摘要:

ANALYST, JANUARY 1989, VOL. 114 105 Solvent Extraction Separation of Cerium(ll1) from Transition Elements With 15-Crown-5 With Picrate as the Counter Ion Nandkumar V. Deorkar and Shripad M. Khopkar" Department of Chemistry, Indian Institute of Technology, Bombay 400 076, India Cerium(ll1) was quantitatively extracted between pH 6.0 and 8.0 with 0.05 M 15-crown-5 in dichloromethane from 0.01 M picric acid with picrate as the counter ion. Cerium(ll1) was stripped with 1 M perchloric acid and determined spectrophotometrically at 655 nm as its complex with Arsenazo Ill. Cerium was separated from a large number of elements. Stepwise extraction of cerium permits its separation from thorium, uranium, scandium, yttrium and strontium. The method was applied to the determination of cerium in monazite sand.Keywords: Cerium determination; solvent extraction; crown ethers; actinide elements; spectrophotornetry The macrocyclic polyether 15-crown-5 and its substituted derivatives such as 4-tert-butylcyclohexyl-15-crown-5 have been used in conjunction with didodecylnaphthalene- sulphonic acid (HDDNS) for the synergistic extraction of cerium(II1). 1 Among the lanthanoids, europium has been extracted with 18-crown-6, benzo-15-crown-5 and dibenzo-18- crown-6.2 However, no attempts have been made to extract other lanthanides with crown ethers. Among the actinides, thorium and uranium have been extracted with dicyclohexyl- 18-crown-6 and dicyclohexyl-24-crown-8. However, system- atic investigations into the solvent extraction of cerium(II1) are lacking. This paper describes such studies.Experimental Apparatus A Type 822 digital pH meter (ECIL, India), a Model G5866C spectrophotometer (ECIL) with a 10-mm mat6hed Corex glass cuvette and a wrist-action flask shaker (Toshniwal, India) were used. Reagents Ceriurn(lZZ) solutions. A stock solution ( 5 mg ml-1) containing cerium(II1) was prepared by dissolving 1.80 g of cerium(II1) nitrate in 100 ml of water containing 1% nitric acid. A solution containing 25 pg ml-1 of cerium(II1) was prepared by appropriate dilution. Picric acid solution, 0.05 M. Solutions of crown ethers, 0.05 M. Prepared by dissolving appropriate amounts of 15-crown-5 (15C5), 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and dibenzo-18- crown-6 (DB18C6) (Aldrich) in dichloromethane. General Procedure To an aliquot of a solution containing 15 pg of cerium(II1) picric acid was added to give a concentration of 0.01 M in a total volume of 10 ml.The pH of the resulting solution was adjusted to 6 8 with 0.01 M picric acid or lithium hydroxide solution. Then the solution was transferred into a separating funnel and 10 ml of a 0.05 M solution of the appropriate crown ether in dichloromethane were added. The solution was shaken on a wrist-action flask shaker for exactly 10 min and the two phases were allowed to settle and separate. The organic phase was equilibrated with 10 ml of 1 M perchloric acid for 10 rnin to back-extract the cerium(II1). Cerium was determined in the aqueous phase spectrophotometrically as its * To whom correspondence should be addressed.Arsenazo 111 complex at 655 nm. The amount of cerium present was calculated from a calibration graph. Results and Discussion Effect of pH The optimum pH for the quantitative extraction of cerium(II1) was ascertained by extracting it with 0.05 M solutions of crown ethers at various pH. The phase ratio was kept at 1 : 1. The optimum pH was 6 8 when 15C5 was used as the extractant but the extraction was incomplete with the other crown ethers, the maximum being 63% with 18C6, 46% with DB18C6 and 81% with DC18C6 at pH 7.0 (Fig. 1). Therefore, 15C5 was used as the extractant at pH 6 8 in subsequent work. The amount of unextracted cerium in the aqueous phase was ascertained using the same spectrophotometric method by calculating the distribution ratio ( D ) .Effect of Concentration of Crown Ether The optimum concentration of 15C5 was determined by extracting cerium(II1) with 10 ml of various concentrations of crown ethers (1.0 x 10-1-10 X 10-2 M) (Table 1). The extraction was also carried out with various volumes (2.5-20 ml) of 5.0 x 10-2 M 15C5. The extraction was 80% with 10 ml of 4.0 X 10-2 M 15C5 whereas it was quantitative with 10 ml of 5.0 x 10-2 M 15C5. The extraction was incomplete with 2.5-7.5 ml of 5 x 10-2 M 15C5 but it was quantitative with 10 ml of 5.0 X 10-2 M 15C5. Therefore, the optimum volume and concentration of the crown ether were 10 ml of a 5.0 x 10-2 M solution of 15C5 in dichloromethane. Effect of Concentration of Picric Acid The optimum concentration of picric acid for quantitative extraction was ascertained by extracting cerium(II1) with various concentrations of picric acid in the range 1.0 X 100 A f--+ " 2 3 4 5 6 7 8 PH Fig.1. 18C6; and D, DB18C6 Extraction as a function of pH. A, 15C5; B, DC18C6; C ,106 ANALYST, JANUARY 1989, VOL. 114 Table 1. Effect of concentration of 15C5 on extraction Concentration of 15C5/10-2 M Extraction, "/" D Table 4. Effect of back-extraction agents 1 .O 2.0 3.0 3.5 4.0 4.5 5.0 10.0 16 0.19 50 2.0 76 3.16 78 3.5 80 4.0 86 6.2 100 X 100 X Table 2. Effect of counter ions on extraction Concentration/ Counter ion 1@'M Extraction, Yo D Picricacid . . . . 2.0 5.0 7.0 10.0 Dipicrylamine . . 2.&10.0 Eosin . . . . . . 2.@10.0 Metanil yellow . . 2.0-10.0 Benzenedisulphonic acid . . . . . . 2.0-10.0 18 0.21 75 3.00 92 11.5 100 x - 0 0 0 - - Table 3.Extraction achieved with different solvents Dielectric Solvent constant Extraction, o/o Benzene . . . . 2.28 32.0 Toluene . . . . 2.30 44.0 Xylene . . . . . . 2.38 40.0 Carbon tetrachloride 2.24 27.0 Chloroform . . . . 4.80 97.8 Dichloromethane . . 9.08 100.0 1,2-Dichloroethane 10.50 86.0 Nitrobenzene . . 34.80 61 .o D 0.47 0.78 0.66 0.36 44.45 6.14 1.56 cc 10-3-10.0 x 10-3 M. As picric acid gives planar complexes, picrate is the preferred counter anion.3 Attempts were made to use other counter ions such as benzenedisulphonic acid, eosin, dipicrylamine and metanil yellow, but these were unsuccessful (Table 2). The extraction was incomplete below 7.0 X 10-3 M but quantitative above 8.0 x 10-3 M picric acid, hence 1.0 x 10-2 M picric acid was adopted.Choice of Solvent Benzene, toluene, xylene, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane and nitrobenzene were used as solvents for 1SC5 in the extraction of cerium(II1) (Table 3). Dichloromethane was found to be the best solvent. Effect of Back-extraction Agents Cerium was back-extracted with 10 ml of various concentra- tions of different back-extraction agents in the concentration range 0.1-6 M (Table 4). Perchloric acid (1-6 M) gave the best results and sulphuric and nitric acids (3-6 M) were also successful. It was necessary to use higher concentrations of hydrochloric acid for this purpose. Acetic acid was ineffective. Therefore, 10 ml of 1 M perchloric acid were adopted for back-extraction. Effect of Time of Equilibration The solution was shaken on a wrist-action flask shaker for various times from 2 to 20 min and the extraction was found to be 100% on shaking for 10 min or longer.Hence the optimum time for equilibration was 10 min. Effect of Varying Metal Ion Extraction Various amounts of cerium were extracted with 10 ml of 5.0 x 10-2 M 1SC5 in dichloromethane at pH 6.0. Extraction was Back- Extraction, '70 extraction agent 0 . 