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11. |
The use of radioactive phosphorus in the study of phosphate separations |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 675-679
P. H. Bailey,
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摘要:
Dec., 19581 BAILEY AXD BROADBANK 675 The Use of Radioactive Phosphorus in the Study of Phosphate Separations BY P. H. BAILEY AND R. W. C. BROADBANK (School of Ciimkstty, College of Technology and Comnzevce, Lezcester) Phosphate ions containing radioactive phosphorus-32 have been used to study the efficiencies of three procedures for the removal of phosphate ions in semi-micro qualitative analysis. Small amounts of phosphate can be efficiently removed from solution by both the basic acetate and the metallic tin procedure. The zirconium nitrate procedure is also satisfactory, provided that an excess of reagent is avoided. When too much zirconium nitrate was present, separations were poor, owing to cloudiness, and Tolutions could not be clarified, even by prolonged centrifugation. TECHNIQUES involving radioactive nuclides are of considerable value in investigating analytical procedure, and can often give information about such things as co-precipitation, entrainment or completeness of precipitation.For example, radioactive phosphorus, azP, provides a particularly simple method of studying procedures for the removal of phosphate ions in qualitative analysis, since, provided that it is in the same chemical state as its inactive isotope, its radioactivity can be used as a measure of the concentration of the latter. Since the beta radiation of phosphorus-32 is fairly energetic (E,,,,, = 1.7 MeV), a liquid counter, such as that designed by Veal1,l can be used to measure the activity of labelled phosphate solutions and the comparatively long half-life (14 days) makes corrections for decay during an experiment unnecessary. PREPARATION OF RADIOACTIVE SOLUTIONS- Carrier-free phosphorus-32, as orthophosphate, in dilute hydrochloric acid can be obtained from the Radiochemical Centre, Amersham, and its metabolism and adsorption by micro- organisms may be prevented by means of an antiseptic.In this work, approximately 1 ml of a 10 per cent. phenol solution was immediately added when an ampoule was opened. Labelled phosphate solutions were prepared by adding a small amount of carrier-free radiophosphorus (approximately 0.05 to 0.1 microcurie) to standard solutions of calcium phosphate or potassium dihydrogen orthophosphate. EXPERIMEKTAL BASIC ACETATE PKOCEDURE- Two milligrams of calcium orthophosphate in 2 ml of dilute nitric acid were labelled with radioactive phosphate, and dilute hydrochloric acid was added to produce a solution approximately N with respect to that acid.Dilute ammonia was added until the solution was neutral to methyl red, and then 2 drops of acetic acid and 20 to 30 mg of solid ammonium acetate were added. Xeutralised ferric chloride solution was then added dropwise until the solution turned red, and the tube was set aside in hot water for about 10 minutes. After separation of the precipitate by centrifugation, the volume of the supernatant liquid was adjusted to 10 ml, and the solution was counted in a liquid counter (20th Century Electronics, type hI6H). The precipitate was dissolved in a little concentrated hydrochloric acid, the volume was adjusted to 10ml and the solution was counted in the same counter.After correction of readings for background and lost counts, the percentage of phosphate removed from solution was calculated. METALLIC TIN PROCEDURE- Two milligrams of calcium orthophosphate in 2 ml of dilute nitric acid were labelled with radioactive phosphate, and dilute hydrochloric acid was added to produce a solution approximately N with respect to that acid. Three to four millilitres of concentrated nitric acid and then 0.1 g of metallic tin were added. After the solution had been carefully evapo- rated to approximately 1 ml, 5 ml of distilled water were added, and the mixture was stirred and then spun in a centrifuge. The volume of the supernatant liquid was adjusted to 10 ml676 BAILEY AND BROADBANK: THE USE OF RADIOACTIVE [Vol.83 and the solution was counted. The residual stannic acid was dissolved in warm concentrated sulphuric acid, the volume was adjusted to 10 ml with this acid, and the solution was counted. Readings were corrected for background, lost counts and the density of concentrated sulphuric acid, and the percentage of phosphate removed from solution was calculated, ZIRCONIUM NITRATE PROCEDURE- Owing to the low efficiencies initially found when this method was used, a much more extensive series of investigations was carried out, Different volumes and concentrations of phosphate solutions (usually potassium di- hydrogen orthophosphate) were labelled with radioactive phosphate, and hydrochloric acid was added to produce a solution 0.9 N with respect to that acid.Definite amounts of zirconium nitrate reagent solution2 were added slowly, and the solution was set aside in the cold for a few minutes. The precipitated zirconium phosphate was separated by centrifuga- tion, and the supernatant liquid was adjusted to a suitable volume and then counted. The precipitate was dissolved in concentrated sulphuric acid, adjusted to the same volume with that acid and then counted. Readings were corrected for background, lost counts and the density of concentrated sulphuric acid, and the percentage of phosphate removed from solution was calculated. The same procedure was used to study the (effects of other ions on the efficiency of the separation, various added salts also being present in the solution of potassium dihydrogen orthophosphate. CORRECTIOX FOR DENSITY OF SULPHURIC ACID-- centrated sulphuric acid, respectively. of the counting rates was used as a correction factor.Equal amounts of radioactive phosphate were made up to 10ml with water and con- The two solutions were then counted, and the ratio CALCULATION o F RESULTS The method used to calculate the efficiency of separation is shown by the evaluation of the following set of experimental results for the zirconium nitrate procedure- Volume of solution, ml . . . . . . . . . . Weight of potassium dihydrogen orthophosphate present, Amount of zirconium nitrate reagent solution used, drops Activity of supernatant liquid, counts per minute . . Activity of precipitate, counts per minute . . . . Background activity, counts per minute .. . . Paralysis-time of counting assembly, microseconds Correction factor for density of sulphuric acid . . . . . . . . = 4 mg . . = 20 . . . . = 12 . . . . = 121 * 2 . . . . = 8715 66 . . . . = 17 & 1 . . . . = 300 . . . . = 1.6 (The standard deviation for the counting rates, N counts being recorded in t minutes, has been taken as l / t x A'&.) Counting rate for precipitate (corrected for lost counts), counts per - 8715 x 60 . . . . . . . . . . . . , . . . - 60 - (8715 x 3 x 10-4) minute . . = 9100 & 67 . . . . . . . . . . . . . . = 9083 f 67 Counting rate for precipitate (corrected for background), counts per Counting rate for precipitate (corrected for density of sulphuric acid), minute . . . . counts per minute .. . . . . . . . . . . . . = 9083 & 67 x 1.6 = 14,533 i 108 Counting rate for supernatant liquid (corrected for background), counts per minute . . . . . . . . . . . . . . = 104 i 2 - 14,533 x 100 = 99.3 . . 14,533 + 104 -4ctivity removed from solution, per cent. . . . . . . - This, of course, is the efficiency of the separation. Owing to the low counting rates for the supernatant liquid and the background, the 108 x 100 x 4 2 . , z.e., 14,637 All standard standard deviation of the percentage efficiency i'j approximately 5 I 1 per cent. deviations were of the order of & 1 per cent. The efficiency of separation is therefore 99.3 5 1 per cent.Dec., 19581 PHOSPHORUS IN THE STUDY OF PHOSPHATE SEPARATIONS 677 RESULTS Two experiments were carried out on both the basic acetate and the metallic tin pro- The efficiencies 1 per cent., 99.5 i 1 per cent.and 99.4 i 1 The results of experiments on the zirconium nitrate procedure are cedures, 2 mg of calcium orthophosphate being present in each instance. of separation were 97.9 per cent., respectively. shown in Figs. 1, 2 , 3 and 4. 