Table I. Radiometer combination electrode 7.00 7.53 7.00 7.05 7.01 7.01 6.97 7.09 Russell glass/ reference pair 7.06 7.53 7.05 7.14 7.06 7.14 7.08 7.17 Table I11 shows examples of the results obtained for the three-electrode systems.The large variations between the different systems emphasises the difficulty of obtaining reproducible results using existing commercial electrodes utilising restrained liquid junctions. Although the dilute buffer solutions given in Table I can be used for ealibrating electrode pairs, they are of more use for establishing the reproducibility of the electrodes in dilute solution when cali- brated on either the BS or NBS buffer scale. The advantages of the flow cell, over existing dip-type electrodes with “restrained” liquid junctions, as a pH measuring assembly suitable for dilute, poorly buffered solutions are sum- marised as follows : the high repeatability and, more importantly, the high reproducibility offered by the use of a renewable free-diffusion liquid junction; the denser salt bridge solution is overlaid by the less dense test solution, eliminating convective flow and enhancing the forma- tion of a stable liquid junction; minimum exposure of the sample to the atmosphere, which is of great importance in poorly buffered solutions with their pH dependence on the partial pressure of carbon dioxide; the use of a slow flowing sample ensures that fresh solution is always1532 SHORT PAPERS Analyst, Vol.108 presented to the glass electrode; the avoidance of stirring effects, which is common with con- ventional dip electrodes in dilute solution15; and the high impedance electrode circuit is not broken between samples-doing so can “disturb accurate measurements for several minutes.”l6 1. 2. 3. 4. 5. 6. 7 . 8. 9. 10. 11. 12. 13. 14. 15. 16. References Bates, R. G., Crit. Rev. Anal. Chem., 1981, 10, 247. Covington, A. K., Anal. Chim. Acta, 1981, 127, 1. Perley, G. A., Trans. Electrochem. Soc., 1947, 92, 497. “Terms used in Metrology,’’ British Standard 5233 : 1978. Illingworth, J. A., Biochem. J . , 1981, 195, 259. Covington, A. K., Davison, W., and Whalley, P. D., Pure Appl. Chem., in the press. Culberson, C., in Whitfield, M., and Jagner, D., Editors, “Marine Electrochemistry,” John Wiley, Butler, R. A., Covington. A. K., and Whitfield, M., in preparation. Bates, R. G., Editor, “Determination of pH,” Second Edition, John Wiley, New York, 1973. Bates, R. G., and Guggenheim, E. A., Pure Appl. Chem., 1960, 1, 163. Ellis, S. B., and Kiehl, S. J., J . Am. Chem. Soc., 1935, 57, 2139. Perley, G. A., Anal. Chem., 1949, 21, 559. Midgley, D., and Torrance, K., Analyst, 1979, 104, 63. Guggenheim, E. A., J . Am. Chem. SOG., 1930, 52, 1315. Brezinski, D. P., Analyst, 1983, 108, 425. Johannson, G., Karlberg, B., and Wikby, A., Talanta, 1975, 22, 953. New York, 1981. Received July 4th, 1983 Accepted July 19th, 1983