1 M 0 . 2 5 ~ 0 . 5 M 1 M 2M 3M 4M 5M 6 M HC1 . . . . 20 20 37 48 37 65 98 100 100 HNO, . . 36 36 50 67 72 100 100 100 100 HC104 . . 40 44 60 100 100 100 100 100 100 H2SOJ . . 33 39 53 68 96 100 100 100 100 CH,COOH 0 0 0 0 13 31 63 76 78 Table 5. Effect of concentration of metal ion Amount of Amount of CeT1I taken/ Ce"' found/ FLg Extraction, "/o D 2.0 5.0 10.0 15 .0 20.0 30.0 40.0 45.0 50.0 1.8 5.0 10.0 15 .O 20.0 30.0 39.7 41.4 42.0 90.0 100.0 100.0 100.0 100.0 100.0 99.25 92.0 84.0 9 X cc X x x 132.33 11.5 5.25 Table 6.Effect of foreign ions Li+ Na+ K+ Mg2+ Ca2 + Ba2+ Sr2+ Pb2+ Zn2+ Cd2+ La3+ Nd3+ SC'+ Y? + Ti47 Zr4+ Hf4+ Thj+ UO,*+ I- . . CI - NO3- c104- . . CH3COO ~ soj2- . . Tartrate Ascorbate Citrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . Added as . . LiCl . . NaCl . . KCI . . MgSO4.7H2O . . CaC1,.6H20 . . Ba(N03)2.4H,0 . . Sr(N03),.2H20 . . ZnCI, . . 3CdS04.8H20 . . La(NO3)?.6H2O . . Pb(N03)Z . . Nd(NO,)?.GHZO ' . Sc(N03)3 " Y(N03)3 . . Ti(S04)2 . . Zr(N03),.4H,0 . . Th(N03),.4H20 . . HI . . HCI . . HN03 . . HC104 . . Hf(S04)Z . . U02(N03)2.6H,O . . CH,COOH . . Tartaricacid . . Ascorbicacid . . Citricacid . . H2SO4 Tolerance limit/ mg 6.00 0.05 0.07 0.80 0.40 0.09 0.60 1.30 1 .so 1 .00 1.10 0. 50 0.50 0.45 0.55 0.46 0.62 0.50 1.20 5.00 5 . 00 4.60 3. 50 6.00 2.50 1.30 0.90 0.70 quantitative up to 40 pg of cerium per 10 ml of solution but decreased above this concentration. Hence the optimum concentration for quantitative extraction was 5-40 pg ml-1 of cerium(II1) (Table 5 ) .Nature of Extracted Species The composition of the extracted species was ascertained from a graph of log D versus loglcrown ether] at a fixed picric acid concentration and a graph of log D versus log[picric acid] at a fixed 15C5 concentration. The slopes were 2.2 and 3.1, respectively. The probable composition of the extracted species was cerium : crown ether : picric acid = 1 : 2 : 3. These findings agreed with those of earlier workers.&-hANALYST, JANUARY 1989, VOL. 114 107 Table 7. Separation of cerium(II1) from ternary mixtures Amount Mixture taken/ No. Components pg Extractant 1 Ce"1 30 0.05 M 15C.5 U"' 100 0.02 M DC18C6 S c I I I or y I 1 1 200 Aqueous phase 2 Celli 30 0.05~15CS 100 0.02 M DC18C6 200 Aqueous phase 30 0.05~15CS U"' 100 0.02 M DClSC6 Ca" or SrI' 100 Aqueous phase Medium Picric acid HCl(6M) Picric acid HCl(6M) Picric acid HCl(6 M) (0.01 M) - (0.01 M) - (0.01 M ) - Reagent for determination Arsenazo I11 Arsenazo TI1 Alizarin Red S Arsenazo 111 Arsenazo 111 Arsenazo TI1 Arsenazo 111 Arsenazo I11 Flame emission at 423/460 nm L;,, Jnm 65 5 650 525 6.5.5 650 660 65 5 650 Effect of Foreign Ions Cerium(II1) was extracted in the presence of a number of foreign ions (Table 6).The tolerance was set as the concentra- tion of foreign ion that produced a variation of kO.01 in the absorbance measurement. Such a variation represents an error of about 2.0% in the recovery of cerium(II1). Lithium, halides and nitrate were tolerated in a ratio of 1 : 400 and zinc, uranium, acetate and sulphate in a ratio of 1 : 100.Alkali and alkaline earth metal ions gave a very low tolerance limit. Separation of Cerium from Multi-component Mixtures It was possible to separate cerium from uranium, thorium, scandium, yttrium and strontium, which are normally asso- ciated with it in fission products. The separation was achieved by stepwise extractions under different conditions. Cerium was extracted from a mixture of cerium(III), uranium(V1) and scandium(II1) or yttrium(II1) with 0.05 M 15CS. Then uranium(V1) was extracted from 6 M hydrochloric acid with DC18C6 and stripped with 0.5 M hydrochloric acid. Finally, scandium(IT1) or yttrium(II1) was determined directly in the aqueous phase. Cerium was extracted from a mixture of cerium(III), uranium(V1) and thorium(1V) as described, then uranium was extracted with DC18C6 and thorium was determined directly in the aqueous phase.Finally. cerium was first extracted from a mixture of cerium(ITI), uranium(V1) and strontium(I1) or calcium(I1) with 1SC5 at pH 6.0. Then uranium was extracted with DC18C6 and strontium was determined directly in the aqueous phase by flame emission spectrometry (Table 7). Application to Analysis of Monazite Sand About 1.0 g of monazite sand was dissolved in a mixture of nitric and sulphuric acids. After separating insoluble silica the solution was diluted to 100 ml with distilled water. From an aliquot of a solution containing cerium, thorium, yttrium and calcium, cerium was extracted and determined as described under General Procedure whereas thorium, yttrium and calcium ions were not extracted. Usually small amounts of alkali metals are not co-extracted with cerium, but if their concentration is higher it is possible to eliminate their interference by selective extraction .7 Conclusion The proposed method is simple, rapid and selective.The total time required for separation and determination is 2 h. The separation of cerium from uranium, thorium, scandium or yttrium and strontium is significant because these elements are associated in fission products. The method is applicable to the determination of cerium(II1) in monazite sand. The determi- nation of cerium in gas mantles is also possible. We are grateful to the Council of Scientific and Industrial Research for sponsoring this project and awarding a Junior Research Fellowship to one of us (N. V. D.). References 1. 2. 3. 4. 5 . 6. 7. Ensor, D. D., McDonald, G . R . , and Pippin, C. G., Anal. Chem., 1986, 58. 1814. Hasegawa, Y., and Sakiho, H., Solvent Extract. Ion Exch., 1984, 2, 451. Yoshio, M., and Noguchi, H., Anal. Lett., 1982, A15, 1228. Wang, W . . Chen, B., Jin, Z.-K., and Wang, A , , J. Radioanal. Chem., 1983, 76, 49. Simon, J . D., Moomaw, G. R., and Ceckler, T. M., 1. Phys. Chem., 1985, 85, 5659. Bundi. J . G., Oanh, H. T., and Gillet, B., Znorg. Chrm. Acra, 1981, 53, 219. Mohite, B. S . , PhD TheJiJ, Indian Institute of Technology, Bombay, 1986. Paper 8/01 660G Received April 27th, I988 Accepted September I9th, I988