1 per cent., 98.8 l i x >; C W ._ g I 6ot I 1 1 , I I 20 4] / Amount of phosphate, as PO,]., mg Efficiency of separating phosphate ions from lOml of solution with 12 drops of zirconium nitrate reagent solution Fig. 1. 90 I00 1 / 7 4 i Ib 1; 210 -is io 15 Concentration of phosphate ion, rng per 10 rnl Fig. 3. Efficiency of separating phosphate ions from solution a t different ratios of phosphate ion to zirconium nitrate reagent solution: curve A, 0.875 mg of phosphate ion per drop of reagent solution; curve B, 1.17 mg of phosphate ion per drop of reagent solu- tion; curve C, 0.58mg of phosphate ion per drop of reagent solution C M .P E 0.2 .* Initial concentration of phosphate ion, mg per 10 ml Amount of phosphate remain- ing in lOml of solution after separation at a ratio of 0475 mg of phosphate ion per drop of zirconium nitrate reagent solution Fig. 4. DISCUSSION OF RESULTS I N ABSENCE OF ADDED SALTS- It can be seen from Fig. 1 that removal of phosphate ions by the zirconium nitrate method is not maintained at optimum efficiency simply by ensuring that excess of zirconium nitrate is present. Cloudy solutions, which could not be clarified even by centrifuging for 30 minutes, were invariably obtained when too much reagent was added.This was presumably caused by colloid formation and was responsible for the low efficiencies under these conditions. This is further shown by Fig. 2, from which it can be seen that 3.5 mg of phosphate can be removed with optimum efficiency from 10 ml of solution by adding 4 drops only of zir- conium nitrate reagent solution. With larger amounts of phosphate there is more latitude, excellent separation of 15.5 mg of phosphate being obtained with 14 to 18 drops of reagent solution.678 BAILEY AND BROADBANK: T.KE USE OF RADIOACTIVE [Vol. 83 I t is interesting to note that the ratio of phosphate ion per 10ml of solution to the number of drops of zirconium nitrate reagent solution required for optimum efficiency is approximately constant ; this is shown by the following results- .\mount of phosphate ion present, mg per 10 ml .. . . . . 3.5 10.5 l5.g Amount of zirconium nitrate reagent solution needed for maximum ;\mount of phosphate ion equivalent to 1 drop of reagent solutioti, mg efficiency, drops.. . . . . . . . . . . . . . . 4 12 14 to 18 0.875 0.875 0.86 t o 1.1 I Provided that this ratio is maintained, the zirconium nitrate method for phosphate separation gives satisfactory results over a wide range of phosphate concentrations (see Fig. 3, curve A) and leaves in solution only about 0.15 mg of phosphate ion per 10 ml (see Fig. 4). A further point of interest is that smaller amounts of zirconium nitrate than those indi- cated by the optimum ratio give much better separations than larger amounts. For example, a t a ratio of 0.875 mg of phosphate per drop of reagent, 15.5 mg of phosphate would require 17.76 drops of zirconium nitrate reagent solution. A further very small amount of reagent may be added for satisfactory separation, but as little as 14 drops will give excellent results (see Fig.2 ) . This is more clearly shown by Fig. 3, in which curve B is that for 1.17 mg of phosphate per drop of reagent solution and curve C that for 0 5 m g per drop. The latter conditions give cloudy solutions and did not provide a satisfactory separation a t any of the phosphate ion concentrations investigated. On the other hand, provided that the phosphate concentration does not fall below approximately 17 mg per 10 ml, the former conditions provide a separation indistinguishable from the optimum (curve A).A possible explanation is that the zirconium phosphate precipitate itself functions as a scavenger for phosphate ions. In order to express the optimum ratio as phosphate ions per atom of zirconium, 12 drops of zirconium nitrate reagent solution were evaporated on platinum foil, and, on ignition, were found to give 20.0 mg of zirconium oxide. This corresponds to 1.23 mg of zirconium per drop, from which it can be calculated that the optimum reagent to phosphate ratio is almost exactly three zirconium atoms to two phosphate ions. This may be compared with Pittman’s recommendation3 of 35 ml of 0.015 M zirconyl chloride for each 40 mg of phosphate, i . e . , five zirconium atoms to four phosphate ions, which is equivalent to 15 drops of zirconium nitrate reagent solution per 15.5 mg of phosphate.This would give a satisfactory separation (see Fig. 2), although the amount of reagent is less than that corresponding to our optimum volume. EFFECTS OF CERTAIN ADDED IONS- A series of experiments with 3.5 mg of phosphate ion per 10 ml of solution in the presence of 5 mg each of ferric nitrate, cobalt chloride, strontium nitrate and sodium chloride gave results similar to those shown by curve A of Fig. 2 . However, when sodium chloride was replaced by sodium tartrate (which will, under suitable conditions, produce a precipitate with zirconium nitrate) the curves shown in Fig. 5 were obtained. These curves are similar to those of Fig. 2 , but the optimum amounts of ziirconium nitrate solution are 6 drops instead of 4 and 17 to 24 drops instead of 14 to 18.It appears, therefore, that the phosphate and tartrate ions are competing for the zirconium reagent. I t may be noted, incidentally, that the amount of reagent recommended by Pittman is no longer sufficient to give a phosphate separation of optimum efficiency. Zirconium nitrate solution will often give a precipitate in the presence of a large excess of potassium sulphate. A series of experiments was therefore carried out with 3.5mg of phosphate ion and 20mg of potassium sulphate, together with other salts, per 10ml of solution. The results are shown in Fig. 6, from which it can be seen that the optimum amount of reagent is again 4 drops, as in Fig. 2, but the efficiency of separation decreases much less rapidly as excess of zirconium nitrate is added.CONCLUSIONS From the limited number of determinations (carried out, it appears that small amounts of phosphate can be efficiently removed from solution in semi-micro qualitative analysis by either the basic acetate or the metallic tin method. A more comprehensive series of experiments indicates that the zirconium nitrate method can also give excellent separations, provided that an excess of reagent is avoided. From this point of view, the recommendationsDec., 19581 PHOSPHORUS I N THE STUDY OF PHOSPHATE SEPARATIONS 679 in a recently published scheme for semi-micro qualitative analysis4 are excellent-“. . . add zirconium nitrate reagent drop by drop until precipitation is complete. Only a small excess of reagent should be present and it is preferable to add it a few drops at a time, centrifuging after each addition.” Drops of zirconium nitrate reagent solution added Fig. 6. Effect of the presence of 5 mg each OO of ferric nitrate, cobalt chloride, strontium ni- Fig. 5. Effect of the presence of 5 mg each trate and sodium chlor- of ferric nitrate, cobalt chloride, strontium nitrate ide and 20mg of and sodium tartrate on the efficiency of separ- potassium sulphate on ating phosphate ion from 10 ml of solution: curve the efficiency of separ- A, 3.5 mg of phosphate ion; curve B, 15.5 mg of ating3.5mgofphosphate phosphate ion ion from lOmlofsolution 2oy; Ib I; ~o ~5 jo Drops of zirconium nitrate reagent solution added REFEREKCES 1. Veall, X., Brit. J . Radiol., 1948, 21, 347. 2. lrogel, A. I., “A Textbook of Macro and Semi-micro Qualitative Inorganic Analysis,” Fourth 3. Pittman, F. K., Ind. Eng. Chew., Anal. Ed., 1940, 12, 514. 4. The Midlands Qualitative Inorganic Analysis Committee, “Semi-micro Qualitative Inorganic Received April 23rd, 1958 Edition, Longmans, Green h Co. Ltd., London, 1954, p. 639. Analysis,” Stanford h Mann Ltd., Birmingham, 1957, p. 35.