ISSN:0003-2654    

DOI:10.1039/AN9830801528

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年代:1983

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1532 SHORT PAPERS Analyst, Vol. 108 Isolatian of Bergapten and Limettin from Bergamot Oil Vincent B. Croud, John R. Michaelis and Arnold G. Pindar Labovatory of the Government Chemist, Cornwall House, Stamford Street, London, SE1 9NQ Keywords ; Bergapten ; limettin ; lactonic fraction ; thin-layer chromatography ; bergamot oil Suntan products and some perfumes may contain citrus oils in order to promote tanning or enhance fragrance. These oils contain coumarins, which may have a phototoxic effect. Probably the best known of these is 4-methoxyfuro[3,2-g]chromen-7-one (bergapten) (I), also commonly known as 5-methoxypsoralen (&MOP), which is present at a level of 0.37% in bergamot oi1.l Marzulli and Maibachl in a detailed study of the phototoxicity of bergamot oil concluded that Berlock dermatitis, a condition similar to acute sunburn, can be caused by the application of products containing bergapten and exposure to sunlight. The phototoxic effects of other furocoumarin components are less certain. However, the isolation of 5,7- dimethoxycoumarin (limettin) (11) , to which bergapten may be converted, has been included in this study.This laboratory was asked to examine a number of suntan products and a perfume sample for the presence of bergapten and limettin. The determination was to be carried out by thin- layer (TLC) and high-performance liquid chromatography (HPLC) for which standard samples were required for comparison purposes. No such materials were directly available at that time and therefore it was decided to extract and purify the materials from readily available bergamot oil.A literature search yielded many methods for the determination of coumarins and psoralens in citrus oils, of which four pieces of work were particularly r e l e ~ a n t . ~ - ~ The procedures described can be separated into two distinct stages: (i) the isolation of the lactonic species from the oil; (ii) the extraction of the pure material from this fraction. Crown Copyright.December, 1983 SHORT PAPERS 1533 Considering stage (i), Suzuki et aL2 suggested an initial clean-up by eluting the sample through a Florisil column with ethyl acetate, followed by a second stage with a Florisil column and eluting with methylene chloride. The main problem in stage (ii) was the separation of bergapten from limettin.The final yield was poor and the method was, therefore, rejected. I CH3 II Sethna and Shah3 proposed a more rigorous treatment, which in fact Suzuki et aL2 had applied to some samples. This involved base hydrolysis with methanolic potassium hydroxide in order to open the lactone ring and produce hydrophilic compounds. After removal of the other components of the oil by ether extraction, the lactone ring is closed by warming with 10% sulphuric acid and the bergapten is extracted with chloroform. Both Wisneski4 and Cieri5 suggested the removal of any volatile fractions from the oil as an initial clean-up procedure, prior to isolating the lactonic fraction. The former used a vacuum distillation, the latter a steam distillation. Wisneski followed the vacuum distillation with the procedure of Sethna and Shah3 to isolate the lactonic fraction.Ether was then added to this fraction, it was cooled and crystals of bergapten and limettin were obtained that were then recrystallised four times from hot methanol. However, the authors found that the bergapten and limettin were still contaminated by other materials. It was found that elution from a silica gel 60 column with hexane - ethyl acetate (75 + 25 V / V ) led to the isola- tion of several fractions that contained solely bergapten and limettin. The first few fractions contained neither bergapten nor limettin, and these were followed by four fractions in which limettin only was found. Finally about ten fractions containing both bergapten and limettin were eluted. In this work the following isolation procedure was employed: (i) removal of the volatile fraction by vacuum distillation (this was preferred to the steam distillation as it was found easier to control and was less likely to decompose the sample); (ii) isolation of the lactonic species using the procedure of Sethna and Shah; and the separation of bergapten and limettin by TLC.During the course of the work it was noted that bergapten slowly decomposed to limettin in the presence of light, so wherever possible the apparatus was protected from light. Some bergapten was obtained from an alternative source; this was used to confirm the identity of the product obtained from this procedure. This bergapten was also found to contain a trace of limettin. Other possible procedures to clean up the lactonic fraction were sought.Procedure Take bergamot oil (50 ml or 45 g) and distil up to 60 "C under vacuum (1-2 mmHg) (1.3- 2.6 mbar). Stir and reflux the residue for 3 h with a mixture of potassium hydroxide (10 g) in methanol (67 ml) and water (33 ml). Cool and add saturated sodium chloride solution (100 ml), transfer into a separating funnel, wash with ether (2 x 50 ml) and discard the ether washings. Neutralise the solution with sulphuric acid (10% V/V) and add a further portion of acid (30 ml). Heat on a water-bath for 1 h. Extract with chloroform (3 x 50 ml) and wash successively with 1% (m/V) sodium hydrogen carbonate solution (2 x 25 ml) and water (25 ml). Dry the chloroform extract with anhydrous sodium sulphate and filter. Add xylene (10 ml) and remove the chloroform on a rotary evaporator.1534 SHORT PAPERS Analyst, V d .108 Condition a silica gel 60 column (150 mm x 15 mm i.d.) with hexane - ethyl acetate (75 + 25 V/V). Add the residual xylene solution from the rotary evaporator to the column and elute with the same mobile phase that was used to condition the column. Collect 10-ml fractions. Check each for the required substances by TLC on silica gel 60 using hexane - ethyl acetate (75 + 25 V / V ) as the mobile phase. (Bergapten gives a strong green fluorescence at an R, of 0.20 when irradiated at 366nm and limettin shows a strong blue fluorescence at an R, of 0.23.) Combine the fractions containing bergapten or limettin, evaporate to dryness in a rotary evaporator and redissolve in acetone (5 ml).Apply an aliquot (100 pl) of this solution to a silica gel 60 TLC plate (200 mm x 200 mm, silica 0.25 mm thick) as a band of 180 mm in length. Remove the band of the required material (bergapten or limettin) from the plate and wash with acetone. Filter and remove the acetone in a rotary evaporator to yield either bergapten or limettin. Elute the plate four times with hexane - ethyl acetate (75 + 25 V / V ) . Results and Discussion Both bergapten and limettin were recovered at a level of 3 mg per plate. The literature1 gives the concentration of bergapten in bergamot oil as 0.37%, therefore 92% of the bergapten was recovered. As bergamot oil is a natural product the concentration of bergapten may vary depending on the source of the oil, so 92% is purely a guide to the efficiency of the procedure.TABLE I ANALYSIS OF THE PURITY OF LIMETTIN AND BERGAPTEN BY ULTRAVIOLET SPECTROSCOPY AND MASS SPECTROMETRY Mass spectrometry I Ultraviolet spectroscopy A , \I Amax. (limettin)/ Amax. (bergapten)/ ' nm nm mlz 219 219 206 241* 248 178 321 257 163 266 149 312 135 85 * Shoulder on peak. Limettin A 7 Relative Molecular intensity ion 100 C11H1004 82.7 C,,H,,O, 48.1 C,H,O, 16.4 25.0 18.3 I 1mlz 216 201 188 173 145 89 1 Bergapten v --A- Relative Molecular intensity ion 100 C12H804 30.9 C11H504 12.1 C,,H8O, 66.2 C,,H,O, 30.4 C,H50, 23.2 C,H5 The purity of these compounds was checked by both ultraviolet spectroscopy and mass spectrometry and the results are presented in Table I. The mass spectrometric results showed that limettin was absent from the bergapten and vice veysa. The solution of bergapten and limettin in acetone obtained from the silica column was retained for six weeks in order to obtain further supplies of the purified materials. In this period the recovery of bergapten decreased to about 2 mg per plate; however, this was still an adequate amount for use as a standard. The solution was stored in a darkened bottle in a refrigerator in order to slow down this decomposition. This work forms part of a larger programme of work undertaken by the Laboratory of the Government Chemist on behalf of the Department of Trade. References 1. 2. 3. 4. 5. Marzulli, F. N., and Maibach, M. D., J. SOC. Cosvnet. Chem., 1970, 21, 695. Suzuki, H., Wakamura, K., and Iwaida, M., J. SOG. Cosmet. Chem., 1979, 30, 393. Sethna, S. M., and Shah, M. N., Chem. Rev., 1945, 36, 1. Wisneski, H., J . Assoc. Off. Anal. Chem., 1976, 59, 547. Cieri, U. R., J. Assoc. 08. Anal. Chem., 1969, 52, 719. ' Received May 26th, 1983 Accepted July 28th, 1983

