ISSN:0003-2654    

DOI:10.1039/AN96186FX001

出版商:RSC    

年代:1961

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN96186BX003

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

12 PARKE : THE DETERMINATION OF The Determination of 2,4=Diaminophenol [Vol. 86 and its Salts BY D. V. PARKE (Biochemistry Department, St. Mary’s Hospital Medical School, London, W.2) A method is described for the accurate quantitative determination of 2,4-diaminophenol and its salts (Amid.01). The method is based on the oxidation of 2,4-diaminophenol by potassium persulphate to the red- coloured 2-amino-4-quinoneimine, which is then determined spectrophoto- metrically from its absorption at 500 mp The oxidation is dependent on pH and is best carried out a t pH 4.5, a t which the colour is most stable. The method is sensitive to 10 pg of diaminophenol, and amines and aminophenols do not greatly interfere. With little reduction in accuracy the method has been applied to the determination of conjugates of diaminophenol in urine.~,~-DIAMINOPHENOL is best known as its dihydrochloride (Amidol), which is widely used as a photographic developer and as a dye for fur and hair. Two methods have been described for determining 2,4-diaminophenol. The first1 :is based on the conversion of diaminophenol into a mixture of the di- and tri-benzoyl derivatives, which is then determined gravimetrically. The second is based on the light absorption of the azo dyes formed by diazotisation of the diaminophenol and coupling with resorcino12 or 4-n-hexylresorcinol.3 The first method is empirical because of the variable mixture of products of the benzoylation, is non-specific and is limited to amounts of 100mg or more. The second method, although sensitive toJanuary, 19611 2,4-DIAMINOPHENOL AXD ITS SALTS 13 10 pg of diaminophenol, lacks specificity, since other ortho-aminophenols, and to a lesser extent other amines, interfere.2,4-Diaminophenol is formed biologically by the reduction of 2,4-dinitrophenol by rabbits4 and in rat-liver homogenates5 and is the principal metabolite of m-dinitrobenzene in the rabbit.6 The work described was undertaken to devise a method for determining 2,4-diamino- phenol and its conjugates in the urines of animals dosed with m-dinitrobenzene, 2,4-dinitro- phenol and other compounds metabolised to the diaminophenol. It was particularly desirable to develop a method in which m-nitroaniline, m-phenylenediamine and aminonitrophenols would not interfere. The colorimetric methods previously described2s3 give strong colours with the aminonitrophenols, and the colours with 2-amin0-4-nitropheno1, another major metabolite of m-dinitrobenzene, are even more intense than those given by 2,4-diamino- phenol.Moreover, 2,4-diaminophenol gives “muddy” colours in these methods, due probably to the formation of insoluble brown oxidation products. DEVELOPMENT OF THE METHOD The great facility with which 2,4-diaminophenol and its salts are oxidised atmospherically invalidated several of the possible methods investigated; ultimately, this facile oxidation was made the basis of a method. Solutions of 2,4-diaminophenol and its salts darken on exposure to air and ultimately form an insoluble brown polymeric oxidation product. In contrast to this, if the solutions are oxidised by the addition of aqueous ferric chloride, potassium dichro- mate or bromine water, a deep red colour is produced owing to the formation of salts of 2-amino-4-quinoneimine.7 98 The oxidant chosen for the proposed method was potassium persulphate, since it is as effective as the oxidants used by previous workers and has the advantage of being colourless.A considerable excess of potassium persulphate was needed to ensure rapid development of the colour, and at pH values of 4 to 7 a final concentration of 200 ,ug per ml was found to be optimal for final concentrations of diaminophenol dihydrochloride up to 50 pg per ml. The amount of persulphate did not affect the colour intensity, but at concentrations of less than 200 pg per ml a longer time was necessary for maximum colour development.The salts of 2-amino-4-quinoneimine are holoquinoid and exhibit a general light absorption in the violet region.8 The spectral absorption curve for a solution of 2,4-diaminophenol dihydrochloride oxidised with potassium persulphate showed this general absorption, which was maximal at 480 to 500mp; 500mp was chosen as the wavelength in the proposed procedure. EFFECT OF pH- Below pH 0 no colour develops, above pH 0 the rate of colour development increases with rise in pH and in neutral solutions it is almost instantaneous. Above pH 7 the red colour is immediately formed, but quickly fades to brown. Even between pH 5 and 7 the red colour begins to fade slightly after 15 to 30 minutes. The variation in optical density with pH and development time is shown in Table I.At pH 4.5 the colour is stable, showing no deterioration after 1 hour, and the time for maximal colour development (10 minutes) is convenient. The development of the red colour is dependent on pH. METHOD REAGENTS- 2,4-Diamino$henol dihydrochloride-Purify by boiling a solution of 50 g of diaminophenol dihydrochloride in 150 ml of ’0.2 N hydrochloric acid with 2 g of charcoal, filter, and pre- cipitate by adding 25ml of concentrated hydrochloric acid. Collect the precipitate on a filter-paper, and dry in zlacuo over anhydrous potassium carbonate. Solutions in 0.5 N hydro- chloric acid are stable for several hours. Potassium persulphate solivtion, 0.2 per cent. wlv, aqueous-Prepare from analytical- reagent grade material.Sodium acetate solution, molar, aqueous. Prepare from analytical-reagent grade material. PROCEDURE- To 2.0 ml of a solution of 2,kdiaminophenol dihydrochloride in 0.5 N hydrochloric acid 10 to 250 pug per ml) add 1.0 ml of potassium persulphate solution and 2.0 ml of sodium14 PARKE THE DETERMINATION OF [Vol. 86 acetate solution. After 10 minutes, dilute with water to 10.0m1, and measure the optical density at 500 mp against water in l-cm glass cells. TABLES I OPTICAL DENSITIES OF SOLUTIONS OF 2,4-DIAMINOPHENOL OXIDISED WITH POTASSIUM PERSU LPHATE Two-millilitre portions of a 0-0005 M aqueous solution of 2,4-diaminophenol dihydrochloride in the presence of 6 ml of 0.2 M Britton and Robinson’s buffer solution at different pH values were treated with 1.0ml of a 0.2 per cent.w/v aqueous solution of potassium persulphate, diluted to 10.0 ml, and the optical densities measured at 500 mp against water in l-cm glass cells Development time, minutes 2 5 10 15 20 30 60 7 2.0 0.03 0.05 0.06 0.08 0.10 0.12 - 3.0 4.0 0.07 0.11 0-14 0-20 0.19 0.28 0.26 0.36 0.34 0.41 0.37 0.41 - 0-41 Opticali density at pH- A -7 4.5 5-0 6-0 7.0 8.0 9.0 0.18 0.22 0.35 0.37 0.24 0.18 0.31 0.36 0.40 0.37 0.23 0.16 0-40 0-41 0.39 0.37 0.22 0.16 0-41 0.41 0.38 0.36 0.22 0.15 0.41 0.40 0.38 0.36 0.21 0.15 0-41 0.39 0.37 0.36 0-21 0.15 - - - 0.41 0.38 - REsurrs Beer’s law was always strictly obeyed over the range 0 to 250 pg of 2,4-diaminophenol dihydrochloride per ml of solution, and 2.0 ml of a solution containing 100 pg per ml treated as described under “Procedure” gave an optical density of 0.41.Recoveries of 5 to 10oO mg of 2,4-diamino- phenol dihydrochloride from aqueous solutions were 100 The method is sensitive to 10 pg of 2,4-diaminophenol, and other related amines and phenols do not appreciably interfere (see Table 11). All results were obtained with a Unicam SP600 spectrophotometer. 2 per cent. TABLE I1 OPTICAL DENSITIES OF SOLUTIONS OF SOME AMINESS AND PHENOLS OXIDISED WITH POTASSIUM Two-millilitre portions of 0.0005 M aqueous solutions of various amines and phenols in 0.5 N hydrochloric acid were oxidised with potassium persulphate by the proposed procedure PERSULPHATE Amine or phenol Optical density Phenol . . . . . . . . . . . . 0.00 o- Aminophenol .. . . . . .. 0.05 p - Aminophenol . . . . .. . . 0.02 2-Amino-4-nitrophenol . . . . . . 0.01 4-Amino-2-nitrophenol . . . . . . 0-02 m-Phenylenediamine . . . . . . . . 0.06 2,4-Diaminophenol dihydrochloride . . .. 0.40 APPLICATION OF THE METHOD TO URINE The 2,kdiaminophenol excreted by animals as a metabolite of 2,4-dinitrophenol and other compounds occurs in the urine as conjugates of acetic, sulphuric and glucuronic acids, which are hydrolysed to diaminophenol by boiling under reflux for 3 hours with 5 N hydro- chloric acid. Recoveries of diaminophenol dihydrochloride (50 to 100 mg) boiled under reflux for 3 hours with 50 ml of 5 N hydrochloric acid and diluted ten-fold before the determination were 100 2 2 per cent. Similar recoveries were obtained with normal rabbit urine in place of pure aqueous solutions.Diaminophenol dihydrochloride (50 to 100 mg) was boiled under reflux for 3 hours with a mixture of 50 ml of urine from normal rabbits and 50 ml of concen- trated hydrochloric acid. The hydrolysed solution was cooled, diluted ten-fold, and filtered to remove a black precipitate arising from the action of the acid on glucuronides and other normal constituents of urine. Determinations b y the proposed procedure gave recoveriesJanuary, 19611 2,4-DIAMINOPHENOL AND ITS SALTS 15 of 101 The blank solution was prepared by adding 2 ml of 2 N hydrochloric acid to 2.0 ml of the filtered diluted urine solution and diluting to 10.0 ml. The effects of other metabolites of 2,4-dinitrophenol occurring in the urine in addition to 2,4-diaminophenol were studied. By the same procedure as used for normal rabbit urine, the mean recoveries of diaminophenol dihydrochloride (100 mg) added to urine in the presence of m-phenylenediamine, m-nitroaniline, 2-amino-4-nitrophenol or D-glucuronolactone (100 mg of each) were 111, 90, 93 and 102 per cent., respectively (see Table 111).3 per cent. (see Table 111). TABLE I11 RECOVERY OF 2,4-DIAMINOPHENOL FROM URINE I N THE PRESENCE OF OTHER METABOLITES OF WZ-DINITROBENZENE Amount of Diaminophenol Diaminophenol metabolite dihydrochloride Optical dihydrochloride Metabolite added added, added, density found, mg mg mg 106.4 0-45 109-8 49.7 0.20 48.8 53.2 0.22 53.7 . . 100 107.9 0.45 109.8 93.5 0.39 95.1 102.0 0.39 95.1 102.3 0*40* 97.6 107.9 0.40 97-6 . . 100 103.2 0.38 92.7 107.8 0*39* 95.1 109.1 0-49 119.5 114-6 103.3 0.47 93.5 0-44* 107.3 - 1 0.48* 117-1 1 106.2 None .. . . . . . . D-Glucuronolactone 2-Amino-4-nitrophenol . . 100 m-Xitroaniline . . In-Phenylenediamine . . 100 * Solution adjusted to pH 1.0 after formation of the colour. Recovery, % 103 98 101 102 102 93 95 90 90 89 110 111 115 110 The high values obtained in the presence of m-phenylenediamine were due to an increase in optical density contributed by the oxidation of m-phenylenediamine itself (see Table 11). The low values obtained in the presence of m-nitroaniline and 2-amino-4-nitrophenol were due to these substances decreasing the colour stability. Attempts were made to reduce these errors by acidifying the solution after formation of the colour. In this way it was hoped to stabilise the red colour of 2-amino-4-quinoneimine and reduce the colour contribution of m-phenylenediamine. Addition of 1 ml of 2 N hydrochloric acid lowered the pH of the solution to about 1-0, at which value the red colour of 2-amino-4-quino- neimine is stable, but recoveries were not improved (see Table 111).CONCLUSIONS 2,4-Diaminophenol and its salts may be accurately determined by the proposed method in pure aqueous solution and in urine. In the presence of similar amounts of uut-nitroaniline or m-phenylenediamine errors of the order of 5 or 10 per cent., respectively, are incurred. Occasionally, when it is necessary to determine 2,4-diaminophenol in the presence of such large amounts of m-nitroaniline or m-phenylenediamine, corrections for these substances should be made, since the instability of the diaminophenol makes preliminary separation exceedingly difficult. I thank Professor R. T. Williams for his interest in this work. REFERENCES 1. 2 . 3. 4. 5. 6. 7. 8. Shupe, I. S., J . Ass. Off. Agric. Chem., 1943, 26, 123. hllan, 2. J., and Muiik, F., Chem. Listy, 1953, 47, 380. Maren, T. H., J . Pharmacol., 1949, 96, 251. Ogino, S., and Yasukura, K., Amer. J . Ophthal., 1957, 43, 936. Parker, V. H., Biochem. J., 1952, 51, 363. Parke, D. V., and Williams, R. T., Ibid., 1957, 67, 7 ~ . Kehrmann, F., and Prager, H., Bey., 1906, 39, 3438. Piccard, J., and Larsen, L. M., J . Amer. Chem. SOL, 1918, 40, 1085. Received August 29tk, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600012