ISSN:0003-2654    

DOI:10.1039/AN9891400105

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYST, JANUARY 1989, VOL. 114 109 SHORT PAPERS Simultaneous Determination of Nickel, Zinc and Copper by Second-derivative Spectrophotometry Using 1 -(2-Pyridylazo)-2-naphthol as Reagent A. Gallardo Melgarejo, A. Gallardo Cespedes and J. M. Can0 Pavon" Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, 29071 Malaga, Spain A derivative spectrophotometric method, based on the use of second-derivative absorption spectra, has been developed for the simultaneous determination of microgram amounts of nickel, zinc and copper in an aqueous ethanolic medium. The peak to base line measurement technique has been used with good results. Using the proposed method, nickel (0.3-2.0 p.p.m.1, zinc (0.5-3.0 p.p.m.) and copper (0.5-3.0 p.p.m.) in various ratios have been determined with good precision and accuracy.Keywords: Derivative spectrophotometry; second-derivative spectra; nickel determination; zinc determination; copper determination Derivative spectrophotometry is an analytical technique of great utility for extracting both qualitative and quantitative information from spectral curves composed of unresolved bands. In general, the derivative process discriminates against broad bands while emphasising sharper features to an extent that increases with increasing derivative order. However, the use of higher-order spectra is not recommended as a general procedure because the signal to noise ratio becomes progres, sively larger. 1-5 Derivative techniques have been used in pharmaceutical analysis,b environmental analysis7 and in the fingerprint analysis of proteins,* but few data have been published on the determination of mixtures of inorganic ions.Using fifth- derivative spectrophotometry it is possible to determine cadmium and zincs and palladium and platinum.9 A method has been developed for the rapid determination of small amounts of Nd, Ho, Er and Tm in a mixture of lanthanides by third-derivative spectrophotometry with thenoyltrifluoroace- tone.1" The analysis of a mixture of Sm and Eu has also been described" in addition to the determination of zirconium in the presence of hafnium with picramine E.12 This paper describes the simultaneous determination of nickel, zinc and copper ions using 1-(2-pyridyiazo)-2-naphthol (PAN) as the reagent; the prior separation of these metal ions is not necessary.In the normal spectra the bands due to these metal complexes show appreciable overlapping, which pre- cludes their simultaneous determination. However, in the second-derivative spectra each complex shows a separate band. The use of PAN as a reagent in normal spectrophotometry was first described more than 30 years ago; details of this work can be found elsewhere.13-'5 Experimental Apparatus The absorption and derivative spectra were recorded on a Bausch Lomb Spectronic 2000 UV - visible spectro- photometer with 1-cm cells. Derivative spectra were gener- ated by electronic differentiation; the spectrophotometer used had an adequate derivative module so that the first- and second-derivative spectra could be obtained directly. For the pH measurements, a Kilab 1001 potentiometer with a combined glass - calomel electrode was used. * To whom correspondence should be addressed.Reagents All chemicals used were of analytical-reagent grade. Standard solutions of nickel, zinc and copper. Prepared from nickel( 11) nitrate hexahydrate, zinc(I1) sulphate hepta- hydrate and copper(I1) sulphate pentahydrate, respectively, in distilled, de-ionised water. These solutions were standar- dised titrimetrically with ethylenediaminetetraacetic acid (EDTA) . 1-(2-Pyridylazo)-2-naphthol, 0.1% solution in ethanol. Buffer solution, p H 4.8. Prepared by mixing 56.0 g of sodium acetate trihydrate and 25.0 ml of glacial acetic acid and diluting to 1 1 with distilled water. Buffer solution, p H 10.0. Prepared by mixing 67.5 g of ammonium chloride and 570 ml of concentrated ammonia and diluting to 1 1 with distilled water. Recommended Procedure To an aliquot of the sample solution, containing 15-50 pg of nickel, 15-60 pg of zinc and 15-75 pg of copper, in a calibrated flask, add 5 nil of 0.1% PAN solution in ethanol, 10 ml of ethanol and 5 ml of the pH 4.8 acetic acid - sodium acetate buffer and dilute to the mark with distilled water.Record the second-derivative absorption spectra in the range 500-610 nm against a blank solution prepared in the same way. Measure the distances between the base line and the peaks of the derivative curves corresponding to nickel, zinc and copper at 545, 557 and 595 nm, respectively. For preparation of the calibration graphs, record the second- derivative absorption spectra for various known amounts of nickel, zinc and copper under the conditions given above. Construct the graphs as shown in Fig.3. Results and Discussion Derivative Spectra of PAN Complexes The zero-order spectra of solutions of nickel (curve S), zinc (curve 2) and copper (curve 3) complexes of PAN in an aqueous ethanolic medium and of their mixture (curve 4) are shown in Fig. 1. The absorption spectra overlap considerably and, therefore, direct spectrophotometric determination of one metal in the presence of another is not possible. The second derivative spectra of the complexes are also shown in Fig. 1 (cuves 1', 2', 3' and 4'). As can be seen, the higher wavelength peaks of the derivative spectra are more significant. Derivation leads to sharper zero-order bands and gives higher signals in the resulting spectra.110 ANALYST, JANUARY 1989, VOL.114 3' A 500 550 600500 550 600 500 550 600 500 550 600 Wavelengt hin m Fig. 1. (2) Zn" and (3) CulI complexes of PAN and of (4) their mixture. (1'-4') Correspond- ing second-derivative spectra. Concentration of each ion, 1 p.p.m. Zero-order absorption spectra of (1) B I 525 550 575 600 525 550 575 600 Wavelengthinrn Fig. 2. Second-derivative spectra of mixtures of Nil1, ZnlI and Cur'. a (1) 1.0; (2) 1.5; and (3) 2.0 p.p.m. each of Ni", Zn" and Cu". ( b ) [I 4 1.0, 1.5 and 1.0; ( 5 ) 2.0, 2.0 and 1.0; (6) 0.5,2.0 and 2.0 p,p.m. of N P , Zn" and CuII, respectively The characteristics of derivative spectra, such as peak height and noise level, depend on the choice of parameters such as scan speed and integration time during recording of the spectra.The optimum parameters were chosen from results of preliminary experiments. The best results were obtained with a scale range of 0.8, an average signal of 8, a wavelength interval of 1 nm and a scan speed of 50 nm min-1. The absorption spectra shown in Fig. 1 are for mixtures of the nickel, zinc and copper complexes at a concentration of 1 p.p.m. of each ion. Fig. 2 shows the spectra obtained for mixtures containing different concentrations of each ion. The intensity of the signals at 545 (distance OA), 557 (distance OB) and 595 nm (distance OC) are directly proportional to the amounts of nickel, zinc and copper present, respectively. Analytical Determination Nickel, zinc and copper can be determined on the basis of the peak heights at 545, 557 and 595 nm, respectively.In all instances the distances between the base line and the corresponding peaks are measured; good results were obtained (Fig. 2). This method is easier to use than the peak to peak method. The metal complexes of PAN are only sparingly soluble in water so the use of a certain percentage of ethanol is necessary to prevent precipitation. A 3 + 2 ethanol - water medium was selected for all subsequent work. The absorbance of the metal - PAN complexes is affected by pH; a constant zone (ie., no variation in absorbance) is observed in acidic media. The use of an acetic acid - sodium acetate buffer (pH 4.8) is convenient. The calibration graphs obtained show a linear relationship between the distances measured and the concentrations of the metal ions in the range 0.3-2.0 p.p.m.of nickel(II), 0.5-2.5 p.p.m. of zinc(I1) and 0.5-3.0 p.p.m. of copper(I1) (Fig. 3); 50 40 E 30 i- 1 0) Q, r Y m .- a 20 10 0 I I I 0.5 1.0 1.5 2.0 2.5 3.0 Concentration, p.p.rn. Fig. 3. Second-derivative signal height vs. concentration calibration graphs for Ni", Zn" and CU" complexes of PAN. (1) Ni", 545 nm; (2) Zn", 557 nm; and (3) CuII, 595 nm Table 1. Results of the simultaneous determination of nickel, zinc and copper in their mixtures with PAN using second-derivative spectro- photometry Sample No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mass addedlpg Mass found*lpg Ni Zn c u 25.0 25.0 25.0 12.5 25.0 50.0 12.5 12.5 37.5 50.0 12.5 37.5 50.0 25.0 12.5 37.5 12.5 25.0 37.5 12.5 12.5 37.5 25.0 12.5 7.5 50.0 50.0 7.5 25.0 50.0 12.5 50.0 75.0 25.0 62.5 12.5 25.0 50.0 12.5 7.5 12.5 12.5 Ni Zn c u 24.8 24.9 25.0 12.1 25.2 49.8 12.5 12.3 37.8 50.8 12.3 37.2 52.5 25.4 12.8 37.0 12.8 25.4 37.1 12.6 13.0 37.1 25.0 12.8 8.2 52.0 49.0 7.7 25.8 51.4 12.8 51.6 72.0 25.8 60.9 11.3 25.2 49.4 12.0 7.5 11.9 12.12 * Each result is the mean of three determinations.the corresponding correlation coefficients are 0.998,0.999 and 0.985. The sensitivity of the method is 0.2, 0.3 and 0.5 p.p.m. for nickel(II), zinc(f1) and copper(II), respectively. Measure- ments on 11 solutions containing 1.0 p.p.m. of nickel, 2.0 p.p.m. of zinc and 2.0 p.p.m. of copper gave relative standard deviations of 3.7, 2.7 and 3.0%, respectively. Table 1 gives the results of the simultaneous determination of nickel, zinc and copper, carried out as described under Recommended Procedure.It can be seen that the determina- tion of these metal ions is feasible using peak to base line measurements. An interference study showed that the influence of foreign ions on the determinations was similar to that reported in the literature for normal spectrophotometry. Hence, cobalt(II), iron(II), EDTA, phosphate, cyanide and citrate interfere at concentrations greater than 1.5 p.p.m. No mutual interfer- ence between nickel, zinc and copper was observed in the concentration ranges studied.ANALYST, JANUARY 1989, VOL. 114 111 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. References Schmitt, A., Tec. Lab., 1978, 5 , 1207. Chadburn, B. P., Anal. Proc., 1982, 19, 42. O’Haver, T. C., and Green, G. L., Anal. Chem., 1976,48,312. Talsky, G., Mayring, L., and Kreuzer, H., Angew. Chem., 1978, 90, 840. Talsky, G., Gotz-Maler, S., and Betz, H., Mikrochim. Acta, 1981, 11, 1. Fell, A . F., Anal. Proc., 1978, 15, 260. Talsky, G., Znt. J. Environ. Anal. Chem., 1983, 14, 81. Cahill, J. E., and Padera, F. G., Am. Lab., 1980, 12, 101. KuS, S., and Marczenko, Z . , Analyst, 1987, 112, 1503. Ren, Y . , Lin, Z . , and Zhou, H., Fenxi Huaxue, 1985, 13, 6 . 11. 12. Kucher, A. A . , Poluektov, N. S . , Mishchenko, V. T., and Alesandrova, N. N., Zavod. Lab., 1983, 49, 11. Kvaratskheli, Y. K., Demin, Y. V., Pchelkin, V. A . , Kukush- kin, G. R., and Melchakova, N. V., Zh. Anal. Khim., 1983,38, 1434. Busev, A. I., and Kiseleva, L. V., Vestn. Mosk. Univ. Ser. Mat. Mekh. Astron. Fiz. Khirn., 1958, 13, 179. Cheng, K. L., Anal. Chem., 1955, 27, 582. Gill, H. H., Rolf, R. F., and Armstrong, G . W . , Anal. Chem., 1958, 30, 1027. Paper 8/01 031 E Received March 15th, 1988 Accepted July 19th, 1988 13. 14. 15.