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DOI:10.1039/AN9830801532

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年代:1983

数据来源: RSC

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December, 1983 SHORT PAPERS Simultaneous Determination of Fentiazac and 1535 p-Hydroxyfentiazac in Plasma by High-performance Liquid Chromatography with Ultraviolet Detection Pauline S. Dowell* Wyeth Laboratories, Huntercombe Lane South, Taplow, Maidenhead, Berkshire, SL6 OPH Keywords : Fentiazac determination ; p-hydroxyfentiazac determination ; high- performance liquid chromatografihy ; ultraviolet detection Fentiazac, [4-(4-chlorophenyl)-2-phenylthiazol-5-yl]acetic acid (I), has been shown to be an effective and well tolerated non-steroidal anti-inflammatory agent in man.l Gas-chromato- graphic methods have previously been reported for assay of fentiazac in plasma2s3; however, there have been no previous published reports of the quantitation in human plasma of p- hydroxyfentiazac (11), known to be a major metabolite of the drug in animal^.^ A method has been developed for the simultaneous determination of fentiazac and 9-hydroxyfentiazac in plasma.The method described uses high-performance liquid chromatography (HPLC) with ultra- violet detection and has a lower detection limit of 20 ng ml-l for fentiazac and of 50 ng ml-l for p-hydroxyfen tiazac. NYS I OH II Experimental Equipment The HPLC system consisted of a double reciprocating pump (Model 750/03, Applied Chromatography Systems, Luton, Bedfordshire), an automatic injection system (WISP, Model 710A, Waters Associates, Northwich, Cheshire) and an LC/UV detector (Pye Unicam, Cambridge). Quantitation was carried out on a computing integrator operating in the peak- height measurement mode (SP4100, Spectra Physics, St.Albans, Hertfordshire) . Glassware All glassware was silanised by soaking in 2% dimethylchlorosilane in ethyl acetate for 30 min. The glassware was then dried, washed with distilled water, dried, soaked in methanol for 30 min and finally dried. Reagents Methanol and dichloromethane, HPLC grade, were obtained from Rathburn Chemicals, Walkerburn, Peeblesshire. Formic acid was supplied by BDH Chemicals Ltd., Poole, Dorset. The internal standard, [2,4-di-(@-methoxyphenyl) thiazol-5-yl]acetic acid, was synthesised in the Chemistry Department of Wyeth Laboratories. * Present address : Glaxo Group Research Ltd., Greenford Road, Greenford, Middlesex.1536 SHORT PAPERS Analyst, Vol. 108 Solvent Extraction Procedure Internal standard (250 ng in 25 p1 of methanol) was added.The plasma was adjusted to pH 2 with 25 pl of 5 N hydrochloric acid, and the mixture extracted with dichloromethane (3.5 ml) by vortexing for 1 min. Following centrifugation at 1500 rev min-l for 10 min, the upper aqueous phases were discarded and the lower organic phases were transferred into 5-ml flat-bottomed glass tubes. The extracts were evaporated to dryness at 45 "C under a gentle stream of oxygen-free nitrogen. Residues were reconstituted in 150 pl of methanol - 1% V/V formic acid solution (77 + 23) before being chromatographed. Aliquots of plasma (500 pl) were dispensed into silanised glass test-tubes. Chromatography The extracts (120 pl) were injected on to a pBondapak C18 reversed-phase analytical HPLC column (supplied by hplc Technology Ltd., Macclesfield, Cheshire), 0.5 cm i.d.and 25 cm long. This column was used in conjunction with a pre-column of the same material, 0.5 cm i.d. and 5 cm long (available from hplc Technology). The column was eluted with methanol - 1% V/V formic acid solution (77 + 23) at a flow-rate of 2.0 ml min-l. The pressure was approximately 1 700 p.s.i. Fentiazac, $-hydroxyfentiazac and the internal standard were detected by means of their absorbance at 310 nm. Results and Discussion A typical chromatogram is shown in Fig. 1. The lower limit of detection is 20 ng ml-l for Calibration graphs were linear over the ranges fentiazac and 50 ng ml-l for the metabolite. i Time/min + Fig. 1. Typical chro- matogram obtained from plasma containing 400 ng of fentiazac and p - hydroxyfentiazac, pro- cessed as described.Retention times: A ( p - hydroxyfentiazac), 5.1 : B (internal standard), 6.0; C (fentiazac), 7.7 min.December, 1983 SHORT PAPERS 1537 20-1 000 ng ml-l (fentiazac) and 50-1 000 ng ml-l (P-hydroxyfentiazac). The reproducibility of the method was investigated by analysing ten replicate samples of plasma at different concentrations. The resulting coefficients of variation of peak-height ratios for fentiazac were 10.7, 7.0 and 2.3% at 20, 50 and 1000 ng ml-l and for P-hydroxyfentiazac were 9.0 and 1.7% at 50 and 1000 ng ml-l, respectively. The method would appear to be specific for fentiazac and its +-hydroxylated metabolite. In a recent study by Mr. S. Rhenius of Life Science Research (personal communication), in which l4C-labelled fentiazac was administered orally t o volunteers, the only dry derived material detected in plasma by TLC was the unchanged drug and its 9-hydroxylated metabolite and their conjugates (glucuronide/sulphate) .As the conjugates would not be extracted from plasma, it is therefore unlikely that any other metabolite of fentiazac present in the plasma could interfere with the assay. The method described here is a rapid, sensitive and specific method for the determination of fentiazac and P-hydroxyfentiazac and has been used successfully to monitor concentrations of the drug and its metabolite in plasma from subjects administered oral doses of 200 mg of the drug. A typical plasma concentration - time graph obtained using this method of analysis is shown in Fig.2. Concentrations of P-hydroxyfentiazac after a single dose of fentiazac were of a comparable order of magnitude to those of the unchanged drug, maximum concentrations being about 40% of those of fentiazac. I 1 I I I I 0 2 4 6 8 10 12 Time after dosing/h Fig. 2. Typical plasma concentration versus time graph obtained after administration of a single 200-mg oral dose of fentiazac to a male volunteer. A, p - Hydroxyfentiazac ; B, fentiazac. Fluorescence detection, using an excitation wavelength of 313 nm and an emission wave- length of 390 nm, has been briefly examined and has been found to be a good alternative to ultraviolet absorbance as a means of detection. It is as sensitive as ultraviolet detection, but the limit of detection has not been investigated. Therefore, it is not known whether this method offers any advantages in sensitivity. The author thanks Dr. H. M. Norbury and Miss L. M. Whitfield for technical assistance and Dr. D. M. Pierce for helpful discussions. References 1. 2. 3. 4. Marmo, E., Curr. Med. Res. Opin., 1979, 6, 53. Quattrini, M., Zanolo, G., Mondino, A., Giachetti, C., and Silvestri, S., Arzneim. Forsch., 1981, 31, Zanolo, G., Giachetti, C., Mondino, A., Silvestri, S., Bianchi, E., Segre, G., and Gomarasca, P., Fumero, S., Mondino, A., Silvestri, S., Zanolo, G., De Marchi, G., and Pedrazzini, S., Arzneim. 1046. Avzneim. Forsch., 1981, 31, 1098. Forsch., 1980, 30, 1253. Received May 23rd, 1983 Accepted July 29th, 1983