出版商:RSC    

年代:1961

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN96186BP013

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

16 HODGKINSON AND ZAREMBSKI THE DETERMINATION [Vol. 86 The Determination of Oxalic Acid in Urine BY A. HODGKINSON AND P. M. ZAREMBSKI Medical Research Council Unit for Metabolic Disturbances in Surgery, The General Infirmary, Gveat George Street, Leeds 1) A modified extraction with ether and colorimetric procedure are described for the determination of oxalic acid in urine; the method has increased accuracy and sensitivity compared with previous methods. Urine is acidified with hydrochloric acid and "half-saturated" with ammonium sulphate. The gelatinous precipitate formed after standing is removed by filtration, and the filtrate is continuously extracted with peroxide-free ether. The extracted oxalic acid is precipitated as the calcium salt, reduced to glycollic acid by boiling with zinc and sulphuric acid and determined colorimetrically with chromotropic acid.Recovery of oxalic acid from urine was 98 f 2 per cent. The daily excretion of oxalic acid by normal adults ranged from 9.0 to 23.8 mg. THE method most commonly used for determining oxalic acid in urine involves preliminary heating of the sample with hydrochloric acid to convert any oxaluric acid present to oxalic acid.1y2 The urine is extracted with diethyl ether, and the extracted oxalic acid is precipitated as the calcium salt and determined with a standard solution of potassium perma11ganate.l9~,3,~,~ More recently, attempts have been made to increase the sensitivity and specificity of the method by reducing the precipitated oxalic acid to glycollic acid and determining this substance colorime tri cally wj t h 2,7-dihydroxynaph t halene6 9 s8 or 2,7-dihydroxynaph t halene- 3,6-disulphonic acid (chromotropic acid) .g ,lo The procedures recommended by Powers and Levatin2 and Dempsey, Forbes, Melick and HennemanlO have been re-examined, and the modifications listed below have been made.(i) Preliminary heating of the urine with hydrochloric acid, which results in the partial conversion of a number of urinary constituents to oxalic acid, has been omitted . (ii) An improved apparatus is used for the extraction with ether. (iii) Improved conditions for the quantitative reduction of oxalic acid to glycollic acid and for maximum colour development with chromotropic acid are introduced. The method described has been used extensively for determining oxalic acid in normal and pathological urines.ll > l 2 9 l 3 EXPERIMENTAL According to Eegriweg and MacFadyen,14 the reaction between formaldehyde and chromo- tropic acid is specific for formaldehyde.The procedures used for colour development are, in general, based on observations by MacFadyen,14 who recommended the use of 50 mg of chromo- tropic acid in 0.5 ml of water. This amount of chromotropic acid was found to be approxi- mately ten times greater than the minimum required and so gave rise to unnecessarily high readings for the reagent blank value. Purification of the commercially available chromotropic acid resulted in further decrease in the optical density of the reagent blank solution. Purifica- tion also resulted in increased sensitivity of the colorimetric reaction and in greater stability of the aqueous chromotropic acid reagent solution.Maximum colour development of the chrornotropic acid - formaldehyde complex was attained after heating the reaction mixture in a boiling-water bath for 25 minutes, and a period of 30 minutes was adopted. Final dilution of the coloured complex with water has been used,15 but this leads to an appreciable loss of sensitivity. The final concentration of acid should be not less than 16 N.**14 According to MacFadyen,14 maximum optical density of the coloured complex is at 570 mp; we have confirmed this. Reduction of oxalic acid to glycollic acid by magnesium and sulphuric acid, as recom- mended by Pereira,s gave a satisfactory calibration graph (see Fig. 1, curve D), but greater sensitivity was attained by using zinc in place of magnesium.After heating with zinc for 2 hours at 35" C,2s10 reduction was incomplete a t higher concentrations (see Fig. 1, curve C). A more linear relationship was obtained after heating with zinc for 16 hours at 35" C (see Fig. 1, curve B), but the most satisfactory result was obtained after heating with zinc for 30January, 1961j OF OXALIC ACID IN URINE 17 minutes in a boiling-water bath (see Fig. 1, curve A). Calibration graphs plotted from the results obtained when oxalic acid and equivalent amounts of glycollic acid were used were almost identical, and it was concluded that reduction of oxalic acid to glycollic acid was complete under the conditions used. The isolation of oxalic acid from interfering substances present in urine is an essential preliminary step with the analytical methods available ; extraction with ether and then precipitation of oxalic acid as the calcium salt appeared to be adequate for this purpose.In view of the greater specificity of the formaldehyde - chromotropic acid colour reaction com- pared with titration against permanganate, the possibility was considered that precipitation of oxalic acid after the extraction might be omitted, but this resulted in appreciably higher values being found for urine. I 0 Amount of anhydrous oxalic acid present,pg Fig. 1. Relationship between concentration of anhydrous oxalic acid present and optical density: curve A, reduction by zinc after heating for 30 minutes in a boiling-water bath; curve B, reduction by zinc after heating for 16 hours a t 35" C; curve C, reduction by zinc after heating for 2 hours a t 35" C; curve D, reduction by magnesium Conditions for the quantitative extraction of oxalic acid with ether are relatively critical.The efficiencies of three types of liquid - liquid extractor were compared by measuring the recovery of oxalic acid from aqueous solution. Recovery was 94 per cent. for the apparatus recommended by Powers and Levatin2 and 72 to 78 per cent. for a standard Quickfit & Quartz assembly with a sintered distributor. 1 per cent. when the apparatus shown in Fig. 2 was used, With laboratory-grade ether, maximum recovery of oxalic acid was 92 per cent. after 4 hours and recovery decreased progressively with longer periods of extraction.With peroxide- free ether, recovery was 94 per cent. after 6 hours and 95 per cent. after 10 hours. Recovery was 97 per cent. after "half-saturation" of the aqueous phase with ammonium chloride and extraction with peroxide-free ether for 6 hours. When the ammonium chloride was replaced by ammonium sulphate, the recovery on replicate determination was 98 & 1 per cent. The optimum temperature of the bath for the extraction with ether was 70" C, longer extraction periods being required below 65" C. Loss of ether and oxalic acid occurred at temperatures above 70" C because of the limitations of the condenser. Recovery from aqueous solution was 9818 HODGKINSON AND ZAREMBSICI : THE DETERMINATION [Vol. 86 METHOD APPARATUS- Standard Quickfit & Quartz glassware was used when possible. The inner assembly, A, was constructed from Pyrex-glass tubing of diameter 043,143 and 2.5 cm ; it consists of a collecting funnel terminating in a perforated bulb, and an outer tube of capacity approximately 35 ml.The upper end of this tube is slightly constricted so that assembly A is a single unit. An extractor tube (Quick- fit & Quartz No. FC6/23A), a jacketed coil condenser (No. CX6/05) and a 250-ml conical flask (No. FE250/3) complete the assembly. Conical centrifuge tubes-These tubes were made from Exelo stoppered 25-ml test-tubes by drawing the closed end out to obtain a tip of internal diameter approximately 1 mm. The external tip of the tube was flattened to prevent it penetrating the rubber lining of the centrifuge buckets.Extraction apparatus-The apparatus used is shown in Fig. 2. To condenser I R Extractor tube Septum inner assembl y(A) Perforations (- 0.4 mm diameter) Scale cm Conical flask- Fig. 2. Extracticln apparatus REAGENTS- Allantoin-Prepare as described by Hawk, Oser and Summerson.16 Ammonium zcrate-Dissolve 4 g of uric acid in 100 ml of water to which has been added a few drops of 40 per cent. w/v potassium hydroxide solution. Cool, and add 20 g of ammonium chloride and then 3 ml of ammonia solution, sp.gr. 0.880. Set aside overnight, filter, wash the precipitate with dilute ammonia solution, and dry in a vacuum desiccator. Calcium chloride solution-Dissolve 90 g of analytical-reagent grade calcium carbonate in 450 ml of 4 N hydrochloric acid, and dilute to 500 ml with water.Chromotropic acid solution-Twice recrystallise the sodium salt of chromotropic acid from aqueous ethanol, and dissolve 1 g in 100 ml of water. Store this solution in the cold, and prepare freshly every 3 days. Ethanol - acetic acid mixture2-Mix 2 per cent. v/v acetic acid, 95 per cent. v/v ethanol and water in the ratio 1 : 6 : 2. Diethyl ether, peroxide-free-Pass anaesthetic-grade ether slowly through a 22-cm x 3-cm column of “aluminium oxide for chromatograplnic analysis” (obtainable from the British Drug Houses Ltd.). Store the product in the cold in a dark bottle containing a few pieces of copper wire, and prepare freshly every 10 days. Oxalic acid standard-Dissolve 1.0231 g of potassium oxalate monohydrate in 100 ml of water.Prepare a working standard by mixing 1 volume of this solution with 4 volumes of water; this solution contains 1 mg of anhydrous oxalic acid per ml.January, 19611 OF OXALIC ACID IN URINE 19 Oxaluric acid-The sample used was purchased from Nutritional Biochemicals Corpora- tion, Cleveland 28, Ohio, U.S.A., and contained less than 0.05 mg of oxalic acid per 100 g. PROCEDURE- Collect the urine at 4" C, without preservatives, and analyse as soon as possible after completion of collection. Mix a 50-ml sample of urine with 19 g of ammonium sulphate, and add 5ml of concentrated hydrochloric acid. Note the change in volume, set the mixture aside a t room temperature for 30 minutes, and filter through a Whatman No. 1 filter-paper. (Full saturation of urine with ammonium sulphate is recommended if an appreciable amount of heat-coagulable protein is present).Extract 20 ml of filtrate for 6 hours with 100 ml of ether, maintaining the temperature of the water bath at 65" to 70" C. Add 4 ml of water to the extract, and remove the ether by evaporation on a boiling-water bath; stop the evapora- tion at the first appearance of condensed water vapour. Transfer the aqueous liquor to a conical centrifuge tube with three 2-ml portions of 95 per cent. ethanol, and wash the apparatus with 2 ml of water. Add 50 per cent. v/v ammonia solution until the contents of the tube are alkaline to bromocresol green (3 to 4 drops will be needed), and then add 0.5 ml each of glacial acetic acid and 20 per cent. w/v calcium chloride solution. The final pH should be within the range 3-6 to 4.5.Cover the mixture with 2 ml of ethanol - acetic acid mixture, and set aside overnight at room temperature. Spin in a centrifuge at 1200 g for 20 minutes, remove the supernatant liquid with a Pasteur pipette, and allow the inverted tube to drain. Wash the precipitate once with 4 ml of ethanol - acetic acid mixture, remove the supernatant liquid, and dry the precipitate at 100" to 110" C. Dissolve the precipitate in 2 ml of 2 N sulphuric acid, add 100 to 150mg of powdered zinc, and heat in a boiling-water bath for 30 minutes. Spin in the centrifuge to separate the excess of zinc from the solution, and transfer 0.2 ml of the supernatant liquid to a glass-stoppered 25-ml test-tube containing 0.5 ml of chromo- tropic acid solution.Add 5ml of concentrated sulphuric acid, and heat in a boiling-water bath for 30 minutes. Cool, dilute to 20 ml with 0 N sulphuric acid, and measure the optical density a t 570 mp in a 10-mm fused-glass cell. The colour is stable for at least 2 hours. PREPARATION OF CALIBRATION GRAPH- Place 0, 0.2, 0.4, 0.6, 0.8 and 1.0 ml of working standard oxalic acid solution in separate test-tubes. Adjust the volumes to 1 ml with water, and add 1 ml of 4 N sulphuric acid and then 100 to 150 mg of powdered zinc to the contents of each tube. Treat the solutions as described above, and express the result in milligrams of anhydrous oxalic acid. The coloured complex obeys Beer's law closely (see Fig. 1, curve A); variations in the slope of the graph are small and are due mainly to differences between batches of chromotropic acid reagent.RESULTS RECOVERY OF OXALIC ACID FROM URINE- duplicate; the results are shown in Table I. The recovery of oxalic acid added to three different samples of urine was determined in TABLE I RECOVERY OF OXALIC ACID ADDED TO URINE Oxalic acid Sample found in control, NO. mg per 50 ml 1.056 1.054 0.840 0.843 0-398 0.400 1 2 3 Oxalfc acid found after addition of 0-5 mg of oxalic Recovery, acid, mg per 50 ml % 1.540 97.0 1.549 99.0 1-320 96.0 1.330 97.5 0.898 100.0 0.895 99.0 Mean . . 98-1 -& 2.0 COMPARISON BETWEEN "FREE" AND "TOTAL" OXALIC ACID VALUES FOR URINE- Twenty-four-hour samples of urine from normal adults and from patients with renal calculus were collected in the cold, without preservatives, and the oxalic acid contents were determined (a) as described above and (b) after heating with hydrochloric acid, as recom- mended by Powers and Levatin2; the results are shown in Table 11.The value (B - A ) was20 HODGKINSON AND ZAREMBSICI : THE DETERMINATION [Vol. 86 found to vary considerably from individual to individual and, moreover, was not a constant fraction of the “free” or “total” oxalic acid. TABLE I1 COMPARISON BETWEEN “FREE” AND “TOTAL” OXALIC ACID VALUES FOR URINE Oxalic acid found when- - urine was acidified ’ Sample Value of NO. but not heated ( A ) , and heated (B), (B - A ) mg per 24 hours mg per 24 hours Urine from normal adz&-- 1 10.4 2 23.2 3 19.5 4 19.7 5 19.2 6 22.0 1 28.6 2 54.6 3 15.0 4 18.9 5 10.5 6 348-0 Urine from patients- 16.6 34.0 31-0 25.5 24.3 24.4 38.4 61-9 17.0 22-6 26.5 404-0 6.2 10.8 11-5 5.8 5.1 2.4 9.8 7.3 2.0 3-7 16.0 56-0 SPECIFICITY OF METHOD- The recovery of oxalic acid from aqueous solution and from normal urine was determined after the addition of various compounds known to give rise to oxalic acid under suitable con- ditions.Recoveries were determined before and after heating the mixtures on a boiling-water bath for 30 minutes. Glycine, alanine, ammonium urate, allantoin and creatinine were added in amounts approximately twice those normally found in urine. The amounts of glucose added corre- sponded to that found in mild and moderate glycosuria, and the amounts of ribose and oxaluric acid were appreciably higher than would be encountered in most normal or patho- logical urines.Of the compounds added, only oxaluric acid, ribose and glucose caused inter- ference in aqueous solution when preliminary heating was omitted. Ammonium urate, oxaluric acid, ribose, glucose and allantoin caused1 some interference in urine under the same conditions, but all the compounds examined caused appreciable interference when the urine was heated (see Table 111). TABLE I11 EFFECT OF VARIOUS COMPOUNDS ON RECOVERY OF OXALIC ACID FROM WATER AND URINE Recovery of oxalic acid from water when sample was- acidified, but acidified acidified, but acidified Recovery of oxalic acid from urinc when sample was- r A v r A -I _Addition to 50 ml of sample not heated, and heated, not heated, and heated, % % % % Xlanine (3 mg) . . . . .. 99 104 100 109 Ammonium urate (40 mg) .. 99 104 104 115 Allantoin (3 mg) .. . . 99 102 102 106 None . . .. . . .. 99 99 100 100 Glycine (9 mg) . . . . .. 99 111 100 115 Creatinine (80 mg) . . .. 99 99 100 108 Alloxan (50 mg) . . . . . . 99 117 100 125 Oxaluric acid (1 mg) . . . . 107 107 111 138 Ribose (200 mg) . . . . . . 108 114 102 107 Glucose (1.5 g) . . .. . . 129 142 111 133 DAILY EXCRETION OF OXALIC ACID BY NORMAL INDIVIDUALS- Glucose (250 mg) . . . . 108 123 102 112 The urinary excretion of oxalic acid by thirty-nine adults on a normal diet containing approximately 70 mg of oxalic acid per day ranged from 9.0 to 23.8 mg per 24 hours. Values for two normal children aged 2 and 5 years were 4.9 and 12.3 mg per 24 hours, respectively. For comparison, values reported by other workers are shown in Table IV.January, 119611 OF OXALIC ACID I N URINE TABLE IV DAILY EXCRETION OF OXALIC ACID BY NORMAL ADULTS ON NORMAL DIET 21 Reference* Widniark, E.M. P.17 Barrett, J. F.18 . . Powers, H. H., et aL2 Lamden, M. P., et al.19 Archer, H. E., et aL20 Dempsey, D. F., et al.lo This paper . . . . No. of adults - in series . . . . 34 . . . . 14 . . . . 7 . . . . 51 . . .. 6 . . . . 20 . . . . 39 * See reference list below. Oxalic acid excretion per 24 hours A v Range, mg Mean, mg 14.0 to 56.0 - 20.0 to 47.5 33.6 14.3 to 35.8 25.3 16.0 to 64.0 38.3 6.4 to 27.8 16.4 15.0 to 50.0 31.0 9.0 to 23.8 17.0 CONCLUSIONS The preliminary heating of urine with hydrochloric acid is not recommended, as it results in erroneously high values for oxalic acid; this effect is apparently caused by the partial conversion of several urinary constituents to oxalic acid or to compounds yielding fonnalde- hyde under the experimental conditions used.The increase in the measured amount of oxalic acid found after urine had been heated, shown as (B - A ) in Table 11, can largely be accounted for on the basis of the results in Table 111. Some interference by ribose, glucose, uric acid, allantoin and oxaluric acid occurred even when preliminary heating was omitted ; this is probably a consequence of heating during extraction with ether.21 According to Flaschentrager and Miiller,2l urine contains only very small amounts of oxaluric acid, and errors from this source are probably negligible. With the proposed procedure, the value found for oxalic acid in normal urine is probably about 5 per cent.too high as a result of interference by uric acid, allantoin and reducing sugars, and the error may exceed 10 per cent. if the urine contains greatly increased amounts of these compounds. The range of values found for the daily excretion of oxalic acid by normal adults agrees well with that reported by Archer, Dormer, Scowen and Watts2(). Preliminary heating of urine was omitted by these workers, and this probably accounts for the absence of higher values reported by other workers (see Table IV). The proposed procedure, after modification of the initial stages, can be used for deter- mining oxalic acid in food, when the problem of “oxalogenic” compounds is also encountered. The application of the method to the determination of oxalic acid in blood is being studied.We thank Dr. J. Dawson, Director of Research, Runwell Hospital, Essex, for his advice in the initial stages of this investigation. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. REFERENCES Dakin, H. D., J . Biol. Chem., 1907, 3, 57. Powers, H. H., and Levatin, P., Ibid., 1944, 154, 207. Salkowski, E., 2. physiol. Chem., 1900, 29, 437. Holmberg, C. G., Biochem. Z., 1927, 182, 463. Merz, W., and Maugeri, S., 2. physiol. Chem., 1931, 201, 31. Eegriwe, E., 2. anal. Chem., 1932, 89, 121. Calkins, V. P., I n d . Eng. Chem., Anal. Ed., 1943, 15, 762. Pereira, R. S., Mikrochemie, 1951, 36, 398. Eegriwe, E., 2. anal. Chern., 1937, 110, 22. Dempsey, D. F., Forbes, A. P., Melick, R. A., and Henneman, P. H., Metabolism, 1960, 9, 62. Hodgkinson, A., Proc. Roy. SOC. Med. 1958 51, 970. Hodgkinson, A., and Zarembski, P. M., J . Clin. Path., 1958, 11, 553. Pyrah, L. N., Anderson, C. K., Hodgkinson, A., and Zarembski, P. M., Brit. J . Urol., 1939,31, 235. MacFadyen, D. A., J . Biol. Chem., 1945,158, 107. Dagley, S., and Rodgers, A., Biochim. Biophys. Acta, 1953, 12, 591. Hawk, P. B., Oser, B. L., and Summerson, W. H., “Practical Physiological Chemistry,’’ Thirteenth Edition, J. & A. Churchill Ltd., London, 1954, p. 808. Widmark, E. M. P., Skand. Arch. Physiol., 1926,48, 61. Barrett, J. F., Lancet, 1942, ii, 574. Lamden, M. P., and Chrystowski, G. A., PYOC. SOC. Exp. Biol. Med., 1954,85, 190. Archer, H. E., Dormer, A. E., Scowen, E. F., and Watts, R. W. E., Clin. Sci., 1957, 16, 406. Flaschentrager, B., and Muller, B. P., 2. flhysiol. Chem., 1938, 251, 61. Received Jtdy S h , 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600016