ISSN:0003-2654    

DOI:10.1039/AN9891400109

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYST, JANUARY 1989, VOL. 114 113 Determination of Airborne Limonene Vapour by Charcoal Tube Sampling and Gas - Liquid Chromatographic Analysis Edward Searle Research Laboratory, London Underground Ltd., 566 Chiswick High Road, London W4 5RR, UK Keywords: Limonene; charcoal adsorbent chromatography tubes; solvent desorption; carbon disulphide; gas A procedure is described for monitoring airborne limonene vapour. The vapour is adsorbed on to charcoal, desorbed with carbon disulphide and analysed by gas - liquid chromatography. The calibration graph is linear up to 840 pg of limonene and the desorption efficiency of the solvent is 100 L 2%. 1 - Limonene occurs in some cleaning materials and natural products. It is known to be a skin irritant although no recommended exposure limits have been published.Limonene vapour has been monitored in tobacco smoke' and in a range of other materials by gas chromatography using head-space analysis,'J thermal desorption4.5 and solvent desorption from tubes filled with Tenax GC.6 In our laboratory limonene was found to decompose when in contact with hot metallic surfaces and so monitoring of the vapour was carried out using the procedure described below. The reasons for this decomposition and the nature of the decomposition products were not investigated. This paper describes a rapid and reliable method for the monitoring of airborne limonene vapour which involves adsorption of the vapour on to charcoal followed by its desorption with carbon disulphide and subsequent analysis by gas - liquid chromatography. The detection limit of this method is 5 pg and the working range is 5-840 pg oflimonene.Experimental Apparatus A Pye Unicam 304 gas chromatograph fitted with a flame ionisation detector and a Perkin-Elmer 56 chart recorder was used. The operating conditions were as follows: column, 2 m X 4 mm i.d., glass, filled with 5% OV-101 on Chromosorb G, 100-120 mesh; carrier gas, helium, flow-rate 30 ml min-1; column oven temperature, 150 "C (isothermal); injector temperature, 250 "C, and detector temperature, 250 "C. Under these conditions, the retention time of limonene was 4.4 min. The other apparatus and conditions employed were as follows. Charcoal tubes. 100 and 50 mg. Type 226-01 (SKC). Developing vibrator and vial rack. Type 22D-1B (SKC). Microsyringes, 1 and 10 pl.Air sampler. PAS 1000 fitted with a sample tube holder Sampling rate, 30 ml min-1. Sampling time limit, 8 h. Septum vials. SKC. Bubble tube, 0-10 ml. Pipette, 0.5 ml. (SKC) . Reagents D-Limonene. Analytical-reagent grade (Sigma). Carbon disulphide. Uvasol grade (Merck); used for desorp- tion of limonene from the charcoal-filled tubes. Procedures Calibration Calibration standards were prepared by injecting aliquots (0.1, 0.3, 0.5, 0.7 and 1.0 p1) of limonene directly into 0.5-ml aliquots of the desorbing solvent contained in septum vials and mixing well. The mass of limonene in each standard was calculated, assuming the density of limonene to be 0.84 g ml-1. Aliquots ( 5 p1) of each standard solution were injected into the gas chromatograph in turn and the height of the limonene peak was determined in each instance.A calibration graph of peak height versus mass of limonene was plotted. Determination of the desorption efficiency of the solvent The desorption efficiency of the solvent (CS,) was determined using the syringe-loading method.7-10 Limonene (0.5 pl) was injected directly on to the main section of an adsorbent tube, which was then broken and the main charcoal section added to a 0.5-ml aliquot of the desorbing solvent in a septum vial. The vial was vibrated for 30 niin and a 5-p1 aliquot of this solution was injected into the gas chromatograph. The height of the limonene peak was determined and compared with that of the 0.5-pl calibration standard, determined as described under Calibration. The efficiency of the desorbing solvent could thus be calculated.Analysis of samples adsorbed on the charcoal adsorbent tubes All samples were analysed as soon as possible after sampling in order to prevent migration of vapour from the front to the rear section of the charcoal tubes. No such migration of vapour was observed during this work. The front and rear charcoal sections were removed from the adsorbent tube and added to 0.5-ml aliquots of the desorbing solvent in separate septum vials. The vials were vibrated for 30 min and 5-1-11 aliquots of the solution from each section were injected in turn into the gas chromatograph. The height of the limonene peak was determined in each instance and the mass of solvent vapour adsorbed in both sections was calculated using the calibration graph, allowing for the desorption efficiency of the desorbing solvent.If the limonene vapour was found in the rear portion of charcoal, then the analysis was declared void. The concentration of limonene vapour in the original sample of air was calculated in mg m-3. Results and Discussion Range and Scope of the Method The calibration graph was linear up to 840 pg of limonene. This was the maximum mass investigated. The lower limit114 ANALYST, JANUARY 1989, VOL. 114 depended on the noise level of the detector and on the blank value of the desorbing solvent and was found to be 5 pg when a calibration graph covering the range 0-840 pg was used. The desorption efficiency of the solvent (CS2) was 100 If: 2%. When sampling was carried out at a rate of 30 ml min-1 over a full 8 h working shift there was no evidence of any breakthrough of limonene vapour into the rear charcoal section of the absorber tube at limonene vapour concentra- tions of up to 30 mg m-3.This method can be used for the analysis of limonene vapour from a wider range of materials than those investigated by the head-space or thermal desorption procedures described previously.2-6 Problems arising from thermal decomposition of the limonene vapour in the thermal desorption apparatus are also eliminated. 1. 2. 3. 4. 5 . 6. 7. 8. 9. 10. Conclusions The proposed method affords a versatile and reliable pro- cedure for the determination of limonene vapour in air. The recovery of the vapour from the charcoal adsorbent tubes was 100 k 2%. The problem of thermal decomposition of the vapour when in contact with some metals was eliminated. References Ho, C. H., Griest, W. H., and Guerin, M. R., Anal. Chem., 1976. 48, 2223. Massaldi, H. A., and King, C. J., J . Food Sci., 1974, 39, 434. Marsili, R., LCIGC, 1986, 4, 358. Lund, E. D., and Shaw, P. E., J . Assoc. Off. Anal. Chem., 1979, 62, 477. Lloyd, R. J.. J . Chromatogr.. 1984, 284, 357. Simon, P. W . , Lindsay, R. C., and Peterson, C. E., J . Agric. Food Chem., 1980, 28, 549. Krajewski, J., Gramiec, J . , and Dobecki, M., Am. Znd. Hyg. Assoc. J., 1980, 41, 531. Larkin, R. L., Crable, J . V., Catlett, L. R., and Seymour, M. J . , Am. Znd. Hyg. Assoc. J . , 1977, 38, 543. Saalwaechter, A. T., McCammon, C. S . , Roper, C. P., and Carlberg, K. S . , Am. Znd. Hyg. Assoc. J . , 1977, 38, 476. Health and Safety Executive, “Methods for the Determination of Hazardous Substances: Adsorbent Tube Standards; Prepa- ration by the Syringe-loading Technique, MDHS 33,” Health and Safety Executive, London, 1983. Paper 8/01 983 E Received May 19th, 1988 Accepted August 4th, 1988