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DOI:10.1039/AN9830801535

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年代:1983

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1538 Analyst, December, 1983 Book Reviews TUNNELLING SPECTROSCOPY : CAPABILITIES, APPLICATIONS AND NEW TECHNIQUES. Edited by P. K. HANSMA. Pp. xviii + 493. Plenum. 1982. Price $65. ISBN 0 306 41070 2. Although the technique of inelastic electron tunnelling spectroscopy (IETS) was discovered in 1966, a glance at the dates of the many references in this volume shows that virtually all the published work has appeared within the last 8 years. Certainly its impact on surface science has been relatively recent, and this reviewer would regard it as a new technique. Whenever a new technique or a new field of research is opened up, a learned volume soon appears that purports to bring together all known aspects of the subject. Often the volume is rapidly overtaken by events and sinks from sight after a short life, but if the new field is fortunate the text is of much quality that it is recognised at once as definitive.IETS is so fortunate and Hansma’s book is such a volume. Firstly, it is comprehensive. The subject matter goes all the way from a very basic introduction, through chapters that provide valuable experimental experience and know-how, through descriptions of the underlying physics, to the many, often surprising, ways in which IETS has been applied. For the complete beginner the very first chapter, by the Editor himself, is almost worth the entrance money alone. Secondly, it is exceptionally well illustrated. The diagrams have obviously been chosen carefully, for they are both clear and copious enough to illustrate nearly every point made in the text.Thirdly, it is easy to read. With 16 chapters divided between 22 authors, uniformity of style, let alone of readability, might be considered impossible to achieve, but in fact one is not particularly aware of having to make adjustments on going from one chapter to another, nor have any difficulties in comprehension been found. In addition, the heading - sub-heading format chosen ensures that the text is sub-divided at reasonable intervals; there is nothing more daunting than having to plough through a text in which the sections seem endless and the paragraphs interminable. Fourthly, as far as this beginner can tell, it contains most, if indeed not all, the references to published work in IETS. Lastly, and most importantly, it has an authoritative ring about it that is impossible to define but easy to recognise, that sets it aside as .. . definitive. As a major restriction on the application of IETS at present is that only a very few barrier (z.e., insulating) materials have been found to be suitable, it is remarkable that such a range of applica- tions has appeared in the literature. The reason is simple, and is given by the Editor in the first chapter, viz., “Fortunately . . . the two best tunnelling barriers, aluminium oxide and magnesium oxide, are of interest . . . as catalysts and catalyst supports.” From that fortunate coincidence has stemmed the large volume of experimental measurements, nearly all performed with the intention of modelling real catalytic systems, from all of which examples may be found in the book.This reviewer has no hesitation, therefore, in recommending the book to all those groups of workers interested in surface properties and techniques, and especially to those involved in basic catalytic research. The description “definitive” is applied for several reasons. As a definitive volume its price of CU. L40 is not excessive. J. C. RIVIJ~RE L’ANALYSE BIOCHEMIQUE QUANTITATIVE PAR NANOCHROMATOGRAPHIE EN COUCHE MINCE. By MICHEL BOUNIAS. Pp. vi + 198. Masson. 1983. Price F160. ISBN 2 225 78914 2. A subtitle of the book indicates that it is restricted to techniques using prepared plates, on flexible supports, and the book deals only with TLC plates prepared on supports which are both flexible and translucent. Thus the uses of TLC plates prepared on glass or aluminium are not included in the discussions.The author has made a sensible division of the work; the first part deals with the general methodology and it is without doubt an excellent, if brief, review of the techniques of plate preparation, spotting, development, visualisation and quantisation of spots. The reader is left in no doubt that the author is well versed in quantitative TLC. The second part-the major portion of the book-is devoted to particular applications that cover those substances encountered in biochemistry and most commonly analysed by this technique. Thus, amino acids, hormones, lipids, proteins, sugars, vitamins and inorganic ions are discussed.BOOK REVIEWS 1539 Each section is well documented with values of RF obtained in various systems.are up-to-date and are generally well chosen. etc. presented and will certainly be of use to analytical biochemists concerned with TLC. The references The third section, approximately 20 pages, deals with new techniques, radiochroma tography, However, overall the volume is well It is a somewhat brief and less pleasing section. I,. S. BARK NEW TOXICOLOGY FOR OLD. A CRITIQUE OF ACCEPTED REQUIREMENTS AND METHODOLOGY. PROCEEDINGS OF THE EUROPEAN SOCIETY OF TOXICOLOGY MEETING HELD IN DUBLIN, AUGUST 17-19, 1981. Edited by P. L. CHAMBERS and C. M. CHAMBERS. Archives of ToxicoZogy, Supplement 5. Pp. x + 394. Springer-Verlag. 1982. Price DM94; $41.80. ISBN 3 540 11406 8. I believe that it is important to say at the outset that there is almost no analytical information contained in this book.As the title indicates, the book consists of a collection of papers presented at the 1981 meeting of the European Society of Toxicology. The theme of this meeting was “New Toxicology for Old” and the book contains 72 separate papers which attempt to address this subject. The book has been divided into five separate topic areas, e.g., “Critical Evaluation of Protocols used in Routine Toxicity Studies,’] with a series of free communications collected together at the end. The papers are usually only a few pages long and I found them relatively easy to read even when the subject tackled was one with which I was totally unfamiliar. The range of disciplines represented was wide and there are certain areas of the book in which I find it difficult to comment on the quality of the science or to challenge the validity of the views put forward by the authors.However, even in this latter category I found several papers that were both interesting and provocative. I personally found the first section of the book the most useful. This challenged some of the traditional approaches to routine toxicology and I particularly support the view of the authors who argued in favour of flexible guidelines for regulatory toxicology. I also appreciated the paper by Smeets, which explained the complexities of the EEC Sixth Amendment on the Hazard Assess- ment of New Chemicals in a refreshingly simple manner. Other sections of the book cover such diverse subjects as neurotoxicity, non-invasive and invasive techniques, drugs in obstetrics and gynaecology, statistics in toxicology and the histo- pathology of toxic agents.The papers presented indicate that the meeting at least went some way towards its objective of putting forward new approaches to toxicology and was certainly critical of some of the existing protocols. For readers like myself who did not have the opportunity to attend this important symposium, I feel that this volume provides a useful means of obtaining a flavour of the papers presented. G. T. STEEL ENRICHMENT TECHNIQUES FOR INORGANIC TRACE ANALYSIS. CHEMICAL LABORATORY PRACTICE. By ATSUSHI MIZUIKE. Pp. vii + 144. Springer-Verlag. 