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

22 OGDEN, WEBSTER AND HALLIDAY: DETERMINATION OF [Vol. 86 Determination of Biologically Soft and Hard Alkylbenzenesulphonates in Detergents and Sewage BY C. P. OGDEN, H. L. WEBSTER AND J. HALLIDAY (Chemical Division, Thomas Hedley 15 Co. Ltd., P.O. Box 155, City Road, Newcastle @on Tyne 1) An infra-red method is described for the quantitative determination of biologically “soft” (straight-chain) and “hard” (branched-chain) alkylbenzene- sulphonates in detergents and sewage. Manufactured detergents are hydrolysed with acid and extracted with light petroleum to remove fatty material, perfumes, etc. The alkylbenzenesulphonate is then converted to the heptylammonium salt and selectively extracted from an acid - ethanol - water solution with light petroleum. After removal of the solvent, the optical density is measured in carbon disulphide at 9.9 p (total alkylbenzenesulphon- ate) and in carbon tetrachloride at 7.31 p (biologically hard alkylbenzene- sulphonate) ; biologically soft alkylbenzenesulphonate is obtained by differ- ence.For sewage, the detergent is adsorbed on carbon; after desorption, the procedure outlined above is applied. IN recent years the widespread use of synthetic detergents containing tetrapropylenebenzene- sulphonates has posed difficulties for sewage works and water authorities and there have been many reports of persistent foaming in the works and at weirs on rivers. The Minister of Housing and Local Government set up a Standing Technical Committee on Synthetic Deter- gents to look into the problem, and, under the auspices of this Committee, the possible use of an alkylbenzenesulphonate of a type more readily decomposable biologically has been investigated.The new material is essentially a straight-chain alkylbenzenesulphonate, whereas the tetrapropylene material had a branched side-chain. Experiments have been carried out with the new material, both on pilot plant1 and full scale (the Luton Experiment). In order properly to evaluate the course of the Luton Experiment, it was essential to be able to deter- mine analytically the proportions of the two materials present in any given sample. Since none of the methods previously described for determining detergent in waters and sewage distinguishes between the two materials, there was need for a new method. EXPERIMENTAL Development of the method was in two stages: (a) purification of the alkylbenzenesul- phonate and (b) determination of the proportion of each type present.SAMPLING- To arrest the biological decomposition of synthetic detergent before analysis it was necessary to add a bactericide; 10 p.p.m. of mercuric chloride were found to be satisfactory. For sewage, the bactericide should be added immediately after the sample has been taken. RECOVERY OF DETERGENT FROM SEWAGE- The method used for recovery of alkylbenzenesulphonate was based on that described by Sallee and his co-workers2 This involves concentration of the detergent by adsorption on carbon, drying of the carbon and desorption by boiling with alkaline benzene - methanol mixture. Experiments showed that, for the recovery of up to 200 mg of alkylbenzenesulphonate, the amount of carbon could be reduced from 100 to 25 g, the bore of the glass column being halved.With the desorption mixture used by Sallee and his co-workers, the recovery of “hard” detergent was 95 per cent., but recovery of the “soft” type was only S5 per cent. Improvement was obtained by increasing the proportion of methanol and substituting chloro- form for benzene. Ammonia solution was more effective than alcoholic potassium hydroxide and, as it needed no special preparation, was simpler to use. With a mixture of 2000ml of methanol, 500ml of chloroform and 25ml of ammonia solution, spgr. 0.880, it was possible to obtain essentially complete desorption of both types of alkylbenzenesulphonate. The desorption mixture worked efficiently when passed down theJanuary, 19611 BIOLOGICALLY SOFT AND HARD ALKYLBENZENESULPHONATES 23 column at room temperature, pre-drying of the carbon and boiling with solvent being un- necessary.This revised procedure needed only one-quarter of the volume of solvent used in the original method and much reduced the time of analysis. PURIFICATION OF DETERGENT- Detergent products may contain anionic detergents other than alkylbenzenesulphonates, as well as foaming agents, perfumes, etc. In sewage there is a highly complex mixture of organic compounds, many of which are liable to interfere with infra-red determination. After removal of the desorbing solvent, Sallee and his co-workers2 effected purification by acid hydrolysis, neutralisation and extraction with light petroleum to remove some of the Wavelength, )-I Fig.1. Absorption spectra of capillary films of l-methylheptyl- ammonium salts of alkylbenzenesulphonate : curve A, extract from sewage effluent treated by original methodz; curve B, extract from sewage effluent treated by proposed method; curve C, pure alkyl- benzenesulphonate impurities. Next, the alkylbenzenesulphonate was allowed to react with l-methylheptyl- amine, the heptylammonium salt was extracted with chloroform, and infra-red measurement was finally made in carbon disulphide, the characteristic bands at 9.6 and 9-9 p being utilised. This method gave no difficulty with manufactured detergents, but, when it was applied to settled sewage, the final solution was darkly coloured and contaminated by compounds that interfered with the infra-red determination.Investigations were therefore carried out to improve the purification and, if possible, to simplify the procedure. The acid solution was extracted with light petroleum to remove fatty acids and other impurities, ethanol being added to the aqueous phase to retain the detergent in solution and prevent formation of troublesome emulsions. After washing the light petroleum extract, the ratio of ethanol to water was adjusted to 1 to 4 and 1-methylheptylamine was added. The heptyl- ammonium salt was then extracted with light petroleum to give an almost colourless solution. This extraction was shown to be quantitative, provided that the ethanol content did not exceed 25 per cent. It had been sh0~113~4 that extraction of the heptylammoniurn salt with light petroleum was selective and separated the detergent from all known interferences.The extent of this improvement was shown by examination of the carbonyl bands at 5.85 p and methyl bands at 7-25 p on recovered alkylbenzenesulphonate. By the original method,2 the optical density of the carbonyl band was three to four times greater than that of the methyl band. By the After evaporation of the desorption solvent the residue was hydrolysed.24 OGDEN, WEBSTER AND HALLIDAY: DETERMINATION OF [Vol. S6 proposed procedure (see Fig. 1) the carbonyl band was reduced to approximately one-tenth of the methyl band and the background interference in the 9.5- to 10-5-p region was also removed. I I I I I I I 1 I I I 7.000 7.125 7.250 7.375 mi I I I I I 7.000 7.125 7.250 7.375 Wavelength.p Fig. 2. Absorption spectra of l-methylheptylammonium salts of alkylbenzenesulphonates in carbon tetrachloride : curve A, biologically hard alkylbenzenesulphonate ; curve B, 90 per cent. of hard and 10 per cent. of soft alkylbenzene sulphonate; curve C, 60 per cent. of soft and 40 per c,ent. of hard alkylbenzene- sulphonate ; curve D, biologically soft alkylbenzenesulphonate ; curve E, Luton final effluent; curve F, Luton final effluent pZus 10 per cent. of soft alkylbenzenesiilphonate; curve G, Luton settled sewage; curve H, Felling settled sewage. Peaks for soft and hard detergents shown a t 7.08 rind 7.31 p, respectively Several other amines-cyclohexylamine, A"'-diethyldiaminoethane, n-heptylamine, n-nonylamine, n-decylamine and n-dodecylamine-have recently been investigated for extraction of the alkylbenzenesulphonate. Of these amines, only n-heptylamine is satis- factory and its use improves the sensitivity of the infra-red measurement.INFRA-RED MEASUREMENT- In the method described by Sallee and his co-workers,2 total detergent is calculated from the optical densities at 9.6 and 9.9 p. It was found, however, that equal weights of the two types of alkylbenzenesulphonate, although giving the same optical density at 9-9 p, showed a 4 per cent. difference at 9.6 p. Consequently, only the band at 9.9 p was used to measure total detergent.January, 19611 BIOLOGICALLY SOFT AND HARD ALKYLBENZENESULPHONATES 25 Following the experimental use of the soft alkylbenzenesulphonate, the Department of the Government Chemist reported to the Standing Technical Committee that the two types of detergent showed different frequencies for the overtone sulphonate band in the 7.0- to B F L1 n R;IY- 7.000 7.125 7.250 7.375 7.000 7.125 7.250 7.375 Wavelength, p Fig.3. Absorption spectra of hard and soft alkylbenzenes and their heptylammonium sulphonates in carbon tetrachloride : curve A, soft alkylbenzene; curve B, 1-methylammonium soft alkylbenzenesulphonate; curve C, n-heptylammonium soft alkyl- benzenesulphonate; curve D, 1-methylheptylamine; curve E, hard alkylbenzene ; curve F, 1-methylheptylammonium hard alkylbenzenesulphonate ; curve G, n-heptylammonium hard alkylbenzenesulphonate ; curve H, n-heptylamine 7.5-p region and that quantitative determination of a mixture of the two sodium alkylbenzene- sulphonates was possible at 7.08 and 7.13 p, with reasonable precision, down to at least 10 per cent., provided that no interfering materials were present.The soft and hard alkylbenzenes also exhibit differences in the 7.0- to 7-5-p region of the spectrum. The hard type has bands at 7.20, 7-24 and 7.31 p, but the soft type has a band only at 7-24 p. The presence of a band at 7-31 p in alkylate shows that hard material is present. In practice, the soft alkylbenzene produced commercially has been shown to contain up to 10 per cent. of the hard type. The heptylammonium salts of the alkylbenzenesulphon- ates show two new peaks-one at 7-08 p for soft and one a t 7.13 p for hard detergents; also, there is an increase in the intensity of the peak at 7-24 p for the heptylammonium salts.Thus there are three bands that could be used for identifying and determining soft and hard detergents in the presence of each other-7.08 p for the soft and 7.13 or 7.31 p for the26 OGDEN, WEBSTER AND HALLIDAY : DETERMINATION OF [Vol. 86 hard type. The peaks at 7.08 and 7.13 p are in close proximity and cause background interference, but the change in background for the peak at 7.31 p due to the peak at 7.24 p is small, because the intensity of the band a t 7-24 p is approximately the same for both soft and hard detergent - heptylammonium salts. It was therefore found better for quantitative determination to measure the hard-detergent clontent at 7.31 p and the total detergent at 9 .9 0 ~ and to obtain the soft-detergent content by difference. Confirmation of the results for soft detergent may be obtained by comparing the peak at 7-08 p with known standard curves. Carbon tetrachloride is used for readings in the 7-0- to 7-5-p region and carbon disulphide at 9-90 p. The peak at 9.90 p has been attributed to a sulphonate band and that at 7-31 p to a gem-dimethyl band; the peaks at 7.08 and 7.13 p are believed to be due to overtone sulphonate bands. The use of n-heptylamine instead of 1-methylheptylamine causes a relative increase in intensity of the peaks at 7.08 and 7.13 p and hence increases the sensitivity of the method. Figs. 2 and 3 show typical infra-red curves in the 7.0- to 7.5-p region of the spectrum.In Fig. 2, curves A, B, C and D are absorption spectra of heptylammonium salts of pure alkyl- benzenesulphonates, and the change from hard (curve A) to soft (curve D) can be clearly seen. Spectra of heptylammonium salts of alkylbenzenesulphonates recovered from settled sewage and effluent are also shown in Fig. 2 (curves E, F, G and H). Curve E is for Luton final effluent and, as expected, shows no peak for soft detergent at 7.08 p. Curve F is the spectrum of the same sample after the addition of 10 per cent. of soft detergent and shows the same relative absorption a t 7.08 p to curve E as curve :B does to curve A. Curve G is the spectrum of a typical Luton settled sewage of the period November, 1959; analysis gave 60 per cent. of soft detergent, and it can be seen that the curve is similar to the calibration curve for a solution containing 60 per cent.of soft detergent (curve