ISSN:0003-2654
DOI:10.1039/AN9588300675
出版商:RSC
年代:1958
数据来源: RSC
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12. |
The transmission characteristics of some interference filters for use in flame photometry |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 679-683
R. D. Bond,
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PDF (355KB)
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摘要:
Dec., 19581 PHOSPHORUS I N THE STUDY OF PHOSPHATE SEPARATIONS 679 The Transmission Characteristics of some Interference Filters for use in Flame Photometry BY R. D. BOND AND H. C. T. STACE (C.S.I.R.O., Division of Soils, Adelaide, South Austvalia) The transmission characteristics of seven combination interference- absorption filters and one gelatin absorption filter for the isolation of the sodium D line have been determined. The filters have been examined for errors caused in the flame-photometric determination of sodium by radiation emitted by other elements a t wavelengths within incompletely suppressed transmission bands. IN recent years, interference filters of the metal - dielectric type have to some extent replaced absorption or colour filters for isolating characteristic radiations in the determination of elements by flame photometry.For the isolation of many radiations, these interference filters can be produced with a narrower transmission band and higher maximum transmittance than the best absorption filters. Such characteristics make interference filters suitable for use in flame photometry. However, for the efficient use of these filters, it is essential that other aspects of their transmission characteristics be appreciated.680 BOND AND STACE : TRANSMISSION CHARACTERISTICS OF SOME [Vol. 83 Normally, interference filters transmit several orders of frequencies or wavelengths, which are integral multiples of some fundament a1 frequency; the frequencies at which the transmission maxima occur are determined by the structural characteristics of the filter.They also show some transmittance between these maxima, and this “background,” as it is termed, is usually somewhat less than 1 per cent. Under ideal operating conditions, the maximum transmittance at the required wavelength may be as high as 50 to 60 per cent. The general transmission characteristics of a typical interference filter have been discussed by Green1and.l For the effective use of interference filters in flame photometry, the unwanted trans- mission bands and the “background” transmission must be suppressed, which is usually done by auxiliary filters, e.g., suitable absorption filters. Experience with some commercial interference-absorption filters has shown that the unwanted bands have not always been completely removed and that radiations emitted within the wavelength range of these bands may cause serious errors in some determinations.The transmission characteristics of seven combination interference-absorption filters, which are commercially available for the isolation of the sodium doublet at 5890 and 5896 A, have been determined. The filters were also examined in an E.E.L. flame photometer (Evans Electroselenium Ltd.) to measure the interference caused by radiations emitted by other elements during the determination of sodium in soil extracts, minerals, rocks and similar materials. TRANSMISSION CHARACTERISTICS The transmission characteristics of the filtjers were determined with a Beckman DU spectrophotometer at a slit width of approximately 0.1 mm; the salient features of each filter are shown in Table I.The values for the various Characteristics were found to differ somewhat over the surface of the filter, e.g., for filter B, the maximum transmittance of the sodium D line varied from 20 to 30 per cent. and the wavelength of maximum transmittance from 5820 to 5 8 6 0 ~ ; the values shown in Table I are for a central portion of the filter. Filters A, B, C, D and E were of Scottish manufacture and were supplied as approximately identical filters for the isolation of the sodium doublet. Filters F and G were of German origin and were described as a precision double-line-filter and a double-line-filter, respectively. Filter H was a standard gelatin absorption filter supplied with the E.E.L. flame photometer for the isolation of the sodium doublet; this filter was included for comparison.The full transmission curves for filters E, F and H are shown in Fig. l(a). Of the two filters E and F, E transmits no radiations below 5450 A. It does, however, show another peak at 8 6 4 0 ~ and has minimum transmittance (0.4 per cent.) between the peaks. The absorption filter in this combination cuts out only those radiations below 5450 A. Filters A, B, C and D showed transmission characteristics similar to filter E. Filter F, on the other hand, transmits no radiation below 5650 A or above 6500 A. The absorption filter incor- porated in F cuts out all radiations below and above these wavelengths. Also, it is noteworthy that filter F has a narrower transmission band than filter E. Filter G was somewhat similar to F in that there was no other transmission peak at longer wavelengths; however, there was a small amount of background transmittance at wavelengths longer than 6500 A. The gelatin absorption filter, H, does not completely cut off the longer wavelengths and has a marked increase in transmittance at 8500 A.INTERFERENCES IN THE DETERMINATION OF SODIUM In the flame-photometric determination of sodium, many other elements and compounds may be present, some of which, e g . , lithium, potassium, rubidium, caesium and calcium oxide, emit radiations in the wavelength range 5500 to 9000 A. The positions of these radiations are shown in Fig. 1 (b). It can be seen that filters E and H transmit different proportions of these radiations. When these elements are present in samples from which the sodium radiation is to be isolated, some interference can be expected.Filter F, on the other hand, does not transmit any of the radiations from lithium, potassium, rubidium and caesium, and interference from these elements should be negligible. I t does, however, transmit a small proportion of the radiation from calcium oxide, and some interference from any calcium present in the sample is to lbe expected. However, because its trans- mittance at this wavelength is only a small fraction of that of the other two filters (see Fig. l), this error should be correspondingly smaller.TABLE I TRANSMISSION CHARACTERISTICS OF THE FILTERS Peak at sodium D f L Band width at Wavelength 50 per cent. Wavelength Maximum of maximum of maximum of zero Trans- trans- trans- trans- trans- mittance Filter mittance, mittance, mittance, mittance, at 6100 A, % A A A YO A 17 5900 90 5600 0-8 B 26 5850 150 5400 3 C 35 5860 150 5400 3.5 D 28 5840 160 5400 3 E 34 5900 200 5450 6 F 28 5905 90 5650 0.6 G 24 5880 100 5650 0-2 H 9.5 5850 - 5250 3 Trans- mittance a t 6500 A, % 0- 1 0.8 0.6 0.4 0.8 < 0-01 0-05 0.3 Trans- mittance at 7000 A.0.05 0.5 0.4 0.2 0.4 < 0.01 0.05 0.15 % v Trans- mittance at 8000 A, 0.15 0.6 1.0 0.8 0.8 < 0-01 0.05 0.45 YO 7- Maximum trans- mittance, 14 19 30 22 29 % - - - Second peak* Band width a t Wavclcngth 50 per ccnt. of maximum of maximum