ISSN:0003-2654    

DOI:10.1039/AN9891400113

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYST, JANUARY 1989, VOL. 114 115 COMMUNICATION Material for publication as a Communication 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 receive priority and are usually published within 5-8 weeks of receipt. They are 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. Manuscripts are usually examined by one referee and inclusion of a Communication is at the Editor’s discretion. Effect of Microwave Drying on the Results of Subsequent Analytical Tests Howard K. Worner and Nicholas Standish Microwave Applications Research Centre, The University of Wollongong, New South Wales, Australia Keywords: Microwave drying; analytical samples; results difference Many standard tests for determining the chemical and physical properties of powders and porous solids specify that the samples must be oven dried before being subjected to these tests.Generally, standards specifications do not state the type of drying oven to be used but state simply that the drying is to be carried out in a “laboratory drying oven.” In recent years many laboratories have installed microwave ovens, generally of the domestic variety, for drying test samples. Because microwave drying is very rapid it saves time and increases throughput. Also, the cost of a microwave oven is nowadays generally much lower than that of a conventional laboratory drying oven, hence the use of microwave ovens for laboratory drying purposes will almost certainly increase.The question is “Does microwave drying change the sample in any way that might affect the property subsequently being tested ‘? ’* It is known that microwave irradiation of minerals can change their behaviour in subsequent processing1.2 and in the synthesis of new compounds. 3 In our Microwave Applications Research Centre we have successfully carried out microwave syntheses not only of the superconducting ceramics, recently reported by Baghurst et al. , A but also of a variety of other solid compounds. Further, we have demonstrated that hematite can be converted rapidly to magnetite, i.e., with a loss of 11% oxygen.at temperatures seemingly below dull red heat ( 6 5 0 “C) in the presence of a small amount of active carbon, and that titanium dioxide can rapidly lose up to 30% of its oxygen without any reductant being present. Hence these findings, together with those involving gaseous products,5 demonstrate that microwave irradiation can alter the chemical and physical nature of materials. The purpose of this communication is to draw attention to other such effects of microwave irradiation and to give a specific example of how iron ore sinter samples, “oven dried” in conventional and microwave ovens, can give different “standard” reducibility values. We have recently studied the mechanism of pore formation and the influence of pore size on the reducibility of Fe203 - CaCO? composites.As reported elsewhere,6 the materials were mixed in specified proportions and then pressed into tablets with a die. After drying, raw samples were fired in a muffle furnace and the sintered samples were then subjected to standard reduction tests at 900 “C in the presence of pure co. For convenience, drying was carried out in a domestic type 2450 MHz microwave oven operating at a power level of 500 W. For comparison, several samples were dried in a conventional laboratory drying oven and then fired and reduced as described above. As the results of the reduction tests showed some difference, a controlled study was carried out to ascertain whether the diffcrence was real and reprodu- cible. It was found that, although small in relative terms, the difference was real and reproducible.Results for the reduc- tion of samples dried in the microwave oven for various times and with all other conditions kept constant can be expressed in terms of reduction degree (RD). It was found that for drying times of 2 , 6 and 10 min, the RDs were 73.1,75.4 and 74.970, respectively. The RD for the conventionally dried samples was 74.770, These results show a maximum value for RD after microwave drying for 6 min and a difference of 0.2-1.6%, in absolute terms, from conventional drying. We have observed these maxima effects for microwave irradiation in several other systems but as yet we are unable to explain this effect with any degree of certainty. However, we can confirm that the extent of this effect appears to be related to the permittivity of the material in the microwaved sample.With regard to the difference in RD, viz., 0.2-1.6%, this may appear to be small; however, it is not when it is considered that, for example, a difference in the RD of 1% in an iron blast furnace may be equivalent to a saving of coke of up to about 10 kg per tonne 6f iron. More significantly, any differences in the general case of iron ore sinters (and of other materials) tested for compliance with the standard specifica- tion may result in costly rejections. But what if the difference is due only to the method of drying used? May not then the manufacturerlcustomer be penalised wrongly? We believe that the questions we have raised are sufficiently important to merit a follow up by the scientific community in general, and by those involved in the standardisation of specifications and the methods of testing and analysis.116 References 1. 2. 3. Chen, T. T., Dutrizac, J. E., Haque, K. E., Wyslovzil, W., and Kashyap, S . , Can. Metall. Q., 1984, 23, 349. McGill, S . L., and Walkiewicz, J . W., J . Microwuve Power, 1987, 22, 175. Baghurst, D. R . , and Mingos, D. M. P., J . Chem. SOC., Chem. Commun., 1988, 829. ANALYST, JANUARY 1989, VOL. 114 4. 5 . 6. Baghurst, D. R., Chippindale, A. M., and Mingos, D. M. P., Nature, 1988, 332, 311. Wall, E. T., J . Microwave Power, 1983, 18, 31. Standish, N., and Yang, Y. H., J. Muter. Sci. Lett., 1988, 7, 524. Paper 8104495C Received November 11 th, 1988