C). Curve H is for Felling settled sewage before soft detergent became available in the area and shows no peak for soft detergent at 7.08 p. The spectra in Fig. 3 show the improvement in sensitivity attained by using n-heptyl- amine instead of 1-methylheptylamine for extracting the alkylbenzenesulphonate. The peak at 7.08 p on curve C (n-heptylamine) shows an increase in optical density of 25 per cent. over the corresponding peak on curve B (1-methylheptylamine). METHOD APPARATUS- is constricted at the lower end. resolution. REAGENTS- Adsorption column-A glass tube 50 cm long and 2.5 cm internal diameter. The tube In fra-red spectrophotometer-Grubb - Parsons, type GS2, or an instrument of equivalent All materials should be of recognised analytical grade. Activated carbon-Use the fraction of Nuchar C190 carbon retained on a 30-mesh sieve.Desorfltion solvent-Mix 2000 ml of methanol with 500 ml of chloroform, and add 25 ml Light petroleum, boiling range 40” to 60” C. n-Heptylamine or 1-methylheptylamine. Mercuric chloride solution, 5 per cent. w/v, aqiaeous. Place 25 g of carbon on a 30-mesh sieve, and wash with detergent-free water until free from carbon “fines.” Insert a cotton-wool plug into the column, and introduce the carbon via a large funnel by means of a jet of water. Insert a cotton-wool plug on top of the carbon, fill the column with water, and apply suction to the bottom or pressure to the top of the column to remove excess of water and to settle the carbon.of ammonia solution, sp.gr. 0*880. PREPARATION OF COLUMN- PROCEDURE FOR MANUFACTURED DETERGENT- Weigh a representative portion of sample containing approximately 1 g of alkylbenzene- sulphonate, dissolve it in water, and dilute to 1 litre. Measure 100 ml of the solution into a 600-ml beaker, add 25ml of concentrated hydrochloric acid, and boil gently for 1 hour,January, 19611 BIOLOGICALLY SOFT AND HARD ALKYLBENZENESULPHONATES 27 reducing the volume to about 90 ml. Continue as described under “Procedure for Sewage,” beginning at “Transfer with water to a 500-ml separating funnel. . . .” PROCEDURE FOR SEWAGE- Immediately after collection, add to the sample, as bactericide, mercuric chloride solution in the ratio of 2 ml per 10 litres. Place a portion of sample containing approximately 100 mg of alkylbenzenesulphonate into an aspirator bottle of suitable size, and pass the sewage through the carbon column at approximately 2 litres per hour.Then pass through the column 2-5 litres of desorption solvent at 25 to 30 ml per minute, and collect the eluate in two %litre beakers; maintain a head of solvent above the carbon during desorption. If traces of carbon are carried through, remove them by filtering the eluate through a sintered-glass filter of porosity 4. Evaporate the solvent on a steam-bath, and combine the solutions in a 600-ml beaker when their volumes have been sufficiently reduced. Dissolve the residue in approxi- mately 100 ml of distilled water, add 25 ml of concentrated hydrochloric acid, and boil gently for 1 hour on a hot-plate so that the volume is reduced to about 90 ml.Transfer with water to a 500-ml separating funnel previously calibrated at 100 ml, and dilute to this volume. Rinse the beaker and transfer funnel with two 10-ml portions of ethanol, and reserve the beaker for the subsequent amine - light petroleum extract. Cool the separating funnel, and add 50 ml of light petroleum to its contents. Shake for 2 minutes, allow to settle, and run the aqueous layer into a second separating funnel, leaving interfacial solids in the light petroleum layer. To the light petroleum extract add 15ml of ethanol, shake to dissolve the interfacial solids, add 15 ml of water, and shake for 1 minute. Run the wash layer into the main aqueous layer, and repeat the washing once more with further 15-ml portions of ethanol and water, adding the wash layer to the main aqueous layer.Discard the light petroleum extract. To the main aqueous layer and washings add 1 ml of heptylamine and then 70 ml of water to bring the ratio of ethanol to water to 1 to 4. Extract with a 100-ml portion and then with four 50-ml portions of light petroleum, shaking the funnel for 2 minutes at each extrac- tion. Filter the extracts through a small plug of cotton-wool into the 600-ml beaker previously reserved, and evaporate the solvent on the steam-bath. Dissolve the residue in methanol, transfer to a 50-ml calibrated flask, dilute to the mark, and mix. By pipette, place a 5-ml and a 25-ml aliquot in separate 50-ml beakers, and evapo- rate them to dryness on the steam-bath.Dissolve the residue from the 5-ml aliquot in 2 to 3 ml of carbon disulphide, transfer the solution completely to a 5-ml calibrated flask, dilute to the mark, and mix. Scan the spectrum of this solution from 9.0 to 10.5 p ; use 0-8-mm reference and blank balanced cells at a scanning speed of 1 p in 4 minutes. Measure the optical density of the band at about 9.9 p ; use a suitable base-line tangent to overcome background inter- ference. From a calibration graph determine the equivalent amount of total alkylbenzene- sulphonate in the aliquot ( A mg). Dissolve the residue from the 25-ml aliquot in 1 ml of carbon tetrachloride, and transfer the solution completely, by pipette, to a 2-ml calibrated flask.Dilute to the mark, and mix. Scan the spectrum of this solution from 7.0 to 7-5 p ; use 0.8-mm reference and blank balanced cells at a scanning speed of 1 p in 16 minutes. Measure the optical density of the band at about 7-31 p ; use a suitable base-line tangent, as shown in Fig. 2 (curve A). From a calibration graph calculate the equivalent amount of hard alkylbenzenesulphonate in the aliquot (B mg) . Calculate the hard-detergent content of the alkylbenzenesulphonate from the equation- 20B Hard-detergent content, yo = - A and the soft-detergent content from the equation- Soft-detergent content, yo = 100 - Hard-detergent content. NoTE-AI~ samples of sewage effluent analysed showed little or no soft alkylbenzenesulphonate. However, it was found that the ratio of the optical densities at 9-9 p (total alkylbenzenesulphonate) and 7.31 p (hard alkylbenzenesulphonate) was not the same as that for manufactured detergents and settled sewage.This difference was attributed to partial break-down of the detergent, thereby lowering the molecular weight. When applied to effluents, the calculation gave high values for soft-detergent content; for such samples it was preferable to determine the proportion of soft detergent by visually evaluating the peak at 7.08 p (soft detergent) in relation to that of known mixtures.28 OGDEN, WEBSTER AND HALL1:DAY: DETERMINATION OF [Vol. 86 CALIBRATION- Prepare aqueous solutions of the types of soft and hard alkylbenzenesulphonates in current use and known mixtures containing 1 g of detergent per litre, and use appropriate aliquots.The soft alkylbenzenesulphonate should show little or no absorption at 7.31 p. For sewage, dilute the aliquots to 5 litres, and adsorb on carbon, etc., as detailed under “Procedure for Sewage.” R E s u r r s CALIBRATION- The infra-red spectra of solutions treated by the full procedure were compared with those of solutions extracted directly with heptylamine and light petroleum, i.e., omitting adsorption on carbon, desorption, hydrolysis and extraction with light petroleum. The recovery of total detergent by the full procedure was quantitative and the ra-tios of soft to hard detergent agreed closely with the theoretical values. Typical optical densities obtained during calibration with both l-methyl- and n-heptylamine are shown in Table I.Mixtures of the two types of alkylbenzenesulphonate were prepared. TABLE I CALIBRATION RESULTS With 1 -methylheptylamine With n-heptylamine Weight of alkylbenzene sulphonate in 50 ml of solvent,* mg 50(S) lOO(S) I50(S) 80(S) + 20(H) W S ) + 40W) 4 ~ ) + 6 0 ~ ) 20(S) + 80(H) 50(H) 100(H) 150(H) Optical density (0.8-mm cell) at- 9.9 Pt 0.102 0-208 0.305 0.20 1 0.201 0.207 0.205 0.105 0.208 0.301 7.08 pS 0.069 0.140 0.204 0.103 0.066 0-043 0.029 0.005 0.006 0.008 7.31 pS 0.009 0.01 1 0.0 13 0.057 0.106 0.159 0-215 0.132 0.261 0.396 r Weight of alkylbenzene sulphonate in 50 ml of solvent, * mg 7O(S) + 30(H) 6O(S) + 40(H) liO(S) + 50(H) 4O(S) + 60(H) 3O(S) + 70(H) :!O(S) + 80(H) l.O(S) + 90(H) 100(H) lOO(S) Optical density (0.8-mm cell) at- 9.9 P t 0.203 0.204 0.195 0.199 0.198 0.192 0.198 0.199 0.199 7-08 yS 0-176 0.092 0.077 0.065 0-045 0-031 0.020 0-013 Nil 0.012 0.077 0-107 0.138 0-157 0.1 88 0.223 0-247 0.267 * (H) = hard alkylbenzenesulphonate ; (S) = soft allrylbenzenesulphonate. t A 5-ml aliquot evaporated to dryness ; residue dissolved in 5 ml of carbon disulphide.+c A 25-ml aliquot evaporated to dryness; residue dissolved in 2 ml of carbon tetrachloride. MANUFACTURED DETERGENT- Production samples from plants making the two types of detergent have been analysed. Results for the product from a plant making on1.y hard detergent have invariably been 100 per cent.; typical results for soft-detergent contents for samples from a plant making mostly product of this type ranged from 92 to 98 per cent.The method was usefully applied when the latter plant began production of soft alkyl- benzenesulphonate, which was only a small fraction of the total output of detergent. The method was used successfully to monitor the production of soft detergent when changing from hard to soft alkylbenzene. To check the distribution of the product frequent retail purchases were made in the Luton area. Composite samples were analysed and the results were compared with an evaluation by carton codes. After the initial plant problems had been overcome, it was found that results by the two methods agreed to within 5 per cent. SEWAGE- When soft alkylbenzenesulphonate was introduced into the Luton area, the appearance of soft detergent was monitored in Luton settled sewage.As the new detergent became avail- able to consumers, the amount of soft detergent in the settled sewage slowly increased, over a period of several months, from 47 to almost 75 per cent. A check on manufactured detergent on sale in Luton shops in November, 1959, showed that 70 per cent. was of the soft type, and the comparative analysis of the settled sewage showed 63 per cent. The latter figure is always expected to be slightly lower, because of the delay between stocking in the shops andJanuary, 19611 BIOLOGICALLY SOFT AND HARD ALKYLBENZENESULPHONATES 29 use by consumers and possible decomposition during passage of the sewage to the sewage works. Known additions of soft alkylbenzenesulphonate were made to samples of settled sewage and effluent, and the soft-detergent contents were determined before and after the additions.The results are shown in Table I1 and indicate close agreement with the theoretical. Felling settled sewage A was sampled when no soft detergent was on sale in the area, and sampleB was taken some weeks later when soft detergent was becoming available. TABLE I1 RECOVERY OF ALKYLBENZENESULPHONATE ADDED TO SEWAGE SAMPLES Sample Felling settled sewage A . . Felling settled sewage B. . Luton settled sewage . . Prudhoe settled sewage* Luton effluent . . . . Prudhoe effluent* . . Felling effluent . . . . Soft-detergent content of alkylbenzenesulphonate- WL 7 found expected after found after initially, addition, addition, % % % . . . . . . Nil 70 68 .. . . . . 11 63 61 . . . . . . 63 78 74 . . . . .. 11 46 48 30 28 20 18 18 14 . . . . 5 t .. 3t . . . . 37 .. . . . . . . * n-Heptylamine used for extraction of alkylbenzenesulphonate. t Estimated from band a t 7.08 p by comparison with standard curves. CONCLUSIONS The proposed method is satisfactory for determining biologically soft detergent in manu- factured detergents and sewage. It has been found most useful in the evaluation of the Luton Experiment and should be of value to sewage works and water authorities. The method is accurate to within k3 per cent. for manufactured detergents and to within 25 per cent. for sewage. REFERENCES 1. 2. 3. 4. Truesdale, G. A., Jones, K., and Vandyke, K. G., Water Waste Treatment J., 1959, 7, 441. Sallee, E. M., Fairing, J. D., Hess, R. W., House, R., Maxwell, P. M., Melpolder, F. V7., Middleton, Fairing, J . D., and Short, F. R., Ibid., 1956, 28, 1827. Webster, H. L., and Halliday, J., Analyst, 1959, 84, 552. F. M., Ross, J., Woelfel, W. C., and Weaver, P. J., Anal. Chem., 1956, 28, 1822. Received August 22nd, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600022