trans- trans- mittance, mittance, A A 8580 100 8550 200 8520 180 8530 200 8640 200 * No second peak was detected for filters F and G.TABLE I1 APPARENT AMOUNTS OF SODIUM DETERMINED IN VARIOUS SOLUTIONS BY USING DIFFERENT FILTERS Each solution contained 20 milli-equivalents of solute per litre. The corrected results have been adjusted for the presence of sodium as impurity in the reagents Lithium chloride solution Potassium nitrate solution 7- - Uncorrected Corrected Uncorrected Corrected amount of amount of amount of amount of sodium found, sodium found, sodium found, sodium found, milli- milli- milli- milli- equivalents equivalents equivalents equivalents Filter per litre per litre per litre per litre A 0-022 B 0.027 C 0-025 D 0.022 E 0.020 F 0.008 G 0.012 H 0.018 0.014 0.019 0.017 0-014 0.012 Nil 0-004 0010 0.008 0.004 0.026 0.022 0.023 0.019 0.020 0-016 0.01 1 0-007 0.004 Nil 0.007 0.003 0.007 0.003 Rubidium chloridc solution v-7 Uncorrected Corrected amount of amount of sodium found, sodium found, milli- milli- equivalents equivalents per litre per litre 0.023 0.007 0.041 0.025 0.040 0.024 0.036 0.020 0.025 0.009 0-016 Nil 0-019 0.003 0.029 0.013 Caesium chloride solution ---7 Uncorrected Corrected amount of amount of sodium found, sodium found, milli- milli- equivalents equivalents per litre per litre 0.058 0.026 0.064 0.032 0.068 0.036 0.065 0.033 0.054 0.022 0.032 Nil 0.034 0.002 0.074 0.042 Calcium chloride solution ~ __ -.-L7 Uncorrected Corrected amount of amount of sodium found, sodium found, milli- milli- equivalents equivalents per litre per litre 0.050 0.050 0.132 0.132 0.121 0.121 0.109 0.109 0.114 0.114 0.033 0.033 0.039 0.039 0.133 0.133682 BOKD AND STACE: TRANSMISSION CHARACTERISTICS OF SOME [Vol.83 In order to determine the magnitude of these expected interferences, solutions containing 20 milli-equivalents per litre of lithium, potassium, rubidium, caesium and calcium were prepared. As lithium and sodium chlorides recrystallise from water together, analytical- reagent grade lithium chloride may contain up to 0.3 per cent. of sodium chloride. Sodium chloride is, however, almost insoluble in n-butyl alcohol, lithium chloride being soluble to the extent of 11 per cent. A purified sample clf lithium chloride was therefore prepared by forming a saturated solution in n-butyl alcohol in the presence of an excess of lithium chloride, spinning in a centrifuge and evaporating the supernatant liquid in a platinum dish.The residue was dissolved in water. the chloride was determined bv titration, and the volume was adjusted to give the required concentration. 30 x .- 0 20 5 i .4 .- c 10 0 5250 6000 7000 8000 91 Wavelength, A I0 Wavelength, A Fig. l ( a ) . Transmission curves of filters E, F and:H Enlargemcnt of (a) from 0 to 0.5 per cent. transmission Fig. l(b). Potassium nitrate, which had been recrystallised and was known to be low in sodium, was used in preference to analytical-reagent grade potassium chloride. From our experience, nitrate in place of chloride at the concentration used has no significant effect on readings with the E.E.L. flame photometer. The solutions of rubidium and caesium were prepared by dissolving the appropriate amounts of the chlorides in water.The calcium chloride was prepared by dissolving calcium carbonate (of the quality used in the Lawrence-Smith method for determining alkalis) in a slight excess of hydrochloric acid. Sodium chloride solutions of various concentrations in the range 0 to 0.2 milli-equivalent per litre were used to prepare a calibration curve, and the amounts of apparent sodium in the test solutions (all 0.02N) were determined; the results are shown in Table 11. DISCCSSION OF RESULTS Each filter was examined in turn. Each result for apparent sodium in Table 11 may be the sum of any one or more of (a) An increase in the background radiation at the wavelengths of sodium (5890 and 5 8 9 6 ~ ) caused by the use of concentrated solutions. ( b ) Radiation from sodium as impurity in the compounds.(c) Radiation from other elements, which is emitted at wavelengths in the vicinity of the sodium doublet or within other transmission bands that have been incompletely suppressed by the auxiliary filters. three components-Dec., 19581 INTERFERENCE FILTERS FOR USE IS FLAME PHOTOMETRY 683 BACKGROUND RADIATION, AXD SODIUM AS IMPURITY- The amount of radiation from lithium, potassium, rubidium and caesium transmitted by filter F (see Fig. 1) is negligible, and results for apparent sodium (see Table 11) found with use of this filter for compounds of these elements can be considered to arise from components (a) and ( b ) . In order to determine the magnitude of component ( a ) , an E.E.L. atomiser-burner was set up in conjunction with a Beckman DU spectrophotometer, and the instrument was cali- brated at a slit width of 0.15 mm with a solution containing 1.0 milli-equivalent of sodium per litre.The wavelength scale was then altered (by about 50 -4) below sodium 5890 and 5896 A until the transmission scale of the instrument showed for the sodium solution a reading equal to that for distilled water. Each test solution was then atoniised, and its background value was determined. For the solutions of lithium, potassium, rubidium and caesium, no increase over the original background value was detected. The results were similar at a wavelength reading above the sodium line. Component (a), therefore, did not contribute to the apparent sodium values for compounds of these elements. For calcium, however, the background value varied with the slit width, i.e., some radiation from this element was measurable a t sodium 5890 and 5896 A.From these considerations, it was concluded that the apparent sodium 1-alue found for solutions of lithium, potassium, rubidium and caesium when filter F was used were caused by sodium as impurity in the reagents. This was supported by the apparent sodium values for the lithium chloride solution before and after purification, which were 0.047 and 0.008 milli-equivalent per litre, respectively. As the calcium solution was prepared from calcium carbonate that was extremely low in sodium, it is considered that the apparent sodium value found was due to insufficient selectivity of the filters (see Fig. l), which thus transmitted some radiation from the calcium oxide molecule.Table I1 also shows apparent sodium values that have been corrected for the sodium present as impurity. RADIATIOK FROM OTHER ELEMENTS- It is considered that the corrected apparent sodium values in Table I1 are caused solely by radiation emitted by the particular element under investigation a t wavelengths in the vicinity of the sodium line or within other transmission bands that have been incompletely suppressed. If this is so, the apparent sodium values found for a particular solution with different filters should be approximately proportional to the ratio of the percentage transmission a t the wavelength of emission to the percentage transmission at the sodium line. For example, the transmittance of filter E is 34 per cent.a t the sodium line and 0.6 per cent. at the lithium line; i.e., the transmittance a t the lithium line is 1.8 per cent. of that at the