1983. Price DM72; $29.80. ISBN 3 540 12051 3. Inorganic trace analysis is a field that has seen rapid development in recent years, especially with respect to instrumentation. The introduction of this book a t this time is fortunate, as many chemists now find that their limitations are essentially chemical and no longer instrumental. It should be obvious from the scope of the title and the shortness of the text (109 pages plus references and appendices) that in-depth discussion of any one technique is necessarily restricted.Indeed, some techniques such as zone melting are dispensed with in one page or less. The first three chapters discuss the need for enrichment techniques in trace element analysis and some of the unique problems associated with trace analysis. The discussion on contamination control is especially good and complete considering its length (12 pages). Succeeding chapters cover specific methods of analyte enrichment such as volatilisation, selective dissolution, precipita- tion, electrochemical dissolution and deposition, sorption, ion exchange, liquid chromatography, flotation, freezing and zone melting.The last two chapters deal with specialised enrichment techniques for water and gas analysis. Three appendices list the physical properties of solvents, masking agents for cations and ion- exchange data. The references are reasonably complete (785), up to date and pertinent. The only serious criticism seems to be the brevity of treatment of many subjects, yet the author’s1540 BOOK REVIEWS Analyst, Vol. 108 stated intent seems to have been met. The text may be especially valuable as a university text or reference handbook for the inexperienced analyst.The book is well written in good English, and has a clean text and clear graphics. Even the most experienced analyst should re-discover some concentration techniques that may be useful. Altogether, the book is an excellent summary of available techniques though it falls short of being the comprehensive monograph that is needed. J. R. MOODY VIBRATIONAL INTENSITIES IN INFRARED AND RAMAN SPECTROSCOPY. Edited by WILLIS B. PERSON and G. ZERBI. Pp. xvi + 466. Elsevier. 1982. Price $104.75; Dfl225. ISBN 0 444 42115 7 (Volume 20); ISBN 0 444 41699 4 (Series). This book is neither a totally balanced description of its subject matter nor merely the 20 papers presented a t a summer school held a t Belgirate, on the bank of Lake Maggiore, in August 1977, with some subsequent updating.An attempt has been made to cover the subject area in a coherent form with cross-referencing, but success would have been greater with stronger editing of symbols and related details. For instance, there is an important equation for the measured intensity expressed as a molar cross-section, ri for the ith absorption band, which can be written Studies in Physical and Theoretical Chemistry, Volume 20. Versions are given in equations 3.72, 6.2, 7.1 and 8.2; two of these versions use the calculus associated with c.g.s. units and two with SI, although these latter differ as one introduces free space properties via the permittivity,co, and the other via the permeability, po. They differ in the symbols for degeneracy, g i above, for the Avogadro constant, L, the dipole vector, ;, and the wavenumber of the band centre, Gi, while Qi for a normal co-ordinate is used consistently.All this is confusing for the student and gives the subject an unwarranted air of mystique. The main scientific theme is understanding and predicting infrared and Raman intensities. There are a few side issues, such as planetary atmospheres, but these seem included merely because they were given at the same summer school. Four interlocking themes appear which together dominate the important chapters. (a) Solving “the sign problem.” Referring to the,equation above it is clear that a measurement of ri leads directly to I @/aQi 1; the sign problem is that of removing the modulus brackets. Strictly it is a vector direction problem, but this general case is scarcely covered for the examples relate to molecules where symmetry dictates the direction, but not the choice of the remaining f sign ambiguity.Experiment finds this determination difficult. H/D isotopic substitution and/or understanding the intensity modification associated with Coriolis coupling may give relative signs. Absolute signs are even more difficult and require a molecule with a non-zero dipole moment. Success with approaches (b), (c) and ( d ) below may provide easier solutions. Here each bond in the molecule is assigned a dipole moment parallel to itself that changes direction with bond bending and magnitude if the bond changes length. The associated parameters were introduced by Russian workers and are favoured in this volume in the contributions by Zerbi and Gussoni.Any given molecule may have more such parameters than there are observed intensities, but a set of parameters can be extracted from chemically related molecules. These prove to be fairly transferable to further molecules for predictions. (c) Atomic polar tensors. This approach is favoured by Person and King. The scalar para- meters of this approach are typified by apz/aya, which is the change of the x component of the dipole as the a atoiii moves in the y direction. There are 3% of these for an n-atom molecule, although with symmetry there will be numerous relationships between them and with the over-all dipole moment whose components in laboratory space vary as the molecule rotates. There is an important quantity, independent of the axis choice, which sums the nine terms of the form (&53c/i3ya)2 for a given atom a; this may be written 3Xz and as x, has the dimensions of a charge it may be taken as an “effective,’ atomic charge.A sum over all atomic xi, with coefficients involving masses and geometry only, gives an intensity sum. Any of these parameters, including @/aQ, itself , can be obtained from a wave-function treatment. Usually the molecules are too large for a full ab initio treatment but many of the simpler, and therefore less expensive in computer time, approaches have been (b) Electro-optical pavavlzeters. (d) Theoretical calculations,December, 1983 BOOK REVIEWS 1541 examined and found to be useful; CNDO is found to be useful especially for a simple prediction of sign and approximate values.This review has not emphasised experimental features, the evaluation of normal co-ordinates, the analogous problems in Raman intensities or an empirical approach relating parameters to Hammett constants, although all these and other items are covered. Analytical chemists will wish to know if the accuracy of any treatment is such as to be acceptable for avoiding calibration work. A t present any treatment that predicts sign and magnitude to 20% is considered good. More typical is the attempt in Table 14.8 to predict CF,C1 intensities by transference from CH,, CH,F and CH,Cl. The six fundamental bands have predicted intensities ( A i ) of 197, 6.0, 0.09, 712, 1.7 and 0.4 compared with measured values of 561, 35, 0, 673, 3.1 and 0 km mol-1, respec- tively.The subject of this volume appears to have a long future. D. H. WHIFFEN HANDBOOK OF CHEMICAL MICROSCOPY, VOLUME 1. Fourth Edition. By CLYDE WALTER MASON. Pp. xviii + 505. Wiley - Interscience. 1983. Price L62.25. ISBN 0 471 57531 3. I t is now over 50 years since the First Edition of Chamot and Mason’s “Handbook of Chemical Microscopy” appeared. Although published under joint authorship, Volume 1 was largely the work of Mason and Volume 2 of Chamot. We now have the Fourth Edition of Volume 1, which has become a standard work, and this time it has been published under the sole authorship of Clyde W. Mason. Then Volume 1 had been completely revised and brought up to date even to the extent of including mid-1958 references.The 1983 version has not received the same measure of updating, although i t has an altered appearance. The typeface has changed and although many of the diagrams from Volume 3 have been used they benefit from the removal of unnecessary hatching and shading and are now more clearly labelled. The chapter headings are unchanged but there is the addition of a short (7-page) final chapter entitled “Microscopic Qualitative Chemical Analysis,” the material for this coming from Volume 2 of the previous edition. The chapter on electron microscopy has been extended, there are some new references, three pages devoted to scanning electron microscopy have been added and the chapter is illustrated by light, transmission and scanning micrographs (mainly concerned with wood structure).A large