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

January, 19611 BIOLOGICALLY SOFT AND HARD ALKYLBENZENESULPHONATES 29 A Simple Titrimetric Method for the Assay of Thiols BY B. SAVILLE (The British Rubber Producers’ Research Association, 48-56 Tewin Road, Welwyn Garden City, Herts.) Aliphatic saturated and unsaturated thiols can be determined by their reaction with silver nitrate in aqueous pyridine. The pyridinium nitrate formed in direct equivalence to the -SH groups of the sample is then deter- mined by titrating with standard alkali. Provisional details of the accuracy and validity of this procedure are discussed. NUMEROUS methods are available for determining thiols either at the microgram level or for highly accurate determinations of purity on relatively large samples. Emmet Reid’s1 review of this general topic permits an appreciation of the various improvements that have been made in the main classical analytical approaches.Iodine-titration methods, based on the reaction- are of Limited general applicability, since, although reaction with some thiols, e.g., benzene- thiol,2 is virtually instantaneous and complete (especially in the presence of pyridine3), the 2RSH+ 1 2 -+ RSSR+2HI30 SAVILLE : A SIMPLE TI'I'RIMETRIC METHOD [Vol. 86 reactions of higher aliphatic thiols with iodine in benzene are slow> and it may be several hours before the excess of iodine can be confidently titrated. Further, iodine titration gives abnormal results with tertiary aliphatic t hiols. Determinations based on reaction of the thiol. with mercuric or silver salts, the excesses of which are noted by amperometric,6 potentiometric6 or chemical methods, do not suffer from the selectivity shown by the iodine methods.However, these methods are subject to inter- ference from ions, such as CN- and Br-, that fonn insoluble precipitates or stable complexes with silver ions6 Further, other organic sulphur compounds present in the thiol may form complexes with silver ions and so give results for thiol that are too high. Nevertheless, the reaction of thiols with silver ions provides a less ambiguous procedure for determination if we consider the protons released according to the equation- RSH+Ag+ + RSAg+H+ .. . . Determination of the acid liberated in this reaction rather than of the excess of silver salt left in solution (a procedure doubtful in neutral or acid solution, in which RSH is precipitated, usually, as AgSR.nAgNO,, where n is non-integral when silver nitrate is the precipitant) gives a direct measure of the -SH group, since it is only this group that can supply protons.Provided, therefore, that excess of silver salt is present after the silver mercaptide (AgSR) has been formed, there can be no interference by precipitable anions from neutral salts. Methods based on this theoretically more mature principle have been proposed by Sampey and Emmet Reid4 and by Mapstone.' The former workers4 utilised the related reaction involving mercuric chloride and titrated the liberated hydrochloric acid to a methyl red or methyl orange end-point ; the disadvantage mentioned was that the rather acidic solution at the equivalence point in the titration led to slightly low results.Titration to a higher pH was impossible, since mercuric oxide or hydroxide would have been formed, thereby invali- dating the titration. Mapstone7 used silver sulphate and titrated the liberated sulphuric acid. A simple procedure, suitable for determining the purities of higher aliphatic unsaturated and tertiary thiols, is proposed in this paper. A weighed amount of the thiol is added to an excess of silver nitrate dissolved in aqueous pyridine, the mixture is diluted with water, and the pyridinium nitrate formed is titrated with stanldard alkali to a phenolphthalein end-point. The reaction, involving co-ordinated silver ions (Py,Ag+), is- Py,Ag+ + RSH + (12 - 1)Py + PyH+ + AgSR . . . . (2 The use of the aqueous pyridine solvent has several advantages: (i) The thiol is soluble in this medium, so that the mercaptide precipitate does not occlude unreacted thiol.(ii) Since the silver ions are co-ordinated, there is little possibility of the phenol- phthalein end-point being in error. (iii) Decomposition of the silver salts of certain unsaturated thiols to silver sulphide, a reaction occurring in the presence of excess of free silver ions, is avoided. (iv) The removal of free protons, as PyH+, ensures that the mercaptide-forming reaction is quantitative and that the reverse of equation (1) is avoided. METHOD REAGENTS- Pyridine-AnalaR. Silver nitrate, approximately 0.4 M, aqueous. Sodium hydroxide, 0.1 N, aqueous-Standardise this solution with pure potassium hydrogen phthalate .PROCEDURE- To 15 ml of pyridine in a stoppered 250-ml conical flask add from a dropper an accurately weighed amount (0.0010 to 0.0018 mole) of the thiol. As soon as possible, gradually add from a pipette 5 ml of the silver nitrate solution. Insert the stopper, and set the flask aside for 5 minutes. Add about 100 ml of distilled water and 3 to 4 drops of phenolphthalein indicator solution, and titrate with 0.1 N sodium hydroxide to a light-pink end-point. Note that the end-point is often recognised as a change in the colour of the yellow silver mercaptide to white,January, 19611 FOR THE ASSAY OF THIOLS 31 as the pink tint of the supernatant aqueous phase is almost complementary to the yellow of the precipitate. A simple mixture of the silver nitrate solution and AnalaR pyridine was found to be neutral to phenolphthalein and sensitive to 1 drop of added 0.1 N sodium hydroxide; hence, no blank correction is necessary.CALCULATION- 10 ml of 0-1 N sodium hydroxide = 0.001 group equivalent of -SH. The percentage purity of the thiol is given by the expression- Titre of 0.1 N sodium hydroxide x Equivalent weight of thiol RESULTS Weight of thiol taken, g x 100 The proposed method was applied to a range of thiols. Ethanethiol and 2-methyl- propane-2-thiol (practical grade) were Eastman Kodak products. The others were synthesised by myself and by Messrs. D. Lee and B. R. Trego of these laboratories; details of the methods used will be published elsewhere. The results are shown in Table I and indicate that the method can be applied to the assay of both saturated and unsaturated primary and secondary thiols and to tertiary ali- phatic thiols.The validity of the method is shown particularly by the results for Z-methyl- pentane-2-thi01,~ since this compound was shown to be pure by careful gas - liquid chromato- graphic examination. It is therefore considered that the purities found for the other thiols can be accepted with confidence. Sample Ethanethiol' . * .. But-2-ene-l-thiol . . . . 2-Methylpropane-2-thiol . . 2-Methylpent-2-ene-l-thiol§ 4-Methylpent-3-ene-2-thiol . 2-Methylpentane-2-thiol . . 2-Methylpentane-3-thiol . . Heptane-4-thiol . . .. 3-Methylhexane-3-thiol . . Dodecane-l-thiol . . . . . . . I . . .. .. .. .. .. .. TABLE I PURITIES OF VARIOUS THIOLS .. .. . . . . . . . . . . .. . . Molecular weight 62-08 88-11 90.18 116-2 116.2 118.2 118.2 132.3 132.3 202.4 Weight of sample used, g 0.0906 0.1097 0.1224 0-2209t 0.1221 0.1249 0.1177 0.1249 0.0893 0.1637; 0*1660$ 0.1828 0.24887 0.1347 0.1345 0.2010 0.1486 0-1737 0-1481 0.1719 0.1546 0.1917 0.1972 0.1498 0.1296 0.2063 0.2079 Titre of 0.1 N sodium hydroxide, ml 14.65 17.85 13-45 24-25 13.40 13.70 12.95 11.60 8.20 18.25 18-40 15.50 21.10 11-60 11.50 17.20 12.80 14-95 12.55 14.55 12.80 14.10 14-45 11-25 9.75 10.00 10.10 Calculated purity, % 100.4 101.0 96.8 96.7 96.7 96-6 96.9 83.8 82.8 100.6 100.0 98.5 98.6 100.1 100.1 99.5 100.0 100.1 100.2 100.1 97.9 97.3 96.9 99.3 99.5 98.1 98.3 * Results for this thiol refer to the contents of commercially supplied ampoules immediately after being t Extra silver nitrate solution used because of high weight of sample.$ Commercial sample after re-fractionation. § Other isomeric thiols present in sample. The reproducibility of results by the technique can be judged from the results for but-2- ene-l-thiol and 4-methylpent-3-ene-2-thiol. These two sets of results suggest that a mean opened.32 [Vol. 86 deviation of 0.14 per cent. and a maximum deviation of 0.37 per cent. might be accepted as a provisional description of the consistency of the method. I am grateful to Mr. F. H. Devitt for experimental assistance in this work, which forms part of a programme of research undertaken by the Board of the British Rubber Producers’ Research Association. FOSTER AND MURFIN: IJSE OF ALGINIC ACID IN REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. Emmet Reid, E., “Organic Chemistry of Bivalent Sulphur,” Chemical Publishing Co. Inc., New Saville, B., J . Chem. SOC., 1960, 1730. Harnish, D. P., and Tarbell, D. S., Anal. Chem., 1949,21, 968. Sampey, J. R., and Emmet Reid, E., J . Amer. Chem. SOL, 1932, 54, 3404. Kolthoff, I. M., and Harris, W. E., Ind. Eng. Chem., Anal. Ed., 1946, 18, 161. Cecil, R., and McPhee, J. R., Bzochem. J., 1955, 59, 234. Mapstone, G. E., Austral. Chem. Inst., J . G. Proc., 1946, 13, 232 and 373. Lee, D. F., Saville, B., and Trego, B. R., Chem. & Ind., 1960, 868. York, 1958, Volume I. Received Judy 18th, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600029