sodium line. For filter H, the transmittance at the lithium line is 1.1 per cent. of that a t the sodium line. The error for filter E should therefore be 1.6 times that for filter H. The error in practice is found to be 1.2 times as great, which is satisfactory agreement when it is considered that the transmission characteristics were measured over only a small area of the filter and that variation can occur over the surface of the filter. When comparing the relative importance of the different elements in any determination, photocell response must be considered. The response of the selenium cell used in the E.E.L. flame photometer decreases at longer wavelengths, and hence the effect of the increase in transmittance of the gelatin filter and the second peaks of some of the interference filters is somewhat ofiset. However, for instruments in which the newer infra-red sensitive photo- cells are used, these increases in transmittance could cause greater errors than those reported here. Although it may be considered that the magnitude of this type of interference is insig- nificant in many determinations, it could assume serious proportions in some analyses, e g . , the determination of small amounts of sodium in minerals composed largely of the elements considered here. I t is therefore essential that the full transmission characteristics of filters used in flame photometers be known, so that precautions can be taken to overcome interferences caused by the transmission of radiation at incompletely suppressed wavelengths. REFERENCE 1 . Greenland, I<, M., Endeavour, 1962, 11, 143. Received June Qth, 1958
ISSN:0003-2654
DOI:10.1039/AN9588300679
出版商:RSC
年代:1958
数据来源: RSC
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13. |
Notes |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 684-699
R. D. Bond,
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PDF (1147KB)
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摘要:
684 NOTES [Vol. 83 Notes THE USE OF SULPHURIC ACID TO DEPRESS THE INTERFERENCE OF CALCIUM IN THE DETERMINATION OF SODIUM WITH AN E.E.L. FLAME PHOTOMETER THE E.E.L. flame photometer (Evans Electroseleniunn Ltd.) makes use of coal gas and air to give a relatively low-temperature flame, and absorption filters are used to isolate the appropriate radiations1 Under these conditions, some of the radiation from calcium oxide bands may pass through the filter and cause considerable error in the determination of sodium. This error can be reduced by using a more selective filter that trmsmits less of the calcium oxide radiation and also by decreasing the intensity of the calcium emission. Certain interference filters, which have maximum transmission a t 5890 A, transmit less calcium oxide radiation than does the gelatin filter supplied with the instrument, and use of such fiilters reduces the calcium interference.The complete transmission characteristics of an interference filter must be known, however, before it can be used safely.2 A coal gas - air flame supplies insufficient energy to volatilise all calcium salts to the same extent, and this property can be used to reduce the: interference further. The well known de- pressive effect of phosphate on the emission of calcium in such a flame is largely due to the lower volatility and dissociation of calcium phosphate? ,4 ,5 When added to solutions of calcium chloride, sulphates also depress calcium emission. Although this depression is less than that caused by phos- phates, it is of greater analytical significance in controlling the error caused by calcium in the deter- mination of sodium, for it can be made constant a t any given calcium level.The depression caused by phosphate is not constant; it depends on (other anions present, and emission is partly restored by sulphate. In the presence of a sufficient amount of sulphate, however, calcium emission is independent of other anions naturally present and is determined solely by the calcium level. EXPERIMENTAL To measure the depression in calcium emission caused by adding sulphate, the “calcium” interference filter supplied with an E.E.L. flame photometer was placed in position, and the instrument was adjusted to give a galvanometer reading of 100 with a solution of calcium chloride containing 1.00 milli-equivalent of calcium per litre.The scale readings for solutions of calcium chloride with different amounts of sulphuric acid were then determined ; the results are shown in Table I. TABLE I EFFECT OF SULPHATE AND PHOSPHP,TE ON CALCIUM EMISSION Calcium chloride present, milli- equivalents per litre 1.00 1.00 1.00 1.00 1.00 0.50 0.50 0.50 1.00 1.00 1.00 1.00 1.00 - - - - - - - - Calcium sulphate present, milli- equivalents per litre - - - - - - - - - - - - - 1.00 1.00 1.00 1-00 1.00 1.00 1.00 1-00 Potassium dihydrogen phosphate present, milli- equivalents per litre - - - - - - - - - - 1.00 1.00 1.00 - - 1.00 1.00 - - - - Potassium chloride present, milli- equivalents per litre - - - - - - - - - - - - - - - - - 1.00 1.00 5.00 5.00 Orthophos- phoric acid present, milli- equivalents per litre - - - - - - - - 1.00 1.00 - - - - 1.00 - - 1.00 1.00 1.00 1.00 Sulphuric acid present, milli- equivalents per litre 0.30 0.60 1.00 5.00 0.30 0.50 1.00 1.00 2.00 - - - - - - - 1.00 1.00 1.00 5.00 - Galvano- meter reading 100 83 71 65 64 50 35 32 19 63 20 39 63 65 61 31 61 23 62 58 65Dec., 19381 NOTES 685 I t can be seen that the calcium emission is progressively decreased until the amount of sulphuric acid added is equivalent to the amount of calcium present, after which further additions of sulphuric acid are without effect.This implies that, when a small excess of sulphuric acid is present in the determination of sodium, not only is the error caused by extraneous calcium emission reduced by approximately one-third a t any given level of calcium, but it is reduced to a constant value for that level.The interaction of sulphate and phosphate on calcium emission in the presence of other salts was also studied, the same interference filter being used. From the results, which are also shown in Table I , it can be seen that, although phosphate reduces calcium emission much more markedly than does sulphate, in the presence of both phosphate and sulphate, the emission is suppressed to a lesser extent depending on the amount of phosphate that remains combined with other metal ions. When phosphate is present and the amount of sulphuric acid used is slightly in excess of that equivalent to the calcium and other metal ions, the calcium radiation corresponds almost exactly to that of a pure calcium sulphate solution of equivalent concentration.To confirm that the error caused by calcium in the determination of sodium can be controlled by reducing and stabilising calcium radiation in the vicinity of the sodium doublet, the radiation transmitted by “sodium” filters of both gelatin and interference types was measured. The solutions used and the results obtained are shown in Table 11. TABLE I1 EFFECT OF CALCIUhl AND SULPHURIC ACID ON THE DETERMINATION O F SODIUM Calcium chloride present, milli- equivalents per litre 2.00 5.00 10.00 2.00 2.00 5.00 5.00 10.00 2.00 5.00 10.00 2.00 5.00 5.00 10.00 Sulphuric