pro- portion of the text is a verbatim reprint of the 1958 edition with very minor editorial changes and the addition of a few (not always up-to-date) references. This is to be welcomed in the chapters dealing with the theory of light microscopy and polarisation phenomena because basic principles remain the same and the author’s style is lucid, making the handbook very readable. However, light microscopy has advanced since 1958 and this calls for an updating of the text. In the 1950s phase contrast microscopy was new and the 1958 edition gave an excellent account of the technique, which justifiably remains unchanged in the present edition. However, an indirect result of Zernike’s work on phase contrast was the development of different types of inter- ference microscopes.These are now being used by the chemists and materials microscopists for whom this volume is intended and yet there is no reference to interference microscopy. The section on fluorescence microscopy also duplicates that of the earlier edition, with no mention of incident light fluorescence (epifluorescence) which was developed by Ploem in 1967 and is now widely available. The chapters covering the preparation of material for the microscope and photomicrography contain much useful information, but modern techniques and materials have been neglected. Both the dust-jacket and preface claim that this new edition includes “considerably expanded material on the properties of crystals and aggregate structures.” Excellent as the writing is on this topic, the text follows that of the earlier edition very closely, the only expansion being the addition of a diagram and a few new references. The later chapters deal with microscopic measurements, particle size determination and quantita- tive analysis.Here there has been some attempt to update the previous edition but key references are missing and there is no mention of automatic or semi-automatic image analysis. Had this volume been published in the form of a reprint of the Third Edition the reviewer would now be recommending the purchase of a well written classic with something to teach every practising microscopist. It is more difficult to make that recommendation when the volume purports to be fully revised and updated, which sadly it is not. It is interesting to compare this new edition with the Third Edition, published in 1958.A reading of this new Volume 1 reveals many similarities with its predecessor. F. OLGA FLINT1542 BOOK REVIEWS Analyst, Vol. 108 METHODS FOR THE DETERMINATION OF HAZARDOUS SUBSTANCES. By HSE COMMITTEE ON Health and Safety Executive, Occupational Medicine MDHS 1-MDHS 14 and 16-21. These methods are the first 20 in a series being published by the Health and Safety Executive Committee for Analytical Requirements that can be used to measure exposure levels to toxic substances in the workplace. Each method covers a particular compound or element and can be purchased separately, some a t 50p and others at L1.00, a reasonable sum to pay to avoid time-consuming method development. Many analysts and industrial hygienists will purchase all of the methods to be used as a ready source of reference and it is to be hoped that the HSE will consider publishing batches of, say, 25 methods in book form for this purpose. The contents of the methods are comprehensive, giving not only all practical details necessary to carry out the measurements but also useful paragraphs on properties, toxicity and first aid relating to the hazardous substance being measured. Of particular value are the two methods describing the generation of test atmospheres for calibration purposes, often the most difficult paxt of ensuring accurate results from monitoring exercises.I t is interesting that the HSE have produced a protocol for validation of diffusive samplers but have not yet produced a method using a diffusive device.Statements such as “Overall precision should be better than 10% provided the pump error is within f5% and the bias of the method is expected to be better than 50/0” do not give one much conviction that the method has been fully evaluated. Despite this there is no doubt these methods will be welcomecl by anyone who is involved in monitoring workplace atmospheres. ANALYTICAL REQUIREMENTS (CAR). and Hygiene Laboratories, London. A full list appears in Analytical Proceedings, 1983, 20, 540. This should be rectified as soon as possible. The validation of some of the methods leaves much to be desired. G. E. PENKETH ANNUAL REPORTS ON NMR SPECTROSCOPY, VOLUME 14. Edited by G. A. WEBB. Pp. viii + 406. Academic Press.1983. Price L54.60; $90. ISBN 0 12 505314 2. ISSN 0066 4103. This volume is merely a table of all fluorine chemical shifts published in the years 1979-81 and collected by V. Wray. Where known, spin - spin coupling constants involving the 19F nucleus are quoted. There are 844 references mostly referring to the main tables, which relate t o over 4 000 compounds, b u t there are a few other entries relating to relaxation times or polymers that are listed in subsidiary tables or text. The table arrange- ment t3kes some time to get used to if special compounds are sought, but the impression is certainly one of completeness in the organic and inorganic fields. This is not a book which one can, in the normal sense, review, but perhaps one may hope that computer compilation may soon take over this tabulation and in particular coalesce this new information with that in Volume 10B of this series covering 1976-78 into a single arrangement.Hopefully such a compilation will always remain up-to-date, and be accessible world-wide a t a reasonable cost. D. H. WHIFFEN All shifts are referred to CFCl, as origin. DRUG METABOLITE ISOL,ATICi\J AND DETERMINATION. Edited by ERIC REID and J. P. LEPPARD. Pp. xii + 289. Plenum. This book, which isa collection of lectures given a t Surrey University a t the 4th Bioanalytical Forum in 1981, contains much useful information on the problems associated with measuring and purifying drugs and metabolites and rather less on their identification. As with any book of this type, the problem comes in pinpointing the relevant information when the need arises.The Editor, whose idiosyncratic comments appear throughout the text, has chosen t o split the indexing into two : one dealing with general topics and the second based on generic names. This latter method, which is intended to link compounds of similar chemical type, fails to achieve its aim and is com- plicated to use. It would have been so much easier if these named compounds had been included in the general index. Apart from this criticism, the book gives an insight into many of the drug metabolist’s difficulties in recovering minute amounts of a specific chemical from the myriad of others in a biological Methodological Survey5 in Biochemistry and Analysis, Volume 12, 1983. Price $42.50. ISBN 0 306 41265 9.December, 1983 BOOK REVIEWS 1543 matrix.Helpful hints can be found in the individual case histories that cover a wide range of drugs and related chemicals. Most of the contributions are low on theory and high on practicality, so will appeal especially to people working in industrial drug metabolism departments. Current methodology is reflected in the large number of articles on HPLC, which range from the work-up of samples for preparative chromatography to the various means employed for the detection of compounds in column eluents. Other techniques, TLC, HPTLC, GLC and immunoassay, are also touched upon. A section is devoted to the difficult area of isolation and identification of Phase I1 metabolites and there are analytical methods described for a variety of structural types.On balance, the book will be a useful addition to drug metabolism bookshelves and will provide a detailed source of practical techniques. For future volumes, I can only reiterate my plea to the Editor to include a comprehensive and simple to use means of accessing the multitude of information to be found in such a book. T. R. MARTEN ENLARGEMENT AND COMPACTION OF PARTICULATE SOLIDS. Edited by NAYLAND G. STANLEY- WOOD. Butterworths Monographs in Chemical Engineering. Pp. x + 294. Butterworths. 