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

32 FOSTER AND MURFIN: IJSE OF ALGINIC ACID IN [Vol. 86 The Use of Formaldehyde-treated Alginic Acid in the Chromatographic Determination of Organic Bases BY J. S. FOSTER AND J. W. MURFIN (Standards Department, Boots Pure Drug Co. Ltd., A irdrie Works, A irdrie, Scotland) Alginic acid, after suitable treatment with formaldehyde, can be used as a carboxylic cation-exchange medium for the quantitative separation of organic bases from solution. The adsorption from aqueous solution and subsequent elution and spectroscopic determination of fourteen organic bases, and also the determinations of codeine phosphate in Compound Tablets of Codeine B.P. and strychnine in Prepared Nux Vomica :B.P.C., 1954, and Tincture of Nux Vomica B.P. are described. Recovery experiments were satisfactory, and the assay results for codeine and strychnine in the pharmaceutical preparations agreed with those found by the official$ methods.THE chemical structure of alginic acid differs only :;lightly from that of oxycellulose. The use of oxycellulose as a carboxylic cation-exchange medium was described by Freeman1 and enlarged upon by Elvidge, Proctor and Baines2 and Elvidge and P r ~ c t o r . ~ However, oxycellulose is somewhat expensive and at present is not readily available in Britain, whereas alginic acid is cheap and easily obtainable. Both alginic acid and oxycellulose are practically insoluble in water; unfortunately, commercial algiinic acid swells on contact with water and in this condition is useless as an ion-exchange medium, as no liquid will pass through a column of it.It has been stated that the “gelling power” of alginic acid and its salts is a function of molecular weight, so it was thought that if commercial alginic acid could be broken down to less polymerised molecules, so that it lost the property of swelling in water, but at the same time retained its insolubility, it might also serve as a medium for adsorbing organic bases from solution. Several treatments, e.g., heating under reflux with water and with various concen- trations of hydrochloric and sulphuric acids, were tried without success. Specker and Hartkamp4 devised a method of minimising this adsorption of water and consequent swelling and, used alginjc acid for sepa.rating certain metallic ions from aqueous solution. Their method of preparation was to precipitate alginic acid from a solution of sodium alginate, separate the precipitate, steep it in methanol for several hours, wash it with acetone and dry it at a temperature not exceeding 50” C.Alginic acid so prepared did not immediately “gel” .when treated with water and was found quantitatively to remove some organic bases from neutral solutions of their salts-we obtained excellent recoveries of quinine and strychnine by the method described later. However, with certain bases having low extinction coefficients, e.g., atropine and methylamphetamine, when relatively large amounts were adsorbed on the column it was found that the top layer “gelled,” completelystoppingJanuary, 19611 CHROMATOGRAPHIC DETERMINATION OF ORGANIC BASES 33 any flow of liquid.Further, after being set aside for several days under water, the columns of alginic acid prepared by Specker and Hartkamp’s method became impervious to water or, at best, allowed a much diminished and inconveniently slow rate of flow, even after being stirred and then allowed to settle. Alginic acid prepared as described below was found to be free from these defects. It is known that heating with formaldehyde prevents “gelling” of starch, and, because alginic acid and starch have molecules of the same general type, it was thought that such treatment might have a similar effect on alginic acid, D e ~ e l , ~ while investigating the reaction of pectic acid with formaldehyde, mentioned that alginic acid reacted similarly and noted that the resulting product was insoluble in water. He also indicated that the pectic acid - formaldehyde complex could be used as a cation-exchange medium and mentioned the removal of copper and nicotine from aqueous solution, without giving any quantitative details.The product obtained by us did not form a gel when treated with water, was practically insoluble in water and was found quantitatively to adsorb organic bases from aqueous solu- tions of their salts. On elution with dilute sulphuric acid, a solution of the base suitable for spectrophotometric assay was obtained. Alginic acid, grade HA/LE, obtainable from Algin- ate Industries Ltd., Bedford Street, London, W.C.2, was used in this investigation. METHOD PREPARATION OF “NON-GELLING” ALGINIC ACID- A suitable amount of alginic acid was well mixed to a damp paste with formaldehyde solution (40 per cent.).This paste was heated in a loosely closed screw-capped jar at SO” C for 8 hours and was then transferred to a clock-glass and dried at 100” C. (Overheating should be avoided or the product will turn dark brown; this does not appear to be detrimental to the base-exchange properties, but the alginic acid is difficult to wash clean for use.) The resulting cake was broken up and sifted through 22- and 100-mesh B.S. sieves, the granular powder remaining between the sieves being reserved for use. PREPARATION OF COLUMN- Three grams of prepared alginic acid were made into a slurry with about 50 ml of 10 per cent. w/w sulphuric acid and transferred to the tube, which had been previously plugged with cotton- or glass- wool.The alginic acid was allowed to settle, and a second plug was placed on top to avoid disturbance of the upper surface of the column. The column was washed with N sulphuric acid until the washings had no measurable extinction between 220 and 350 mp and then with water until the effluent was no longer acid. A rate of flow of upwards of 5 ml per minute could be obtained without applying air pressure to the top of the column; in fact, pressure tended to compact the column material and so reduce the rate of flow. A rate of about 1 ml per minute was used to obtain the results in Table I, but results were similar when some of the experiments were repeated with a rate of 3 ml per minute. When not in use the column was left submerged in water.GENERAL PROCEDURE- The optical densities of nicotinamide and thirteen salts of different organic bases, dissolved in N sulphuric acid, were measured at their wavelengths of maximum absorption; 1-cm cuvettes were used, with N sulphuric acid in the comparison cuvette. Aqueous solutions of suitable concentration were then prepared, each of which was treated as described below. An aliquot was transferred to the column, which was then washed with two 25-ml portions of water, and the base was eluted with a suitable volume of N sulphuric acid, the optical density being measured at the peak wavelength, as before. Recoveries were based on comparison of optical densities before and after passage of the base through the column. All recoveries reported in this paper were calculated in this manner; details are shown in Table I.After elution of the base, the column was washed with water until free from acid, when Pyrex-glass tubes of internal diameter about 1-5 to 2 cm were used. it was ready for further use.34 FOSTER AND MURFIN: USE OF ALGINIC ACID IN [Vol. 86 APPLICATIONS OF THE METHOD Procedures for determining codeine phosphate in Compound Tablets of Codeine B.P. and of strychnine in Prepared Nux Vomica B.P.C., 1954, and in Tincture of Nux Vomica B .P. were adapted from existing methods involving use of oxycellulose columns? RECOVERY OF Compound used Adrenaline acid tartrate . . Atropine sulphate . . .. Cocaine hydrochloride . . Codeine phosphate .. Diamorphine hydrochloride Ethylmorphine hydrochloride Hyoscine hydrochloride .. Lobeline hydrochloride . . .. .. . . . . . . . . . . Methylamphetamine hydrochloride Morphine sulphate . . .. . . Nicotinamide .. .. . . Procaine hydrochloride . . .. Quinine hydrochloride . . .. Strychnine hydrochloride . . .. TABLE I ORGANIC BASES FROM -4QUEOUS SOLUTIONS Volume of solution placed on column, ml 10 50 20 10 20 20 10 10 25 10 10 5 10 10 Weight of compound placed on column, WZ 5 40 15 8 10 10 40 3 20 10 1 1 .3 2 Volume of sulphuric Wavelength acid of optical-density eluate, measurement, ml mCL 100 279 50 100 50 100 100 50 200 50 100 100 100 50 100 275 275 284 279 284 257 249 257 285 26 1 228 347 254 Recovery of base, 99.3 99.3 99.3 99.5 100.4 100.8 99.4 99.8 100.7 99.4 99.5 99-1 99-3 99.6 99.8 100.0 100.7 100.0 100.0 100.8 100.4 100.4 100.4 98.5 100.0 100-5 100.0 100.2 100.9 99.3 99-6 99.8 98.7 98.7 99.1 99.8 99.9 99.9 100.0 100,0 100.5 Yo COMPOUND TABLETS OF CODEINE B.P.- Elvidge has used oxycellulose to separate codeine from the other ingredients.His procedure was applied in this laboratory and later modified slightly in order to use alginic acid as base-exchange material. The method described below is based on Elvidge’s pro- cedure. To twenty tablets in a dry, stoppered flask add 200ml of water by pipette, and shake the flask for 20 minutes. Filter the contents through a Whatman No. 30 filter- paper, and reject the first few millilitres of filtrate. Pass 10 ml of filtrate through the column, and wash with two successive 25-1111 portions of water. Elute the codeine to volume into a 100-ml calibrated flask with N sulphuric acid, and measure the optical density of the eluate at 284 mp in a l-cm cuvette; use N sulphuric acid in the comparison cuvette.January, 1961 CHROMATOGRAPHIC DETERMINATION OF ORGANIC BASES 35 Low recovery of codeine phosphate might be expected, since the alkaloid has to be adsorbed from a solution more acid than that used in the simple recovery experiment already detailed.A standard solution of codeine phosphate in saturated acetylsalicylic acid solution was prepared, the concentration of codeine phosphate being that calculated to be present when the method was applied to the tablets. Recoveries of 100.0, 99.7, 99.0 and 99.7 per cent. were obtained ; these were calculated as previously described. In further recovery experiments, two mixtures were prepared (each equivalent to twenty tablets) from accurately weighed amounts of codeine phosphate, aspirin, phenacetin and tablet excipient. Four aliquots of each filtrate were assayed for codeine phosphate; the results were- These mixtures were examined by the proposed method.Recovery of codeine phosphate from mixture No. 1, % . . 100.0, 100.0, 100.0, 99.7 Recovery of codeine phosphate from mixture No. 2, % . . 99-5, 99.5, 99-8, 99.8 To examine the precision of the method further, determinations were made on aliquots of a filtrate obtained from twenty tablets. Weights of codeine phosphate found per tablet were 040771, 0.00771, 0.00766, 0.00769 and 0.00766 g. To compare the method with that described in the British Pharmacopoeia the results, taken at random, of a hundred determinations on production samples were examined.By the B.P. method, the range was 7-52 to 8.30mg of codeine phosphate per tablet, with a standard deviation of 0.13mg per tablet. The proposed method gave a range of 7.49 to 5.32 mg per tablet, with a standard deviation 0.13 mg per tablet. In these experiments, the optical density was compared with that of a batch of codeine phosphate used in preparing the tablets. TABLE I1 EXTINCTION VALUES FOR STRYCHNINE AND BRUCINE The solvent used was N sulphuric acid Measurements a t 262 mp Measurements at 300 m p A I 7 f 7 A No. of Average value Coefficient of Average value Coefficient of Alkaloid samples of Ei%m variation, of E:tm variation, % % Strychnine . . .. 5 318 0.71 4.59 4.0 Brucine .. .. 4 3 14 0.43 216 1-9 PREPARATIONS CONTAINING NUX VOMICA- strychnine content is given by the equation- Strychnine content, yo w/v = 040321A - 0*00467B, in which A and B are the optical densities (l-cm cell) of the solution a t 262 and 300 mp, respectively. This equation was derived3 from the values of E:Fm for the two alkaloids at these wavelengths (see Table 11); it was later emended in a personal communication from Mr. K. A. Proctor. These wavelengths were selected as being the most suitable because the composite absorption curve has a maximum a t 262 mp and a point of inflexion at 300 mp. For nine different preparations, Elvidge and Procto? found that strychnine and brucine could be quantitatively adsorbed on oxycellulose, washed free from impurities, eluted with acid and then determined by the two-point method.We have examined two of these preparations and have found that alginic acid can replace oxycellulose as column material. We see no reason to suppose that it would not be suitable for the others. TINCTURE OF Nux VOMICA I3.P.- A 10-ml portion of this solution was placed on a column consisting of 3 g of alginic acid, washed with 25 ml of ethanol and then with 50 ml of water, and the alkaloids were finally eluted to volume into a 50-ml calibrated flask with N sulphuric acid. Optical densities were measured at 262 and 300 mp in a l-cm cuvette. Six results of 0.125 per cent. and three of 0.126 per cent. of strychnine were obtained; the official chemical assay gave 0.125 per cent. of strychnine. Nux vomica contains strychnine and brucine in approximately equal proportions.The Five millilitres of sample were diluted to 100ml with 95 per cent. ethanol. Nine aliquots of the diluted tincture were treated in this way.36 REID AND TURNER THE DETERMINATION [Vol. 86 PREPARED Nux VOMICA B.P.C.- Two grams of the finely powdered sample were extracted continuously with 150ml of 70 per cent. ethanol for 2 hours. When cool, the extract was transferred to a 200-ml cali- brated flask and diluted to volume with 70 per cent. ethanol. A 5-ml portion of this solution was placed on a column consisting of 3 g of alginic acid. The column was washed successively with 10ml of ethanol, 50ml of chloroform, 10ml of ethanol and 50ml of water. The alkaloids were eluted to volume with N sulphuric acid into a 50-ml calibrated flask, and the optical densities of the eluate were measured at 262 and 300 mp.The assay was carried out in duplicate on two separate portions of the original sample, each of the two ethanolic extracts being assayed in quadruplicate. Strychnine contents of 1-24, 1-24, 1.25 and 1.25 per cent. and 1.27, 1-27, 1.27 and 1-27 per cent. were obtained. These results agreed well with the figure of 1.25 per cent. by the B.P. method. DISCUSSION OF THE METHOD Formaldehyde-treated alginic acid has been shown to act as an ion-exchange medium for the separation of organic bases from their solutions. It is similar in activity to oxy- cellulose and is superior to it in a number of ways. Alginic acid is much cheaper and is readily available in this country, but it requires treatment with formaldehyde before it can be used with aqueous solutions, whereas oxycellulose can be used directly as received.Formaldehyde-treated alginic acid is more stable and does not need to be stored in a refriger- ator (as does oxycellulose). In our hands, after a few weeks of use, columns of oxycellulose have compacted so tightly as to give an inconveniently slow rate of flow, which could not be improved by stirring the column and allowing it to settle. By contrast, columns of formalde- hyde-treated alginic acid (3 g) have been in daily use for more than 6 months with no more treatment than occasional stirring and settling and then decantation of fines, without any noticeable decrease in the rate of flow. In experiments to check the adsorbing power of formaldehyde-treated alginic acid, a 3-g column adsorbed 100mg of strychnine (as 5-ml aliquots of a 0.1 per cent. solution, washing with 50 ml of water after each aliquot at. a flow rate of 4 ml per minute) ; the liquid leaving the column was free from strychnine during the experiment. The carboxylic acid content of the dried powder after treatment with formaldehyde, calculated from a potentiometric titration of the acidity, was about 25 per cent. for the HA/LE grade of alginic acid. REFERENCE s 1. 2. 3. 4. 5. Freeman, F. M., J . Pharm. Pharmacol., 1956, 8, 42. Elvidge, D. A., Proctor, K. A., and Baines, C. B., Analyst, 1957, 82, 367. Elvidge, D. A., and Proctor, K. A., J . Pharm. Pharmacol., 1957, 9, 974. Specker, H., and Hartkamp, H., 2. anal. Chem., 1953, 140, 167. Deuel, H., Helv. Chim. Acta, 1947, 30, 1269. Received August 19th, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600032