acid prescnt, milli- equivalents per litre - - - 1.00 2.00 1.00 5.00 10.00 - - - 2.00 5.00 1.00 10.00 Sodium chloride present, milli- equivalents per litre - - - - - - - - 0.100 0.100 0.100 0.100 0.100 0.100 0’100 Galvano- meter reading with gelatin filter (H) 7 18 36 4 16 10 17 63 74 91 60 65 72 72 0 Galvano- meter reading with interference filter (A) 3 8 15 3 2 7 4 8 61 64 70 58 61 63 63 Increase in sodium with filter H, micro- equivalents per litre 12 34 66 10 8 30 18 31 17 40 80 12 22 36 37 Increase in sodium with filter A, micro- equivalents per litre 5 13 26 4 3 12 7 13 8 16 30 4 8 14 14 The characteristics of the filters H and A have been determined by Bond and Stace.2 The apparent amounts of sodium found in the sodium-free solution (caused by extraneous calcium emission) and the amounts in excess of those known to be present in the other solutions are shown in the last two columns of Table 11.I t can be seen that, when an amount of sulphate equivalent to the calcium present has been added, the error is less than in the absence of sufficient sulphate and also that the error is less with interference filter A than with gelatin filter H.COh-CLUSIONS In the determination of sodium in dilute solutions containing calcium by means of an E.E.L. flame photometer, a small excess of sulphuric acid should be added to stabilise and reduce calcium emission. The amount of sulphuric acid should be a t least equivalent to the amount of calcium present, and, if the solution contains anions, such as phosphate or bicarbonate, an additional amount of sulphuric acid equivalent to any other metal ions present should be added. Under these conditions, with a given filter, calcium radiation can be determined (as shown by the results in Table 11) and a suitable correction can be applied to the sodium value if, as often happens, the amount of calcium present is known.In dilute solutions, this correction is essentially independent of the amount of sodium present, but this is not so for, say, the 0.2 A’ ammonium chloride commonly used in soil analysis. \\’ith such solutioris it was found that, when interference filter A was used, the correction increased from 0.01 niilli-equivalent of sodium per litre for each 10 milli-equivalents of calcium in the absence656 NOTES [Vol. 53 of sodium, t o 0.02 milli-equivalent of sodium per litre for the same amount of calcium in the presence of 0.10 milli-equivalent of sodium per litre. REFERENCES 1. 2.3. 4. 5 . Collins, G. C., and Polkinghorne, H., Analyst, 1952, 77, 430. Bond, R. L)., and Stace, H. C. T., Ibid., 1958, 83, 679. Margoshes, lI., and T’allee, B. L., Anal. Chew., 1956, 28, 180. Scharrer, K., and Jung, J., Z. Pj’lEvnlihr. Dung., 1954, 67, 240. Stace, H. C. T., and Hutton, J . T., “Flame Excitation Methods of Spectrochemical Analysis,” C.S.I.R.O., Melbourne, 1958. C.S.I.R.O., DIVISIOX OF SOILS R. L). BOND ADELAIDE, SOU’TH AUSTRALIA J . T. HUTTON Received June 9th. 1958 -4 RE‘4CTION BETWEEN nzesoINOSIT0L AND URANYL ACETATE EXISTIXG chemical methods for the detection and determination of inositol depend on its reducing power as a polyhydroxy compound. A reaction has been observed between mesoinositol and uranyl acetate solutions, which may provide the basis for a rnethod of detection on paper chromatogramsl and for determination in solution after chromatographic separation from other polyols.2 QUALITATIVE TEST ox PAPER CHROMATOGRAMS The chromatogram is sprayed lightly with a 2 per cent.aqueous solution of uraiiyl acetate The presence of inositol is indicated The normal fluorescence of uranyl acetate Of possible interfering substances tested, only glycerol was found t o react, and then only in There has been no opportunity t o test the isomeric and is immediately examined under ultra-violet illumination. by a green fluorescence against a colourless background. is completely suppressed by the paper. milligram amounts. inositols. Sugars do not react. Inositol monophosphate reacts only faintly. REACTION I N SOLUTION By contrast, in aqueous solution (pH 4.4), the large blank fluorescence of uranyl acetate is only feebly enhanced by addition of inositol.When increasing amounts of sodium hydroxide are added, the enhancement of fluorescence caused by inositol is decreased t o the point where the effect of inositol is reversed and quenching occurs. This quenching effect is of much greater magnitude than the enhancement and is more suitable for measurement. There would appear t o be no theoretical limit to the sensitivity, but, in practice, as the sensitivity increases the accuracy decreases. A tentative method, in which the quenching effect is used, has been established for the determination of iuositol eluted from paper chromatograms. Standard curves are completely reproducible in the range 20 to 200 pg, but the main difficulty has been the variable blanli values found from the paper strips.Inositol was completely extracted from the paper into uranyl acetate solution in 1 hour, and the degree of quenching of the fluorescence was constant 2 hours after the alkali had been added. At p H 4.4, addition of inositol t o uranyl acetate solution has little effect on the pH, but enhances the fluorescence. At pH 6.0, addition of inositol causes quenching of the fluorescence, and the solution becomes more alkaline. This increase in pH was directly proportional t o the amount of added inositol, but was of small magnitude (0.27 p H units per 0.1 mg of inositol). The yellow complex formed by the reaction of mesoinositol with uranyl acetate a t pH 4.4 showed an apparent absorption curve with peaks at 356, 315 and 240 m p when a single mono- chromator instrument was used.However, the sensitivity attainable by absorptiometry a t these peaks does not approach that of the fluorimetric quenching method. The formation of coloured complexes between the uranyl ion and polyhydroxy compounds has been noted previously? Quenching of fluorescence by polyhydrory compounds has been noted by M’est.3 Two other aspects of the reaction are worth mentioning. REFERENC:ES I . 2. 3. West, IV., “Physical Methods in Organic Chemistry,” Second Edition, Interscience Publishers Hawthorne, J . N., Biochim. Biophys. Acta, 1955, 18, 391. Meredith, P., and Sammons, H. G., Analyst, 1952, 77, 416. Inc., Kew York, 1949, Volume I, p. 1441.Rodden, C. J., and Warf, J . C., National Suclear Energy Series, Division VIII, “Analytical Chemistrv of the Manhattan Proiect,” McGraw-Hill Book Co. Inc.. New York, 1960. Volume I. 4. p. 12, refkrences 59 and 60 (orighals not seen) DEPARTMENT OF MEDICAL BIOCHEMISTRY AND PHARMACOLOGY UNIVERSITY OF BIRMINGHA~~ P. MEREDITH H. G. SAXMONS Received July 3rd, 1958Dec., 19583 SOTES THE DETERMINATION OF ETHYLENE DIBROMIDE IK BRINE 687 THE methods generally used for determining halogens in organic compounds, such as the sodium fusion methodl and the Carius and other combustion methods,2,3,4*5 can be applied to the deter- mination of ethylene dibromide. However, a more simple procedure especially adapted to simple aliphatic alkyl halides involves alkali hydrolysis and subsequent determination of the liberated bromide.Kennetts described a method for determining ethylene dibromide and