ISSN:0003-2654    

DOI:10.1039/AN9891400115

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYST, JANUARY 1989, VOL. 114 117 BOOK REVIEWS Kinetic Aspects of Analytical Chemistry Horacio A. Mottola. Chemical Analysis, Volume 96. Pp. xvi + 285. Wiley. 1988. Price f62.50. ISBN 0 471 83676 1. The release of this monograph is timely: on the one hand, one should consider the growing acknowledgement of the role played by kinetics in the context of analytical chemistry; on the other, one should admit the existence of a “black hole” in the literature on this topic. The last two books on this subject were published more than 20 years ago and were essentially concerned with reaction-rate methods. These comprise only a part of kinetic methods and are based on measurements carried out under non-equilibrium physical and chemical conditions. All this is properly dealt with in the~first chapter of Mottola’s book, which offers a historical perspective of the attitude of analytical chemists towards kinetics.Chapters 2-4 deal with solution catalytic methods, namely enzymatic, non-enzymatic and modified methods, and outline their basic principles and applications. Chapter 5 is an interesting approach to electrode reactions and immobilised enzymes, interrelated via heterogeneous catalysis, of doubt- less educational and practical interest. Two more chapters (6 and 7) whose contents (use of uncatalysed reactions and differential methods) are essential in the context of reaction- rate methods make up the first part of the book. Chapters 9 and 10, concerned with instrumentation and errors inherent in kinetic-based determinations, should ideally have followed the first seven.Chapters 8 (kinetic methods based on detection of light emission) and 9 (kinetic components in various analytical techniques or steps in analysis) justify the title of the book. Their contents, though, should have been expanded to offer a more comprehensive view of the subject; nevertheless, they provide the reader with an overview of the role of kinetics in analytical chemistry. By no means did the author try to gather all the literature references available on all the subjects dealt with; instead he made a personal selection of the references, some of which will inevitably have been missed. The author’s acknowledged contribution to kinetics in analytical chemistry in the last 20 years as a prolific author of reviews and a promoter of international symposia on this topic has culminated in the publication of this book, which masterfully reflects the impact of kinetics on analytical methods. The book will be of use to analytical chemistry teachers and researchers alike. M .Vulcurcel Flow Injection Analysis. Second Edition Jaromir ReiiEka and Elo Harald Hansen. Chemical Analy- sis, Volume 62. Pp. xxii + 498. Wiley. 1988. Price f65. ISBN 0 471 81355 9. The economic and practical affordability of flow injection analysis, together with its great versatility, have accelerated the spectacular growth of this technique in the present decade. Therefore, it is not surprising that this second edition is not only a generous extension of the first (1981), but also deals appropriately with new approaches to FIA.In contrast to the first edition, the authors have been somewhat more receptive to the contributions from other teams outside their sphere of influence. The material could probably have been better organised. The first three chapters, devoted to the fundamentals of automation in analytical chemistry, FIA principles and foundation, respectively, are well suited to the state of the art of this topic. The description of the components of an FIA system (Chapter 5 ) should have preceded that of FIA techniques (Chapter 4). The latter should have been split into two or three chapters owing to the enormous variety of techniques described so far. Chapter 6, which offers a detailed explanation of some practical exercises, is superfluous on account of the current degree of consolidation of FIA.On the other hand, one misses one or several chapters concerned with the resolution of analytical problems in areas such as environmental, clinical and pharmaceutical chemistry. Chapter 7, dealing with FIA literature, features a dual, contrasting approach: in the first part, the authors give their own view of the topic; in the second, they offer an orderly compilation of FIA references, of use to those interested in the topic. The last chapter, devoted to FIA trends, is of some interest. The authors’ experience in the topic covered and their ease of communication are clearly reflected in this second, care- fully presented edition. The book is readable and will be of use both to FIA specialists and to scientists and technicians interested in this alternative, a valuable and widely applicable interface between samples and analytical instruments. M.Vulcarcel Biof lavou r ‘87. Analysis, Biochemistry, Biotech nolog y. Proceedings of the International Conference, Wurzburg, Federal Republic of Germany, September 29-30, 1987 Edited by Peter Schreier. Pp. xii + 584. Walter de Gruyter. 1988. Price DM318. ISBN 3 1 1 01 1204 3. The book contains 37 papers that were presented at the Bioflavour Symposium held in Wurzburg in 1987. According to the Editor, the aim of the symposium was to review aspects of natural flavours, stimulate new ideas and interest between disciplines and to bring about a cross-fertilisation of the different approaches. It was also hoped that it would provide workers in specialised fields with an opportunity to see their work in a broader perspective and to discuss the relevance and limitations of various approaches and finally, and probably most important, to bring together the views of both academic and industrial workers.The term “bioflavour,” coined to mean naturally produced flavours, is reviewed in the first contribution. Flavours produced by biotechnological processes have the advantage that they possess the legal status of a natural compound, they have a defined stereochemistry, they are produced under mild conditions and they are free from pest infestation and ecological disasters. Under the heading Analytical Techniques, five contribu- tions concern the separation of chiral compounds and the remaining six deal with methods of analysis using gas chromatography - mass spectrometry or the identification of flavour compounds in fruit and vegetables. A further section deals with the biochemical formation of flavour compounds or their precursors.Tissue culture is the subject of a further six papers and another seven contributions are concerned with the microbiological aspects of flavour compounds. The final group of papers concern the use of enzymes for the formation of volatile flavour compounds.‘ A glance at the names and addresses of the organisations who have sponsored the work described in this book shows that almost all are either universities or government institutes. It is unfortunate, although perhaps understandable, that no flavour houses or companies dealing with the production of new flavours for industry were represented at this meeting.The scientific content of the contributions reflects the type of work that would be expected to emanate from academic institutions and, in this respect, it must be said that one of the118 ANALYST, JANUARY 1989, VOL. 114 aims, that of bringing together the views of both academic and industrial workers, has seemingly failed. Workers who are actively involved in flavour research who did not attend the meeting may well find the book useful additional reading. Commercially minded research managers will have to look long and hard to find any results that would radically change their research programme. The book is well presented, although each chapter has a different typeface owing to the wide range of typewriters and printers that were used by each individual organisation to prepare their papers.Probably owing to the speed at which the contributions were required for publication, a large number of misprints and spelling mistakes are present. Michael J . Saxby Pulse Methods in I D and 2D Liquid-Phase NMR Edited by Wallace S. Brey. Pp. x + 561. Academic Press. 1988. Price $90. ISBN 0 12 133155 5. This book has been written to help the practising NMR spectroscopist to gain some insight into the various new techniques now possible and to gauge the utility of a particular method according to the instrumentation available to him or her. The authors of each chapter are world authorities in NMR, in both research and teaching, and the approach is a mix between schoolmasterly and review.Indeed, the early chap- ters include some exercises to assist the reader in grasping the basic principles of the subject. Throughout the book, theory and practice are discussed, and mostly the subject matter is given both simple and detailed treatment. A fair proportion of the book is mathematical, but the text is always easy to read and well illustrated with clear diagrams. The contents are as follows. 