出版商:RSC    

年代:1961

数据来源: RSC

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36 REID AND TURNER THE DETERMINATION [Vol. 86 The Determination of Water in Plastic Materials BY V. W. REID AND L. TURNER (Petrochemicals Limited, Carrington Researcia Laboratory, Urmston, Manchester) A Karl Fischer titration procedure has been developed for the direct The method has proved particu- determination of water in plastic materials. larly useful for the determination of water in black polyethylene. THE presence of water in plastics may be deleterious for a number of reasons. For instance, it is well known that polyethylene containing carbon black may absorb moisture, which will give rise to extrusion problems, such as bubbling, (luring subsequent processing. It is there- fore desirable to be able to determine trace amounts of water in plastic materials. Methods involving use of drying procedures for determining water in plastics are unsatis- factory, as they do not distinguish between water and any other volatile material that may be present.Water present on the surface of polymer granules may be determined readily byJanuary, 19611 OF WATER I N PLASTIC MATERIALS 37 titration with Karl Fischer reagent. The polymer granules are introduced into a cell contain- ing the neutralised reagent and the free water is titrated directly. Low values are usually found for surface moisture, however, even when the properties of the product indicate high contamination by water. The total moisture present, including that absorbed internally by the granules, must therefore be determined, in order that the result will relate to the performance of the product.Haslam and Clasper1 determined the total-water content of nylon by heating the sample under vacuum and collecting the vaporised water in a cold trap; the contents of the trap were titrated with Karl Fischer reagent. Quantitative trapping of the liberated water may be difficult under these conditions, however, particularly when the water content is low. Our procedure for determining the total-water content of plastic materials also involves use of Karl Fischer reagent, but the method for separation and subsequent titration of the water is different. Our method consists in passing a stream of dry nitrogen over the sample, I, ''/ 2-rnf microburette To reagent-burette - To " dead-stop " - indicator apparatus -Nitrogen in Fig. 1. Apparatus for determining water in plastic materials which is maintained at 120" C.The water evaporates from the sample into the stream of nitrogen, which is passed into a Fischer cell, where the water is titrated with Karl Fischer reagent. The water usually volatilises from the sample in about 15 minutes, and nitrogen is passed for a further 15 minutes to ensure that the sample is dry. The total time for a determination is therefore about 30 minutes, and tests may be carried out consecutively without loss of time between them. METHOD APPARATUS- It consists of a pressure-control arm for the nitrogen supply and a drying tower to remove any water present in the nitrogen. The sample is contained in a glass tube fitted with a stoppered side-arm. The nitrogen enters the sample tube at the bottom, passes through the hot sample and thence to a Karl Fischer titration assembly designed for the analysis of gases.The cell contains about 20 ml of reagent at the beginning of a test. The "dead-stop" end-point indicator consists of a simple potentiometer circuit , which applies an e.m.f. of 100 mV to the electrodes of the titration cell; the current flowing is indi- cated on a miuammeter connected in series with the cell. Such a circuit has been described by Mitchell and Smith.2 The analytical train is shown in Fig. 1.38 REID AND TURNER: THE DETERMINATION [Vol. 86 REAGENTS- KarZ Fischey reagent-Prepare the reagent as described by Peters and J~ngnickel.~ This solution has low volatility and will not volatilise into the stream of nitrogen.Adjust the concentration of the reagent so that 1 ml is equivalent to approximately 3 mg of water, and standardise daily. Drying agent-Use anhydrous magnesium perchlorate for drying the nitrogen. PROCEDURE- Switch on the hot-plate, and adjust it so that the oil bath maintains a temperature of 120” C. Adjust the cell to the “dead-stop” end-point by titrating with reagent, and start a steady flow of nitrogen through the apparatus, which is assembled as shown in Fig. 1, the glass tube immersed in the oil bath being empty at this stage. Adjust the flow of nitrogen to about 0.5 litre per minute. Add 0.1 ml of Karl Fischer reagent to the contents of the cell; the “dead-stop” indicator will swing to the “dry” side. As the apparatus dries, traces of water will enter the cell and the indicator will slowly move back to the refe:rence point.As the indicator reaches the reference point, add a further 0-1-ml portion of reagent. Repeat additions of reagent in this way until nitrogen passes for 15 minutes without causing the “dead-stop” indicator to move from the “dry” side back to the reference point. The indicator will slowly reach the reference point, and, when this happens, remove the stopper from the side-am of the glass tube immersed in the oil bath. Rapidly transfer a weighed amount of polymer (about 20 g) to the tube, and replace the stopper in the side-arm. Note the volume of reagent in the burette, and atdd a 0.1-ml portion to the contents of the cell. Water liberated from the polymer passes to the cell and causes the indicator to move back to the reference point. Each time the indicator moves to the reference point, add a further 0.1 ml of reagent.When all the water has vaporised from the polymer, the nitrogen will pass for a long time while the “dead-stop” indicator remains on the “dry” side of the reference point. Take the end-point as being when a 0.1-ml portion of reagent keeps the indicator on the “dry” side of the reference point for 15 minutes. Record the volume of reagent added from the time that the sample was introduced, and calculate the water content of the polymer from the expression- The apparatus is now dry. V x F Water content, yo w/w = - w x 10 where V is the volume of reagent used, in millilitres, W is the weight of sample, in grams, and F is the concentration of the Karl Fischer reagent, in milligrams per millilitre.ACCURACY AND REPRODUCIBILITY The method has been found particularly useful for determining water in polyethylene stabilised with carbon black. To check the accuracy of the method in this particular applica- tion, we stored several weighed dishes, containing ;accurately weighed amounts of a sample of black polyethylene moulding nibs, in a desiccator over water. Water was determined on the original sample and a daily note was made of the increase in weight of each dish. We calcu- lated the increase in water content occurring each day through pick-up of moisture and added this to the determined water content of the original sample. This gave a daily value for the total water content of the nibs, the only assumption being that the original water determina- tion was correct.Each dish contained sufficient black polyethylene to allow us to carry out a water deter- mination, and parallel comparative water determinations by the proposed method were carried out over 7 days. The results were- Water content by weight increase, yo w/w . . - 0-071 0.084 0.090 0.100 0.113 Water content by proposed method, yo w/w . . 0-05 0.080 0-090 0.096 0-106 0.126 from which it can be seen that the direct determinations gave values in close agreement with the water contents obtained by measuring the increase in weight. At the end of the 7-day period the surface moisture on the two remaining dishes was determined by the direct Fischer titration method. The low values obtained for surfaceJanuary, 19611 OF WATER I N PLASTIC MATERIALS 39 water (0.013 agd 0-014 per cent. w/w) indicated that most of the water had permeated into the interior of the nibs and been adsorbed on the charcoal black. The method has now been regularly applied for some 2 years, during which time several hundred determinations have been made on a variety of plastic materials. The results obtained over this period indicate the reproducibility of the method to be of the order of - + 10 per cent. of the water content determined when this is in the region of 0.0 to 0-5 per cent. We thank the Directors of Shell Chemical Company Limited for permission to publish this paper. REFERENCES 1. 2. 3. Haslam, J., and Clasper, M., Analyst, 1952, 77, 413. Mitchell, J., jun., and Smith, D. M., “-\quametry,” Interscience Publishers Inc., New York, 1948, Peters, E. D., and Jungnickel, J. Id., Awal. Chew., 1955, 27, 450. Received July 18th, 1960 p. 86.