ethylene chlorobromide in air. An ethanolic solution of these halides, prepared by shaking the sample of air with ethanol, is heated under reflux in the presence of sodium hydroxide for 15 minutes, and, after acidification with nitric acid, the bromide is determined argentimetrically by Volhard's method. The proposed method is based on the extraction of ethylene dibromide from the brine obtained during process development for the manufacture of ethylene dibromide from ethylene and bromine, the latter being liberated in situ from bromide with chlorine gas. The extraction is carried out with xylene, and the extract is then heated with potassium hydroxide in the presence of 92-butyl alcohol, which serves as a mutual solvent for the xylene and the alkali. The liberated bromide is determined gravimetrically as the silver salt.METHOD REAGENTS- Xylene-Technical grade. n-Butyl alcohol-The reagent free from halides. Potassium hydroxide-Analytical-reagent grade. Silver nitrate solution, 0.1 N. Nitvic acid, diluted (1 + 3)-Prepared from the analytical-reagent grade acid. PROCEDCRE- Place an aliquot of the brine containing 10 to 200mg of ethylene dibromide in a 250-ml separating funnel. Add 4 to 5 ml of xylene, and shake the mixture gently for about 3 minutes, Allow the layers to separate, and then run off the lower brine layer into another 250-ml separating funnel and transfer the xylene layer to a 50-ml separating funnel.Repeat the extraction three times with 5-ml portions of xylene. Collect the xylene extracts in the 50-ml separating funnel, and shake six to eight times with 1 to 2-ml portions of water until the washings are chloride-free. Transfer the washed xylene solution to a 100-ml Pyrex-glass test-tube (30 cm long and 2 cm in diameter). Rinse the 50-ml separating funnel twice with 8-ml portions of n-butyl alcohol, and add the washings to the xylene solution in the test-tube. Add 4 to 5 g of potassium hydroxide to the test-tube, and close it with a well fitting rubber stopper. Heat the tube in a bath of boiling saturated sodium chloride solution (108" to 110" C) for a few minutes, and then shake the tube gently to saturate the solution with potassium hydroxide (about 2 N ) .Continue heating for 1 hour, and then remove the tube from the bath, and cool it under running water to room tem- perature. Transfer the contents to a 250-ml beaker with the aid of 100ml of water. Stir, and, while stirring, neutralise the solution with diluted nitric acid (1 + 3) with methyl orange as indicator, and add 2 ml in excess. Precipitate the bromide with a slight excess of 0.1 N silver nitrate solution, collect the precipitate on a fine sintered-glass crucible, wash with water until the washings are free from silver, and, finally, wash 4 or 5 times with a few millilitres each time of isopropyl alcohol to remove the xylene. Dry the precipitate a t 120" to 130" C, and weigh. Carry out a blank determination on the reagents by heating a mixture of 20 ml of xylene, 16 nil of n-butyl alcohol and 4 to 5 g of potassium hydroxide in the same way as for the sample, and deduct the weight of silver halide (if any) from that iound in the determination.If the brine to be analysed contains free halogens, they are extracted and then react im- mediately with xylene to yield halogen derivatives, which liberate halide ion on treatment with alkali. In such instances, the brine should be treated with an excess of potassium iodide and the liberated iodine titrated with 0.1 N sodium thiosulphate solution to convert the free halogen to the halide salt before extraction with xylene. RESULTS The proposed procedure has been tested with solutions prepared by dissolving weighed amounts of analytical-reagent grade ethylene dibromide in 200-ml portions of Dead Sea "salt688 NOTES [Vol.83 pan end-brine,” which is the mother liquor obtained in the solar concentration of Dead Sea water for the processing of carnallite. The composition of a typical Dead Sea “end-brine” is shown in Table I, and the results of the determinations in Table 11. TABLE I COMPOSITION OF A TYPICAL DEAD SEA “END-BRINE” Amount present, Ion present 1; per litre c1- 349 Br- 12.2 Ca2+ 47.3 Mg2+ K+ Na+ 90.4 0.7 17 Sp.gr. at 21OC = 1.340. TABLE ]:I DETERMINATION O F ETHYLENE DIBROBIIDE IN DEAD SEA “END-BRINE” Amount of ethylene dibromide in 200 ml of brine, mg 11.0 29.2 43.2 51.5 78.4 102.2 156.5 198.1 Ethylene dibromide found, mg 10.9 28.9 43.6 51.2 78.9 102.5 156.0 198.0 Error, yo - 0.9 - 1.0 + 1.0 - 0.6 +0.8 +0.3 - 0.3 - Direct extraction of ethylene dibromide from the brine with rt-butyl alcohol (or other partially miscible solvents) was not possible owing to the high solubility of magnesium and calcium halides in the alcohol. Extraction with ether and then evaForation of the ether a t 50“ C in a fractionating column 60 cm long and subsequent alkali hydrolysis in ethanolic medium gave lowpesults ( 5 to 10 per cent.) owing to losses a t the evaporation stage. When the heating period was reduced to 30 minutes under the conditions described, the results were 4 or 5 per cent.lower. We thank the Directors of the Laboratories of Israel Mining Industries for permission to publish this Note. The helpful criticism of Dr. Alexander Alon, Chief Analyst, Israel Mining Industries, is also gratefully acknowledged.REFERENCES 1. 2. 3. Lohr, L. J., Bonstein, T. E., and Frauenfelder, L. J., Anal. Chem., 1953, 25, 1115. Lawrence, M. W., and Mary, D. K., Ibid., 1950, 22, 1049. Niederl, J. B., and Niederl, V., Organic Quantitative Micro-analysis,” Second Edition, John Wilev & Sons Inc.. New York. 1942. 4. 5. 6. Safford: H. W., and Stragand, 6. L., Anal. Chem., 1951, 23, 520. Haslam, J., Analyst, 1950, 75, 371. Kennett, B. H., J . Agrzc. Food Chenz., 1954, 2, 691. ISRAEL MIXING INDUSTRIES LABORATORIES HAIFA, ISRAEL J . R. MASHALL D. A. ADER Received July Id, 1958 THE APPLICATION OF JANOVSKY’S AND MOHLER’S REACTIONS TO THE DETECTION OF BENZENE HEXACHLORIDE TWO tests based on Janovsky’sl and Mohler’s2 reactions for polynitro aromatic compounds are described for the detection of benzene hexachloride .JANOVSKY’S REACTION Janovsky’s reaction has been widely used for the detection and determination of a variety of aromatic compounds having nitratable benzene nuclei. Janovsky observed that dinitro substitution products of benzene, toluene and naphthalene gave colour reactions with acetone and alkali. The I’itali - R.lorin3 test for atropine and related allraloids, Dolin’s4 colorimetric method for determining benzene and the Schechter - Hornstein5 method for the detection and determination of benzene hexachloride are instances of the application of Janovsky’s reaction.Dec., 1958; NOTES 689 The method described by Schechter and Hornstein is based on the dechlorination of benzene hexachloride to benzene and nitration of the benzene formed to m-dinitrobenzene, which, with ethyl methyl ketone, forms a colour in the presence of alkali.The dechlorination and nitration are carried out in a specially designed all-glass apparatus. Hancock and Laws,g who made a critical survey of the method, designed a simpler apparatus in which the nitration is carried out in the cold. In both methods, however, dechlorination