1. Basic Methods and Simple Pulsed Experiments, by Wallace S. Brey. 2. Density-Operator Theory of Pulses and Precession, by Malcolm H. Levitt. The book begins with two foundation chapters and reference is frequently made to these in later sections of the book. 3. Polarization Transfer and Editing Techniques, by Ole W. Sarensen and Hans J.Jakobsen. Chapter 3 is very well organised and takes the reader from polarisation transfer and purging, for removal of undesirable resonances, through to heteronuclear spectral editing techniques. A useful compari- son is made between editing techniques utilising polarisation transfer and those employing nuclear Overhauser enhance- ment to increase sensitivity. 4. Principles of Multiple-Quantum Spectroscopy, by Thomas H. Mareci. The principles of multiple-quantum spectroscopy are introduced and illustrated with examples of application to both small simple molecules and large complex biomolecules. 5 . Application of Two-Dimensional NMR Experiments in Liquids, by George A. Gray. This chapter illustrates extremely well the various 2D NMR experiments available and discusses the merits and problems associated with each.Practical suggestions are given to assist the experimenter. The applications reviewed range from J-resolved, through chem- ical shift correlation (including relayed coherence transfer) and magnetisation transfer, to zero- and multiple-quantum 2D methods. 6. Application of 2D NMR to Biological Systems, by J. H. Prestegard. Application of 2D NMR methods to the analysis of bio-macromolecules is illustrated for protein, nucleic acid and carbohydrate structures. To overcome problems of spectral resolution in such systems, details of spectrum acquisition and appropriate processing and display parameters are considered. The special problem of elimin- ating the water resonance in protonated media is also addressed. 7.Multiple-Resonance and Two-Dimensional NMR Tech- niques in Analysis of Fluorocarbon Compounds and Poly- mers, by Derick W. Ovenall and Raymond C. Ferguson. This short chapter illustrates the use of multiple-resonance and 2D techniques in 19F NMR and very clearly demonstrates the potential for assigning stereo sequences in fluoropolymers. 8. Recent Developments in Pulsed NMR Methods, by Wallace S. Brey. The concluding chapter reviews recent developments and improvements in pulsed NMR, some of which relate directly to discussions in earlier chapters. Topics covered include RELAY methods involving different co- herence pathways, homonuclear correlation (filtered COSY), isotropic mixing (total coherence transfer and homonuclear Hartman - Hahn) , application of zero-quantum coherence and improved design of 2D nuclear Overhauser enhancement procedures.For the practising NMR spectroscopist, this book provides a valuable overview of the considerable advances currently being made in this field and it will be an important addition to the laboratory book-shelf and technical library alike. A . A . S. Bright ~ Quantitative Gas Chromatography for Laboratory Analy- ses and On-line Process Control George Guiochon and Claude L. Guillemin. Journal of Chromatography Library, Volume 42. Pp. xii + 797. Elsevier. 1988. Price Dfi 315; $165.75. ISBN 0444 428577 (Volume 42); 0 444 41616 1 (Series). The reviewer might be forgiven perhaps for echoing the comment of a contemporary in the world of music who wrote, “Ye gods! Not another LP by Oscar Peterson!,” but these eminent authors pre-empt our writing, “Not another tome about gas chromatography!,” by making the point in the Introduction that this is now a mature and firmly established science to which the number of really new contributions is in decline; they feel the time has come for an up-to-date volume which (to use their phrase) is “reasonably complete.” [They quote also from Mark Twain (“The Adventures of Huckleberry Finn,” Chapter XLIII): “.. . and so there ain’t nothing more to write about, and I am rotten glad of it, because if I’d knowed what trouble it was to make a book I wouldn’t a tackled it and I ain’t going to no more.”] No doubt many authors would echo such sentiments. In this instance the book that has been made consists of 793 pages, 17 chapters, a lexicon of chromatography, nearly 1300 references and a subject index.The entire undertaking is well planned and in addition to the opening clear statement of “Contents” there is at the commencement of each chapter a detailed outline of what it contains. The literature cited is given at the end of each chapter. The text following the Introduction includes fundamentals of the chromatographic process (covering the flow of gases through chromatographic columns, thermodynamics of reten- tion, band broadening and the overloading of columns); the optimisation of experimental conditions; advanced packed columns; open-tubular columns; instrumentation; detectors; retention data; “hyphenated” techniques (GC - MS, GC - IR); measurement of sample size; response factors; measure- ment of peak area and derivation of sample composition; sources of errors; and applications to analysis for purposes of process control.(Most chapters include also a glossary of the terms used, which makes a further useful contribution to the clarity of the text.)ANALYST, JANUARY 1989, VOL. 114 119 The title notwithstanding, both “quantitative” and qualita- tive gas chromatography are covered; fundamentals are reviewed more than adequately and the sections on method- ology do not seem to have overlooked much of significance. Under “hyphenated” techniques, the coupling of mass spectrometry or infrared spectroscopy (including FTIR) with gas chromatography are all described to a sufficient extent. The types of detector of which details are given include gas density balance, thermal conductivity, flame-ionisation, elec- tron-capture, thermionic, flame photometric, photoionisation and helium ionisation.The chapter on applications to the control of processes gives details of on-line equipment and examples of its uses, such as the analysis of hydrogen in catalytic reforming, the synthesis of vinyl chloride, the analysis of gases evolved during chloration, the analysis of gaseous ammonia, the synthesis of phthalic anhydride, the analysis of recycled styrene, the analysis for airborne contamination in a polymerisation unit, the analysis of chloral and the control of a dichlorodifluoro- methane unit. Doubtless the control of processes such as these will be one of the fields of future development; in this chapter at least the reviewer felt that there was not the same sense of being “reasonably complete” as was given elsewhere in the book.However, as a whole it is a splendid volume, which must have required of the authors an extraordinary amount of time and care. They have succeeded in their purpose and any student of gas chromatography is recommended to buy this book if possible, or at least to borrow it from the research or industrial libraries astute enough to include it among their acquisitions. D. Simpson Interpretation of Carbon-13 NMR Spectra. Second Edition F. W. Wehrli, A. P. Marchand and S. Wehrli. Pp. xii + 484. Wiley. 1988, Price €37.50. ISBN 0 471 91742 7. This new edition is over 50% longer than the first, reflecting the significant changes in NMR that have taken place over the last 10 years.The book itself is well printed, with the exception of a few spectral figures that have not reproduced clearly. It comes in a bright blue laminated hardback cover, which is not sturdy enough for the service it will see. Many readers will notice that the new edition lacks the very useful fold-out carbon NMR chemical shift correlation table that was a feature of the first edition. Like the first edition, this book is aimed at readers who wish to exploit carbon-13 NMR as a structural characterisation tool. It covers the field of solution NMR, with brief excursions into both solids and NMR in vivo. The layout of the new edition remains the same, five chapters which are clearly summarised in the Contents list. This makes for easy use as a reference book.Chapter 1 deals with the basic principles of 13C NMR in a readable manner and with the minimum of mathematics. Instrumental advances, in particular the advent of super- conducting magnets which have revolutionised the acquisition of NMR data, are reviewed. Chapter 2 is little changed and examines spectral parameters. Chapter 3 has been greatly expanded to reflect the profusion of new experimental techniques for spectral assignment. Advances in hardware and software have led in particular to the 2D technique, which in many instances allows the complete assignment of an un- known molecule without recourse to other structural informa- tion. This chapter also introduces the technique of 13C solid-state NMR-a technique still in its infancy with few specialised commercial instruments available. It does hold great promise for eliciting information on, for example, polymers that are “insoluble” and not amenable to solution- state NMR. Chapter 4 concerns nuclear spin relaxation. Chapter 5 covers the application of carbon-13 NMR to the solution of structural chemistry problems. It includes stepwise systematic approaches to various problem solutions. It also includes problems (and solutions) for the reader to tackle. Overall the coverage of the book is good, although a fuller treatment of DEPT would have reflected the common use of this technique in the modern laboratory. This is a good book for the chemist and a useful reference for the practical NMR spectroscopist. R. A . Hearmon M . P. Rhodes