1983. Price k25. ISBN 0 480 10708 1. Dr. Nayland G. Stanley-Wood has used his position as Editor to collect a galaxy of distinguished authors covering a wide range of subjects under the general title of this monograph. The matters covered include the characterisation of powders and granules before and after compaction, mixing, shear testing, fluidised-bed granulation, mechanisms of size enlargement and compaction and the instrumentation of industrial presses and industrial processes.The approach is inter-disciplinary drawing upon the experience and wisdom of chemical engineers, physicists, powder and pharma- ceutical technologists, ceramicists and metallurgists. The idea of bringing all these subjects together arises from the highly successful post-experience courses held in 1979, 1980 and 1982 on the Compaction of Particulate Solids held a t the University of Bradford and sponsored by the Institution of Chemical Engineers in their programme of continuing education, The Editor appropriately presents the first chapter in the book on the particle characterisation by size, shape and surface for individual particles.In this opening chapter he sets out the rigid definitions that are so essential in the description of powder assemblies. The main methods of particle sizing are also outlined in this chapter, the use of image forming instruments, mechanical sieving, gravity sedimentation, centrifugal sedimentation, attenuation diameter, scattering diameter and electrical resistance diameter. Dr. Stanley-Wood also contributes the second chapter on particle characterisation by size, shape and surface for contacted particles. Properties discussed in this chapter include the various forms of density determination, gaseous adsorption methods, the pre-size distribution calculation and mercury penetration methods.The application of the nitrogen- adsorption method and mercury intrusion to compacted solids is given a special treatment. A later chapter on compact characterisation is also presented by Dr. Stanley-Wood. The fundamental property to be considered here is the strength. However, in succeeding parts of this chapter he deals with soil mechanics, volume reduction in undimensional consolidation and the compaction process. Powder mixing is dealt with by N. Harnby in Chapter 3. This is a short chapter dealing with free- flowing mixtures and cohesive mixtures. The mechanisms of size enlargement are adequately dealt with by P. J. Lloyd. He relates these mechanisms to the common methods of granulation. The material dealing with the flow and handling of solids and the design of solid-handling plants is presented by J .C. Williams. It is interesting that the special problems associated with pharmaceutical granulation and com- paction is introduced by B. Hunter, followed by more general treatises on mechanisms of compac- tion by J . J . Benbow and fluidised-bed granulation by A. W. Nienow. This is followed by more specialised material, namely the instrumentation of tablet machines by H. S. Thackers, compaction of ceramics by H. M. MacLeod and isostatic pressing and compacting techniques by D. E. Lloyd, I. K. Bloor and R. D. Brett. This arrangement could be criticised but putting this comment aside the detailed consideration of each of these chapters is very much on the credit side. B. Hunter in dealing with pharmaceutical granulation identifies compaction problems related to the pharmaceutical industry and then outlines the solutions.The contribution by J. J . Benbow on mechanisms of compaction is interesting in that it focuses attention on the needs of the catalyst industry although the information is equally valuable elsewhere. Fluidised-bed granulation is given an excellent strictly mathematical outline by A. W. Nienow. It is a subject that could be1544 BOOK REVIEWS expanded considerably. It is always difficult to assess chapters on instrumentation because equipment is out of date so quickly but H. S. Thacker has side-stepped this issue by taking a general look at the subject. There are special problems associated with ceramics, not the least being the subsequent treatment] e.g., heat treatment, that the material will undergo.The subject is treated by H. M. MacLeod in a direct manner and some beautiful electron micrographs are presented. The final chapter on isostatic pressing and compaction techniques is, as already noted, a collaborative effort where the advantages of isostatic pressing relative to other shaping methods are discussed. Overall, the book is well presented, in a field where information of this kind is needed and the references at the end of each chapter will allow the reader to find more detailed information, which is as it should be. D. DOLLIMORE NMR OF AROMATIC COMPOUNDS. By J. D. MEMORY AND NANCY K. WILSON. Pp. xiv + 252. Wiley-Interscience. 1982. Price L33. ISBN 0 471 08899 4. As one who in the period 1945-55 was quite knowledgeable about the infrared spectroscopy of aromatic compounds and what the technique could do for organic chemists, it was with great interest that this reviewer opened this book.Indeed his review had been mentally planned to discuss the ease of determining the location of ring substituents or their electronegativity influences by means of spin - spin coupling constants] 13C chemical shifts and other NMR parameters compared with the use of infrared frequencies. However, the book was far too much of an undigested biblio- graphic compilation to make this approach realistic. The first chapter covers NMR theory and molecular orbital theory to a depth found in many text-books. There follows a more detailed theory of chemical-shift calculations, introducing vector potentials.A range of detailed techniques and of approximations including ring current approaches is mentioned but with 65 references to 21 pages of text this forms a guide for further reading rather than a full account. Chapter 3 is very different in style and consists of tables of 1H and 19F chemical shifts and Chapter 4 has similar tabulation for 13C and for 15N and 1’0 in heterocyclic positions. The space is extravagantly used ; a picture of anthracene with positions 1, 2 and 9 indicated hardly needs to be followed by three separate diagrams for 1-F, 2-F and 9-F substituted anthracene. Much information is repeated, for example the experimental chemical shift of 2-H in triphenylene is given as 9.58 (surely a misprint) in Table 3.1, as 0.31 referenced to benzene at 7.27 in Table 3.2 and as 7.58 p.p.m. in Table 3.3. There is very little text associated with these tables and no real discussion of the interesting negative 6, as low as -5.49 p.p.m. for the central hydrogens lying out of the major ring plane in trans- 15,16-dihydropyrene. While correlation graphs showing regularities are introduced they are not always well explained, being taken out of context. Figure 3.5 plots “6calc. (Hz)” against ‘‘60bS. (Hz a t 100 MHz)” according to the axis labelling: the caption indicates that this shows the correlation of shift with ui and or. Hitherto u has stood for the calculated chemical shift, although this reader suspects that these ui and refer to Hammett constants or something similar. Chapter 5 has nine pages of theory and further tables showing calculated and experimental J , including those for 13C,13C and 13C,lH couplings. Again structural diagrams from Chapters 3 and 4 are repeated, with different identifying numbers. It amounts to a good bibliography relating to a lot of processes, especially intramolecular flexibility. The final chapter covers modern instrumentation ; quite a useful compilation but not specially related to aromatics. Indeed, Table 7.2 relating to chemical shifts of 13C with lanthanide reagents does not include a single aromatic compound. While what is written is reasonable, if sometimes slipshod, it is a collection of facts rather than a balanced account of the NMR of aromatic compounds. It is certainly doubtful if it is “geared to the information needs of . . . analytical chemists,” so that it “will be a frequently consulted reference”; this is the claim of the blurb on the cover. Chapter 6, possibly the best, covers relaxation times and also dynamic processes. D. H. WHIFFEN