ISSN:0003-2654    

DOI:10.1039/AN9618600036

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

January, 19611 OF WATER I N PLASTIC MATERIALS 39 The Determination of Trace Elements Fast-neu tron Activation Analysis BY R. F. COLEMAN ( U . K. Atomic Energy ,4 uthority, Atomic Weapons Research Establishmepit, Aldermaston, Berks.) The use of fast neutrons in trace analysis is described. Details are given of a method of producing a large flux of 14-&MeV neutrons suitable for activa- tion analysis; the cost is about i20,OOO. Suitable reactions, together with cross-sections and probable limits of detection, are quoted for nearly all the elements of the periodic table. THE determination of trace elements by activation with thermal neutrons is now a well established technique1,2 and the sensitivity of this method for many elements is higher than that of any other conventional physical or chemical method.The chief disadvantage is the scarcity of reactors having suitable neutron fluxes and containing facilities for irradiation ; also, when the nuclear products are short they can only be examined in the vicinity of the reactor. To overcome these difficulties De and Meinke3 used a 1- to 5-curie antimony - beryllium source emitting about lo6 neutrons per second, but for most elements a higher neutron flux is required to attain the necessary sensitivity. One of the chief aims is to show that an adequate flux of fast neutrons for trace analysis can be obtained at comparatively low capital cost. Neutrons of 14 MeV are produced by bombarding a tritium target with deuterons from a suitable high-voltage generator, usually a Cockroft - Walton machine, and these are used to activate the samples for analysis.Many elements can be determined in this way with high sensitivity, and several common elements difficult or impossible to detect with slow neutrons can be readily determined by activation with fast neutrons. Fast neutrons have been little used in trace analysis, with the exception of the determina- tion of oxygen in berylli~m.~ Turner5 used fast neutrons in analysis, but to determine macro amounts of aluminium and silicon. In this paper the use of fast neutrons in analysis is discussed. NUCLEAR REACTIONS WITH 14-MeV NEUTRONS With slow neutrons, there is mostly only one possible neutron reaction, i.e., radiative capture, but with fast neutrons many reactions are possible, the most useful being (n,@), (%,or) and (.n,2n).With 14-MeV neutrons, the first two predominate for the lighter elements, but decrease with increasing atomic number ; the (.n,2n) cross-section increases with atomic number and for elements having atomic numbers greater than 50 is usually 1 to 2 barns. The cross-section for the (n,y) reaction is usually too small for analytical purposes. It has been measured by Perkin, O’Connor and Coleman6 and for most elements is about 5 milli- barns, but much less for light elements.40 COLEMAN : THE DETERMINATION OF TRACE [Vol. 86 This multiplicity of reactions widens the scope of the method, but it has one disadvantage. Sometimes the nuclide formed from one element may also be formed by another reaction from an element differing in atomic number by one or two. For example, 59Co(~,cc)56Mn and 56Fe(~z,fi)~~Mn have the same final product.Whenever possible, one should choose a reaction in which the nuclide produced cannot be formed from any other element. If this is not possible, and other reactions contribute significantly to the nuclide produced, the con t ribu t iori must be calculated and subtracted. PRODUCTION OF FAST NEUTRONS A large flux of fast neutrons is most conveniently produced by the deuterium - tritium reaction, i.e., 2H + 3H + 4He + ln. The cross-section for the deuterium - tritium reaction has a resonance at 107 KeV, so that, for maxirnum production of neutrons, the deuteron energy must be 107 KeV at some point in the target. In most of my work the deuterons were accelerated by a Cockroft - Walton machine t o energies of about 300 to 600 KeV.The tritium was usually in the form of a titanium or zirconium tritide target, 8 mm in diameter, and the deuterons were completely stopped in the target. When a target of about 5 mg of titanium per sq. cm and a titanium to tritium atom ratio of 1 was used with a 50-pA beam of D f ions, outputs of 3 x 1O1O neutrons per second were achieved, giving a flux of about 1O1O neutrons per second per sq. cm through a sample placed close to the back of the target. Other workers have produced larger yields of neutrons, e.g., Bronner and his co-workers’ claimed loll to 1012 neutrons per second from the Arkansas machine spread over a target 3.2 cm in diameter, but, because of the cooling system, only 7 per cent. of the neutrons will pass through 1 sq. cm of sample close to the back of the target.Gunnersen and James8 have shown that it is possible to produce 108 neutrons per pA per second with 125-KeV deuterons, provided that the amount of oxide and carbon on the surface of the target is very small. As ion sources capable of supplying as much as 10 mA of current are obtainable, it should be possible to produce 10l2 neutrons per second from a high-voltage power pack, provided that the target does not overheat. Above 230” C, the tritium targets begin to lose tritium, and a beam of 10 mA per sq. cm will rapidly exceed this temperature if special cooling is not applied. In addition to cooling the target area, the heat generated per sq. cm should be reduced. This is best achieved by having a large target, say, 50 sq.cm, and rotating it rather than by spreading the deuteron beam over a large area. By careful design it would still be possible to get one third of the neutron output through 1 sq. cm of sample close to the target. The cost of a high-voltage generator and ancillary equipment to give a 10-mA bpam of 150-KeV deuterons would be about @3000 to -QO,OOO. A source of 10l2 neutrons would require careful shielding (about 8 feet of concrete would be necessary). For activation analysis it is unnecessary to have a large scatter-free space around the neutron source and so the shielded volume could be small. It has been estimated that a building large enough to house the accelerator and controls and shield a target room 7 feet square and 7 feet high with concrete would cost E6000 to Ll0,OOO. A fairly versatile source of 10l2 neutrons could therefore be made for a capital cost of L20,OOO.For the purposes of this paper, however, a flux of 1010 neutrons through the sample will be assumed, as this is readily available in many laboratories. EXPERIMENTAL TECHNIQUES The sample to be irradiated must be placed as close to the neutron source as possible in order to get a maximum number of neutrons through it. Samples must also have a well defined shape so that the irradiation geometry is reproducible; this can be achieved by using a machined sample, as in the determination of oxygen in berylli~m,~ or, alternatively, a pow- dered sample supported in a plastic holder. The sample would normally be irradiated for a time similar to the half-life of the reaction product or for a few hours, whichever is shorter.The output of neutrons from the target is monitored by a “long counter,” the pulses being fed via a ratemeter into a fast recorder. The neutron output and the time of irradiation are measured on the recorder chart. At the end of the irradiation, the samples are counted directly or, more usually, treated by conventional chemical techniques to separate the desired nuclide from the impurities and then counted. For a residual nucleus having a half-life of the order of a few seconds, special techniques, such a:; those described by Coleman and Perkin,g for the precise timing of the irradiation and rapid transfer of the target to a counter or chem- ical-separation apparatus are necessary.January, 19611 ELEMENTS BY FAST-NEUTRON ACTIVATION ANALYSIS 41 To determine trace amounts of any element in a sample, both the sample and a standard of the same size containing a known, weighed and evenly distributed amount of the element being determined are irradiated, processed and counted in the same way.The activity of the trace element is normalised to a fixed neutron flux, and the amount of impurity in the sample can then be inferred from the standard. This method overcomes most of the difficulties in obtaining accurate results by eliminating errors in counter calibration and in variation of neutron flux through the sample. SENSITIVITY The sensitivity of the method for all the stable elements and uranium and thorium has been calculated, cross-sections taken from several SourceslO y 1 l ,12 9 1 3 being used ; the results are shown in Table I.For these calculations, a final activity of 100 disintegrations per minute was required when irradiated in a flux of 1O1O neutrons per second per sq. cm. The sensitivity has been calculated for irradiations of 4 hours and to saturation. (Generally, 4 hours would be as long as one would want to spend on the irradiation, particularly if the chemical separa- tions and counting had to be completed during the same day.) Some reactions have been included in Table I when the cross-sections are unknown, but the sensitivity for these elements would usually be at least 1 pg. As suggested above, it should be possible to produce fluxes of fast neutrons considerably larger than 1O1O and this would increase the sensitivity and make the method even more attractive for extremely small traces of elements.The intefering elements listed in Table I are those elements capable of producing the same nuclide by another reaction with fast neutrons. The ( n , ~ ) products are not listed, as these would normally be lower in intensity by a factor of 100 and could only interfere if present in considerable excess. TABLE I REACTIONS SUITABLE FOR FAST-NEUTRON ACTIVATION ANALYSIS No correction has been made for radioactive decay. Element Hydrogen Helium . . Lithium Beryllium Boron . . Carbon . . Nitrogen Oxygen . . Fluorine Neon .. Sodium . . Magnesium Aluminium Silicon . . Phosphorus Sulphur Chlorine. . Argon . . Potassium Calcium Scandium Possible reaction - .. - .. . . QBe(n,a)6He 11B(n,a) *Li - .. . . 14~(n,2n)13~ . . {19~(n,2+*~ 160(n,p)16N 20Ne(n,2n)1DNe 20Ne (n , p ) 20F . . 23Na(n,p)23Ne 35qn, 2434~1 . . 44Ca(n,p)44K . . *5Sc(n,2n)44Sc Cross- section, millibarns - I 6 10 ? 30 ? - 5 80 61 ? ? 34 190 60 114 80 200 100 8 80 370 4 28 ? ? 80 50 ? ? Half-life of product - 0.8 second 0-8 second 0.8 second 0-8 second 14 seconds 10 minutes 7-4 seconds 112 minutes 18 seconds 11 seconds 40 seconds 15 hours 1 minute 15 hours 9 minutes 2 minutes 6 minutes 2.5 minutes 2.6 hours 14 days 32 minutes 5 minutes 1.4 minutes 5 minutes 110 minutes 37 minutes 37 minutes 2.4 days - 4 hours and Sensitivity after irradiation- +- for 4 hours, Pg - - 4 0.2 ? 0.1 ? 0.8 0.06 0.1 ? ? 0.2 0-2 1.0 0.1 0.1 0.04 2.0 1.0 0.2 3.0 3-0 1.0 ? ? 3 4 ? ? - to saturation, Pg - - 4 0.2 ? 0.1 ? 0-8 0-06 0.08 ? ? 0.2 0.05 1.0 0.02 0.1 0.04 2.0 1.0 0.1 0.02 3.0 1.0 ? ? - 2 4 ? ? Interfering elements - Be Be Li - - S c1 A c1 Ca A - - -42 Element Titanium Vanadium Chromium Manganese Iron .. Cobalt . . Nickel . . Copper . . Zinc . . Gallium Germanium Arsenic . . Selenium Bromine Krypton Rubidium Strontium Yttrium. . Zirconium Niobium Molybdenum Ruthenium Rhodium Palladium Silver . . Cadmium Indium A4ntimony Tin . . Tellurium Iodine . COLEMAN : THE DETERMINATION OF TRACE Possible reaction 46Ti (n, 2ny5Ti 48Ti (~2,p)~~Sc 51V( ~ , p ) ~ l T i 52Cr(n,p)52V 50Cr(n, 2n)40Cr : : (.Mn(n,,,"V 56Fe (n,p)S6Mn 54Fe(n, 2 ~ ) ~ ~ F e - 59Co(n,a)56Mn 51V(n,a)48Sc ::[ .. . . . . . . . . - . . [ 902r(n,2489zr 94zr(n,p) 9 4 ~ 93Nb (n ,a) S3Nb (n, 2n) 92Nb 92Mo(n,2n)S1Mo 97Mo(n,p)97Nb 110Pd(n,2n)109Pd 105Pd (n, $)lo5Rh .. lo7Ag(n,2n)lo6Ag loOAg (n, 2n)lo8Ag 1'5In ( n,p)l15Cd ~ O O M O ( ~ Z , ~ W ) O ~ M O * . S ~ R U ( ~ , ~ V Z ) ~ ~ R U . . - * * ll6Cd(n,2n)ll5Cd 1131n(n, 2n)1121n .. 121Sb(n, 2n)120Sb 123Sb(n, 2n)122Sb : : (122Sn(n,2n)121Sn 12sTe(n,2n)1a7Te lsoTe (n, 2n)120Te . . 1271(n,241261 TABLE I (con.tinued) Cross- section, Half-life millibarns of product 50 58 27 30 78 ? 30 110 ? 31 180 52 600 954 27 200 390 530 700 24 39 700 1800 140 540 12 12 1500 40 1100 800 100 ? ? ? 40 18 60 80 11 10 ? 200 4000 110 480 2000 700 550 800 ? 15 ? 750 1200 ? 800 600 1350 - - 3 hours 4 4 hours 6 minutes 4 4 hours 3.7 minutes 42 minutes 3.7 minutes 2.5 hours 9 minutes 2.5 hours 99 minutes 3 6 hours 10 minutes 13 hours 2.5 hours 38 minutes 73 hours 68 minutes 21 minutes 13 hours 5 minutes 40 hours 86 minutes 5 hours 17 days 86 minutes 8 minutes 57 minutes 57 seconds arid 12 hours 5 6 minutes 44 hours 90 minutes 4-4 hours 32 minutes 78 minutes 32 minutes 18 minutes 4.4 hours - 4 minutes and 79 hours 16 minutes 64 hours 13 hours and 11 days 15 minutes 616 hours 7 3 minutes 98 minutes 1 :3 hours 38 hours 24 minutes 2-3 minutes 5:'.hours 5.5 hours 20 minutes 16 minutes 2.3 days 2'7 hours !J hours 72 minutes arid 33 days 13 days - Sensitivity after irradiation- +- for 4 hours, P.g 4 0.5 0.5 7 0.2 ? 0.5 0.2 ? 0.8 12 4 0.04 0.2 3 0.2 0.4 0-06 0-07 7 0.5 2 0.2 5 7 2 2 0.2 ( 5 0.04 0.1 0-5 ? ? ? 2 2 1 0.6 - 14 50 ? 1 2 3 1 0-4 2 0.1 0.08 ? 50 ? 0.08 2 ? 0.5 ? 3 - to saturation, Pg 3 0.03 0.5 0.5 0.2 ? 0.5 0.1 ? 0.6 0-3.0.04 0.06 2 0.2 0.1 0.06 0.07 1.0 0.5 0.1 0.1 2 0.05 2 2 0.2 1.0 0-04 0-05 0.5 ? ? ? 10 2 2 0.5 0.6 - 14 2 ? 1 0.07 2 1 0.1 0.2 0.1 0.08 ? 2 ? 0.08 0.07 ? 0.1 0.2 0.03 - [Vol. 86 Interfering elements - V Cr Ti Mn V c o Fe - - - - Zn Zn c u Ge Zn, Ge Zn As, Se Se Ge, Se Ge Br, Kr - - - - - Kr Kr Se Rb, Sr Rb Kr Rb, Kr Mo - - - - Zr Mo - Cd, Ag Cd Cd In, Sn Cd, Sn Sn Te Te Sb, Te I, Xe Xe - XeJanuary, 19611 ELEMENTS BY Element Possible reaction Xenon .. . . 136Xe(n,2n)135Xe 138Ba(n,2n)137Ba 136Ba(n,2n)135Ba Caesium.. . . 133cs (n, 24132Cs --{ 133Ba(n,P)138C~ Barium . . Lanthanum . . 13gLa(n,p)139Ba Cerium . . . . 142Ce(n,2n)141Ce Praseodymium 141Pr(n.2nP40Pr Neodymium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium .. Thulium Ytterbium Lutecium Hafnium Tantalum Tungsten Rhenium Osmium.. Iridium . . Platinum Gold . . Mercury.. Thallium Lead . . Bismuth Thorium Uranium . . 160Gd(n,2n)15gGd . . 15gTb(n,p)15gGd . . 162Dy(n,$)162Tb (Is6Er(n, 2 ~ 2 ) l ~ ~ E r * * 1170Er(n,2n)169Er . . 160Tm(n,a)166H~ . , 176Yb(n,2n)175Yb . . 165H~(~,2n)164H~ 175L~(n,p)175Yb . . 178Hf(n,p)178L~ : : (181Ta(n,2n)180Ta lE4W (n,$)lE4Ta . . 187Re(n,2n)186Re 175~u (n,24174~u lE6W (n , p ) ls6Ta . . 1920~(,,241910s . . 1g11r(n,2n)1g01r . . lg7Au(n, 2n)lg6Au . . l98Hg(n,2n)lg7Hg . . 20aPb(n,a)205Hg . . 20sBi(n,p)20gPb . . 198Pt(n,2n)’97Pt . . 203~1(~,24202~1 FAST-NEUTRON ACTIVATION ANALYSIS TABLE I (continued) Cross- section, millibarns ? ? 1200 700 2.2 2.3 1600 2100 2600 2160 2200 1200 1500 500 750 1450 ? ? ? 1000 1200 ? 430 1600 ? 900 3-4 4.7 2.9 ? ? ? 2800 2600 ? ? 1.5 1.3 1200 17 700 60 Half-life of product 9 hours 6.2 days 2-6 minutes 28 hours 32 minutes 85 minutes 33 days 3.4 minutes 2.5 hours 11 days 1 -8 hours 8.5 minutes 45 hours 15 hours 9 hours 18 hours 18 hours 14 minutes 36 minutes 10 hours 9.8 days 27 hours 4.2 days 4.2 days 160 days 22 minutes 8 hours 8-7 hours 10 minutes 9 1 hours 14 hours and 16 days 3 hours and 11 days 5.5 days and 14 hours 24 hours and 65 hours 12 days 5 minutes 3.3 hours 25 hours 85 minutes 6.7 days 85 minutes 18 hours Sensitivity after irradiation- n for 4 hours, CLg ? ? 0.03 7 22 18 50 0.02 0.08 30 0-4 1 2 0.8 0.4 0.8 ? ? ? 0-7 25 ? 5 1000 50 ? 0.2 120 50 ? ? ? 2 (1 ? ? 80 90 0.5 4 5 1 to saturation, Pg ? ? 0.03 0.07 17 0-2 0.02 0.08 0.3 0-3 1 0.1 0.2 0- 1 0.1 ? ? ? 0.1 0-3 ? 0.1 0.03 ? 0.06 22 20 30 50 ? ? ? 0.3 0-02 ? ? 80 50 0.06 4 0- 1 1 43 Interfering elements Ba Ba Ce __ - Ce, Ba Pr, Nd - sm Sm Eu, Gd Gd Yb, Dy Gd Ho Er Yb Tm, Yb Er 1x1, Hf Yb Hf Ta w Re 0 s Ir, Pt - - _- Pt CONCLUSIONS This method of analysis has most of the advantages of thermal-neutron radioactivatiori analysis.Often the sensitivity is not so great, but for .a few important light elements it is better with a flux of 1O1O neutrons per sq. cm per second. The sensitivity for half the elements in the periodic table is 1 pg or better; this would obviously be improved by increasing the neutron output of the accelerator. For the comparatively small capital outlay of about ,620,000 it should be possible to obtain a large and adequate flux of fast neutrons. REFERENCES 1. 2. Jenkins, E. N., and Smales, A. A., Quart. Rev., 1956, 10, 83. Atkins, D. H. F., and Smales, A. A., in EmelCus, H. J., and Sharpe, A. G., Editors, “Xdvances in Inorganic Chemistry and Radiochemistry,” Academic Press Inc., New York, Volume I, 1959, p. 315. 3. 4. De, A. K., and Meinke, W. W., Anal. Chern., 1958, 30, 1474. Coleman, R. F., and Perkin, J, L., Analyst, 1959, 84, 233.5. 6. 7. 8. 9. 10. 11. 12. 13. HASLAM, JEFFS AND WILLIS APPLICATIONS [Vol. 86 Turner, S. E., Anal. Chem., 1956, 28. 1457. Perkin, J. L., O’Connor, L. P., and Coleman, R. F., Proc. Phys. Soc., 1958,72, 505. Bronner, W. L., Ehlers, K. W., Eukel, W. W., Gordon, H. S., Marker, R. C., Voelker, F., and Fink, Gunnersen, E. M., and James, G., “Nuclear Instruments and Methods,’’ to be published. Coleman, R. F., and Perkin, J. L., Analyst, 1960, 85, 154. Hughes, D. J., and Schwartz, R. B., Brookhaven National Laboratory Report No. 325, Upton, Poularikas, A., and Fink, R. W., Phys. Rev., 1959, 115, 989. Wille, R. G., U S . Atomic Energy Commission Report AECU-4320, Fayetteville, Arkansas, 1959. Coleman, R. F., Hawker, B. E., O’Connor, L. P., and Perkin, J. L., Proc. Phys. Soc., 1959,73, 215 Received June 21st, 1960 R. W., Nucleonics, 1959, 17, 94. New York, 1958.

ISSN:0003-2654    

DOI:10.1039/AN9618600039

出版商:RSC    

年代:1961

数据来源: RSC