ISSN:0003-2654    

DOI:10.1039/AN9891400117

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

120 ANALYST, JANUARY 1989, VOL. 114 Arias, Juan J., 93 Barker, Ian K., 41 Bartle, Keith D., 41 Beh, S . K . , 29 Berridge, John C., 53 Bianchi, Alexander, 47 Brown, R. Stephen, 33 Cano Pavon, J . M., 109 Chakraborty, Debasis, 67 Clifford, Anthony A., 41 Dabrowski, Konrad , 83 Das, Arabinda K., 67 Das, Sukomal, 101 de la Guardia Cirugeda, M., 77 Deorkar, Nandkurnar V., 105 CUMULATIVE AUTHOR INDEX JANUARY 1989 Din, Aftab, 57 Dumkiewicz, Ryszard, 21 Efstathiou, Constantinos E., 25 Evans, William H., 71 Fell, Anthony F., 53 Gallardo CCspedes, A., 109 Gallardo Melgarejo, A., 109 G6rnez-Hens, Agustina, 89 GutiCrrez, M. Carmen, 89 Halford-Maw, Peter A., 41 Hinterleitner, Silvia, 83 Holcombe, James A., 4 1 Houlgate, Peter F , 71 JimCnez, Ana I., 93 Jimhez, Francisco, 93 Khopkar, Shripad M., 105 Kithinji, Jacob P., 41 Koilpillai, Robinson N., 33 Krull, Ulrich J., 33 Leyon, Robert E., 61 Midgley, Derek, 1 Moody, G. J., 15, 29 Nespolo, Roberto, 33 PCrez-Bendito, Dolores, 89 Psaroudakis, Stavros V., 25 Ragheb, Hussein S . , 57 Raynor, Mark W., 41 Ridge, Steven, 57 Rodilla Soriano, F., 77 Saad, Bahruddin B., 15 Safarzadeh-Arniri, Ali, 33 Searle, Edward, 113 Sethi, P. D. , 101 Shao, Ji-Xin, 97 Sharma, Suresh C., 101 Shilstone, Gavin F., 41 Standish, Nicholas, 115 Talwar, Santosh K., 101 Thomas, J. D. R., 15, 29 Vandenberg, Elaine T., 33 Varney, Mark S . , 47 Worner, Howard K., 115 Wright, Adrian G., 53 Zhu, Yu-Lun, 97

ISSN:0003-2654    

DOI:10.1039/AN9891400120

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYST, JANUARY 1989, VOL. 114 121 INSTRUCTIONS TO AUTHORS The Analyst publishes papers on all aspects of the theory and practice of analytical chemistry, fundamental and applied, inorganic and organic, including chemical, physical, biochem- ical, clinical, pharmaceutical, biological, automatic and com- puter-based methods. Papers on new approaches to existing methods, new techniques and instrumentation, detectors and sensors, and new areas of application with due attention to overcoming limitations and to underlying principles are all equally welcome. 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. Full papers, describing original work.Short papers: the criteria regarding originality are the same as for full papers, but short papers generally report less extensive investigations or are of limited breadth of subject matter. 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 receive priority and are usually published within 5-8 weeks of receipt. They are 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. Communications will normally be examined by one referee.Reviews, which must be a critical evaluation of the existing state of knowledge on a particular facet of analytical chem- istry. 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 photographs) 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.Regional Advisory Editors. 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. 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Up to 5 keywords or key phrases, indicating the topics of importance in the work described, should be included after the synopsis. ( d ) 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.(e) 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. (f, Results. These are best presented in tabular form, followed by any statistical evaluation, which should be in accordance with accepted practice. (8) Discussion ofresults. 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 used.Common trivial names may be used, but should first be defined in terms of IUPAC nomenclature. SI units. 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 ( b ) temperatures should be expressed in K or "C (not OF); ( c ) wavelengths should be expressed in nanometres (nm) ( 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; in mass spectrometry, signal intensity should be expressed in counts s-1 and not in Hz; in millimetres (mm); (not mp);122 ANALYST, JANUARY 1989, VOL. 114 ( e ) radionuclide activity will be expressed in becquerels (Bq) or curies (Ci); 1 Ci = 3.7 x 1010 Bq; (f, the micron (p) will not be used; 10-6 m will be 1 ym.Abbreviations. SI units should be used. Molarity is generally expressed as a decimal fraction (e.g., 0.375 M). Abbreviational full stops are omitted after the common contractions of metric units (e.g., ml, g, pg, mm) and other units represented by symbols. Abbreviations other than those of recognised units should be avoided in the text. 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 “w” for weight and “v” for volume. The following show the manner of expressing these percentages together with an acceptable alternative given in parentheses: YO 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. 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 should be brief.Tables consisting of only two columns can often be arranged horizontally. Tables must be supplied with titles and be so set out as to be understandable without reference to the text. Either tables or graphs may be used but not both for the same set of results, unless important additional information is given by so doing. The information given by a straight-line calibration 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 represent numerical values, is, for example: Volume/ml. The diagonal line (solidus) will not be used to represent “per”. In accordance with the SI system, units such as grams per millilitre are already expressed in the form g ml-1.For a table (or graph), this would appear as: Concentration of solution/g ml-1. It should be noted that the “combined” unit, g ml-1, must not have any “intrusive” numbers. To express concentration in grams per 100 milli- litres, the word “per” will still be required: Concentrationlg per 100 ml. It may be preferable for an author to express concentrations in grams per litre (g 1-1) 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 artwork 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 lettering 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., Foote and Delves,1 Burns et al.2 or Hirozawa,3 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. Foote, J. W., and Delves, H. T., Analyst, 1983, 108, 492. 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 Chemistry, Part II,” Volume 14, Wiley, New York, 1971, p. 23. Journal titles should be abbreviated according to the Chemical Abstracts Service Source Index (CASSI) .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; second-hand references are a frequent source of error. The number of references must be kept to a minimum. 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 Symbol for unit m kg S A K mol cdANALYST, JANUARY 1989, VOL. 114 123 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 quantity energy force power electric charge electric potential difference electric resistance electric capacitance frequency magnetic flux density radionuclide activity (magnetic induction) Examples of other derived SI units are- Physical quantity area volume density velocity angular velocity acceleration magnetic field strength Name of unit joule newton watt coulomb volt ohm farad hertz tesla Symbol for unit J N W C V Q F Hz T kgs-2A-1 = Vsm-2 becquerel Bq S-' SI unit square metre cubic metre kilogram per cubic metre metre per second radian per second metre per second squared ampere per metre Certain units will be allowed in conjunction with the SI system, e.g.- Physical Name Symbol quantity of unit for unit volume litre 1 magnetic flux density (magnetic induction) gauss G temperature, t degree Celsius "C radionuclide activity curie Ci energy electronvolt eV Symbol for unit m2 m3 kg m-3 m s-1 rad s-1 m s-2 A m-1 Definition of unit lO-3m3 = dm3 10-4 T tl"C = TIK - 273.16 3.7 X 1010Bq 1.6021 x 10-19 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)- 10-3 milli m 10-9 nano n 10-6 micro c1 10-12 pic0 P Compound prefixes (e.g., mkm) should not be used; 10-9 m = 1 nm. 103 kilo k 106 mega M 109 gigs G 10'2 tera T 1015 peta P 1018 exa E The Royal Society of Chemistry, Burlington House, Piccadilly, London Wl V OBN, UK

ISSN:0003-2654    

DOI:10.1039/AN9891400121

出版商:RSC    

年代:1989

数据来源: RSC