ISSN:0003-2654    

DOI:10.1039/AN9830801538

出版商:RSC    

年代:1983

数据来源: RSC

摘要:

Analyst, December, 1983 INSTRUCTIONS TO AUTHORS 1545 The Andyst publishes papers on all aspects of the theory and practice of analytical chemistry, fundamental and applied, inorganic and organic, including chemical, physical and biological methods. Papers may be submitted for publication by members of The Royal Society of Chemistry or by non-members. There is no page charge for papers published in The Analyst. The following types of papers will be considered : FMZZ papers, describing original work. Short papers, also describing original work, but shorter and of limited breadth of subject matter ; there will be no difference in the quality of the work described in full and short papers. Communications, which must be on an urgent matter and be of obvious scientific importance. Rapidity of publication is enhanced if diagrams are omitted, but tables and formulae can be included.Communications should not be simple claims for priority: this facility for rapid publica- tion is intended for brief descriptions of work that has progressed to a stage at which it is likely to be valuable to workers faced with similar problems. A fuller paper may be offered subsequently, if justified by later work. facet of analytical chemistry. Reviews, which must be a critical evaluation of the existing state of knowledge on a particular Every paper (except Communications) will be submitted to at least two referees, by whose advice the Editorial Board of The Analyst will be guided as to its acceptance or rejection. Papers that are accepted must not be published elsewhere except by permission.Submission of a manuscript will be regarded as an undertaking that the same material is not being considered for publication by another journal. Copyright. The whole of the Literary matter (including tables, figures, diagrams and photo- graphs) in The Analyst is copyright and may not be reproduced without permission from the Society or such other owner of the copyright as may be indicated. For the benefit of potential contributors outside the United Kingdom, a Panel of Regional Advisory Editors exists. Requests for help or advice on any matter related to the preparation of papers and their submission for publication in The Analyst can be sent to the nearest member of the Panel. Currently serving Regional Advisory Editors are listed in each issue of The Analyst.Manuscripts. Papers should be typewritten in double spacing on one side only of the paper. Three copies of text and illustrations should be sent to the Editor, The Aqalyst, The Royal Society of Chemistry, Burlington House, London, W1V OBN, and a further copy retained by the author. Proofs should be carefully checked and returned immediately (by Air Mail from outside Europe). if ordered at the time of publication. Regional Advisory Editors. Proofs. The address to which proofs are to be sent should accompany the paper. Reprints. Fifty reprints of each paper are supplied free. Additional reprints can be purchased Details are sent to authors with the proofs. Notes on the Writing of Papers for The Ana/yst Manuscripts should be in accordance with the style and usage shown in recent copies of The Conciseness of expression should be aimed at: clarity is increased by adopting a logical Analyst.order of presentation, with suitable paragraph or section headings.1546 INSTRUCTIONS TO AUTHORS Analyst, Vo,?. 108 Descriptions of new methods should be supported by experimental results showing accuracy, precision and selectivity. The recommended order of presentation is as indicated below : Title. This should be as brief as is consistent with an adequate indication of the original features of the work. The analytical method used in the work should be mentioned in the title. Synopsis. A synopsis of about 100 words, giving the salient features and drawing attention to the novel aspects, should be provided.Keywords. Up to 5 keywords, indicating the topics of importance in the work described, should be included after the synopsis. Aim of investigation. An introductory statement of the object of the investigation with any essential historical background, followed , if necessary, by a brief account of preliminary experimental work. Description of the experimental procedures. Working details must be given concisely. Analytical procedures should preferably be given in the form of instructions; well known operations should not be described in detail. Results. These are best presented in tabular form, followed by any statistical evaluation, which should be in accordance with accepted practice. Discussion of results. This section will comment on the scope of the method and its validity, followed by a statement of any conclusions drawn from the work.Nomenclature. Current internationally recognised (IUPAC) chemical nomenclature should be Common trivial names may be used, but should first be defined in terms of IUPAC nomen- used. clature. SI w i t s . The SI system of units should be used. These units are summarised in the Appendix. The effect on current style of papers for The Analyst includes the following: (a) dimensions should preferably be given in metres (m) or in millimetres (mm) ; (b) temperatures should be expressed in K or “C (not OF) ; (c) wavelengths should be expressed in nanometres (nm) (not mp) ; (d) frequency should be expressed in Hz (or kHz, etc.), not in c/s or c.P.s.; rotational frequency can be denoted by use of s-1; (e) radionuclide activity will be expressed in becquerels (Bq) or curies (Ci) ; 1 Ci = 3.7 x 1O1O Bq; (f) the micron (p) will not be used; 10-6 m will be 1 pm.Abbreviations. SI units should be used. Normality and molarity are generally expressed as Abbreviational full stops are omitted after the common decimal fractions (e.g., 0.02 N, 0.375 M). contractions of metric units (e.g.D ml, g, pg, mm) and other units represented by symbols. Abbreviations other than those of recognised units should be avoided in the text; symbols and formulae are not used instead of the names of elements and compounds in the text, but may be used in addition to names when they are necessary to avoid ambiguity, e.g., to specify crystalline composition, as in CuS04.5H,0, to show structure or in equations.Percentage concentrations of solutions should be stated in internationally recognised terms. Thus the symbols “m” for mass and “v” for volume are to be used instead of ‘*ws’ for weight and “v” for volume. The following show the manner of expressing these percentages together with an acceptable alternative given in parentheses: m/m (g per 100 g) ; yo m/V (g per 100 ml) ; yo V / V . Further implications of the use of the term “mass” are that “relative atomic mass” of an element (A,) replaces atomic weight, and “relative molecular mass” of a substance (M,) replaces molecular weight.December, 1983 INSTRUCTIONS TO AUTHORS 1547 Concentrations of solutions of the common acids are often conveniently given as dilutions of the concentrated acids, such as “dilute hydrochloric acid (1 + 4),” which signifies 1 volume of the concentrated acid mixed with 4 volumes of water.This avoids the ambiguity of 1 : 4, which might represent either 1 + 4 or 1 + 3. Dilutions of other solutions can be expressed in a similar manner. Tables and diagrams. The number of tables should be kept to a minimum. Column headings No Tables must be supplied with titles and be so should be brief. lines should be ruled in tables in the manuscript. set out as to be understandable without reference to the text. Tables consisting of only two columns can often be arranged horizontally. Either tables or graphs may be used but not both for the same set of results, unless important The information given by a straight-line calibration additional information is given by so doing.graph can usually be conveyed adequately as an equation or statement in the text. The style used in headings to tables and in labels on the axes of graphs, where the numbers The diagonal line (solidus) will not be In accordance with the SI system, units such as grams per millilitre are For a table (or graph), this would appear as: Concentration It should be noted that the “combined” unit, g ml-l, must not have any “in- To express concentration in grams per 100 millilitres, the word “per” will still It may be preferable for an author to express concen- represent numerical values, is, for example: Volume/ml. used to represent “per.” already expressed in the form g ml-l. of solution/g ml-l. trusive” numbers. be required: Concentration/g per 100 ml.trations in grams per litre (g 1-l) rather than grams per 100 ml. Most diagrams will be retraced and lettered in order to achieve uniform line thicknesses and lettering size and style, so it is not essential to prepare specially traced drawings. However, all diagrams should be carefully and clearly drawn on good quality paper and should be clearly lettered. If possible, complicated flow charts, circuit diagrams, etc., should be supplied as art- work for direct reproduction in order to avoid time-consuming and expensive redrawing. Three sets of illustrations should be provided, two sets of which may be made by any convenient copying process for transmission to the referees. All diagrams should be accompanied by a separately typed set of captions.Wherever possible, extensive identifying Iettering should be placed in the caption rather than on lines on graphs, etc. Photographs. Photographs should be submitted only if they convey essential information that cannot be shown in any other way. They should be submitted as glossy or matt prints made to give the maximum detail. Colour photographs will be accepted only when a black-and-white photograph fails to show some vital feature and can be supplied either as prints or transparencies. References. References should be numbered serially in the text by means of superscript figures, e.g., Godden and Thomerson,’ Burns et aZ.2 or Hirozawa,S and collected in numerical order under “References” at the end of the paper. They should be listed, with the authors’ initials, in the following form (double-spaced typing) : 1.2. 3, Godden, R. G., and Thomerson, D. R., AnaZyst, 1980, 105, 1137. Burns, D. T., Glockling, F., and Harriott, M., J . Chromatogr., 1980, 200, 305. Hirozawa, S. T,, in Kolthoff, I . M., and Elving, P. J., Editors, “Treatise on Analytical Chemis.try,” Part 11, Volume 14, John Wiley, New York, 1971, p. 23. Journal titles should be abbreviated according to the Chemical Abstracts Service Source Index (CA SSI) . For books, the edition (if not the first), the publisher and the place and date of publication should be given, followed by the page number. Authors must, in their own interest, check their lists of references against the original papers; The number of references must be kept second-hand references are a frequent source of error.to a minimum.1548 INSTRUCTIONS TO AUTHORS Appendix The SI System of Units In the SI system there are seven base units- Physical quantity length mass time electric current thermodynamic temperature amount of substance luminous intensity Name of unit metre kilogram second ampere kelvin mole candela Analyst, Vol. 108 Symbol for unit m kg S A K mol cd There are two supplementary dimensionless units for plane angle (radian, rad) and solid angle (steradian, sr). Some derived SI units that have special names are as follows- Physical Name Symbol Definition quantity of unit for unit of unit energy force power quantity of electricity electric potential difference electric resistance electric capacitance frequency magnetic flux density radionuclide activity (magnetic induction) joule newton watt coulomb volt ohm farad hertz tesla becquerel Examples of other derived SI units are- Physical quantity area volume density velocity angular velocity acceleration magnetic field strength iI W C V ct F HZ SI unit square metre cubic metre kilogram per cubic metre metre per second radian per second metre per second squared ampere per metre kg s - ~ A-l S'1 Certain units will be allowed in conjunction with the SI system, e.g.- Physical quantity volume magnetic flux density temperature, t radionuclide activity energy (magnetic induction) Name Symbol of unit for unit litre 1 gauss G degree Celsius OC curie Ci electronvolt eV Symbol for unit ma ma kg m-' m s-1 rad s-1 m s-I A m-1 Definitiolr of unit 10-8 m8 = 1 dms 10-4 T t/"C = T/K-273.16 3.7 x 10lOBq 1.6021 x lo-" J The common units of time (e.g., minute, hour, day) and the angular degree (") will continue to be used in appropriate contexts. Decimal multiples and submultiples have the following names and symbols (for use as prefixes)- 10-8 milli m 108 kilo k 10-6 micro p 10' mega M lo-@ nano n 109 gigs G 10-1s p1co P 10" tera T 10'6 Pets P 101' exa Compound prefixes (s.g., mpm) should not be used: 10-9 m = 1 nm.

ISSN:0003-2654    

DOI:10.1039/AN9830801545

出版商:RSC    

年代:1983

数据来源: RSC