is effected by heating xvith zinc and glacial acetic acid. In the proposed procedure, the dechlorination and subsequent nitration are carried out in the cold in an extremely simple apparatus, namely, a Cavett flask’ (see Analyst, 1954, 79, 125). Magnesium, which reacts vigorously with glacial acetic acid in the cold, is used instead of zinc for dechlorinating benzene hexachloride. PROCEDURE- A nitration acid is prepared by dissolving 5 g of potassium nitrate in 100 ml of concentrated sulphuric acid.Between 0.5 and 1.0 ml of this acid is placed in the flask, which is then rotated to spread out the acid. A 0.2-ml portion of a solution of benzene hexachloride in glacial acetic acid is placed in the cup, three pieces of magnesium wire, each the size of a pinhead, are then added and the stopper carrying the cup is replaced immediately, 1 drop of the nitration acid being used to lubricate the joint. After 30 minutes, the stopper is removed, the flask is cooled in ice and the nitration acid is transferred to a separating funnel with about 20 to 25 ml of water. The solution is extracted with an equal volume of diethyl ether that has been washed with alkali, and the aqueous layer is discarded.The ether layer is washed with 5 ml of 2 per cent. w/v sodium hydroxide solution and then with 5 ml of a saturated solution of sodium chloride, after which it is filtered through a plug of alternate layers of cotton-wool and anhydrous sodium sulphate, the filtrate being collected in a large test-tube. Four drops of liquid paraffin are added to the filtrate, and the ether is evaporated. The residue is dissolved in 10 ml of a mixture of acetone and absolute ethanol (1 + l,v/v), 0.1 ml of a 4 per cent. w/v solution of potassium hydroxide in methanol is added, a stopper is placed in the test-tube, and the contents are mixed. A crimson colour develops in about 2 minutes and deepens after the solution has been set aside.The test is sensitive to 5 pg of benzene hexachloride. MOHLER’S REACTION Mohler described a test for benzoic acid depending on the colour formed when the dinitro derivative of benzoic acid is treated with ammonium sulphide in ammoniacal medium. The test was modified by Grossfeld,g who substituted hydroxylamine hydrochloride for ammonium sulphide. With this modification, the final colour was purer and more permanent. PROCEDURE- The dechlorination and nitration of benzene hexachloride are carried out as described for Janovsky’s reaction, but only 0.5 ml of the nitration acid is used. After 30 minutes, the flask is cooled in ice and the nitration acid is diluted with 2.5 ml of water. Five millilitres of 25 per cent. w/w ammonia solution are carefully added, and the solution is mixed. Two millilitres of 2 per cent.w/v hydroxylamine hydrochloride solution are added, the solution is mixed well, transferred to a stoppered test-tube and set aside. A violet colour develops slowly and deepens on standing. The test is sensitive to 0.25 mg of benzene hexachloride. I thank the Government Analyst, Mr. G. A. C . Sirimanne, B.Sc., F.R.I.C., for permission to publish this Note. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. COLOMBO 7, CEYLON Janovsky, J. V., Ber., 1891, 24, 971. Mohler, E., Bull. SOC. Chim., 1890, 3, 414. Morin, C., J . Pharm. Chim., 1936, 128, 545; abstracted in Analyst, 1936, 61, 504. Dolin, B. H., Ind. Eng. Chem., Anal. Ed., 1943, 15, 242. Schechter, M. S., and Hornstein, I., Anal. Chem., 1952, 54, 544. Hancock, W., and Laws, E.Q., Analyst, 1955, 80, 665. Cavett, J. W., J . Lab. Clin. Med., 1937/38, 23, 543. Grossfeld, J., 2. Untersuch. Nahr. Genusswz., 1915, 30, 271; abstracted in ..11zalyst, 1916, 41, 97. GOVERNMENT ANALYST’S LABORATORY E. RATHEKASIKKAM Received February loth, 1958690 NOTES p o l . 83 THE SPECTROPHOTOMETRIC DETERMINATION OF PERRHENATE A METHOD, which it is hoped will be described in a later paper, is being developed for the deter- mination of rhenium in organic rhenium complexes containing nitrogen. The materials are completely oxidised by fusion with sodium peroxide in a micro Parr bomb, the melt is dissolved in water, and the solution is acidified and boiled l o expel carbon dioxide, which gives a solution containing sodium, hydrogen, chloride, nitrate and perrhenate ions.Perrhenate in solution can be determined gravimetrically as nitron or tetraphenylarsonium perrhenate,l but nitrate must be absent in the first of these determinations and interferes in the second unless present in extremely low concentrations. These include the formation of highly coloured rhenium complexes in reduced solutions with thiocyanate2 and a-furildioxime? the spectrophotonietric determinztion of hexachlororhenate ion produced by reducing perrhenate in acid solution with hydrazin.e4 or chromous chloride6 and the colorimetric determination of perrhenate with 2 : 4-diphenylthiosemicarba~ide.~ Rhenium has also been determined spectrophotometrically as tetraphenykirsonium perrhenate in chloroform.' Nitrate ion is known to interfere in a number of these determinations.Custersa has determined the absorption spectrum of potassium perrhenate and shown that the ion absorbs strongly in the ultra-violet region of the spectrum. The molar extinction coefficient was 3630 at a wavelength of 230 mp, and it was indicated that Beer's law was obeyed over the range 221 to 313 mp for concentrations between 0.02 and 0*0002 M . The absorption of the perrhenate ion in the ultra-violet region does not appear to have been used in the determination of perrhenate, and investigations were therefore undertaken along these lines. The possible use of this method to determine perrhenate in the presence of nitrate was studied. A number of colorimetric methods for determining perrhenate are available. L m 0 E - Y C .- h $ U w u 8 5 Wavelengt.h, my Fig.1. Absorption spectra: curve A, potassium perrhenate; curve B, potassium nitrate; curve C, potassium chloride The absorption spectra of the perrhenate, nitrate and chloride ions were determined in cali- brated 1-cm quartz cells over the range 202 to 350 inp, a Unicam SP500 spectrophotometer and solutions of Specpure potassium perrhenate, AnalaR potassium nitrate and AnalaR potassium chloride being used. The absorption spectrum of potassium perrhenate is in close agreement with the results of Custers and of Hindman and Wehner,g who used wavelengths longer than 215 mp. The molar extinction coefficient is 3610 a t 228 mp and 6060 a t 206 mp. The chloride ion starts to absorb appreciably only a t wavelengths shorter than 210 mp, the molar extinction c0efficier.t being 1.0 at 209 mp.The nitrate ion has an absorption peak a t 303 mp ( c = 7.2) and a miniinum a t 264 mp (c = 1.6). There is a sharp rise in the value of the molar extinction coefficient for nitrate as the wavelength is further decreased, The absorption peak a t 228 mp can be used in the determination of perrhenate in solutions containing no other ions that absorb appreciably a t this wavelength. A straight line passing These absorption spectra are shown in Fig. 1.Dec., 19581 NOTES 69 1 through the origin is obtained when optical density is plotted against concentration over the range 0 to 50 p,p.m. of rhenium. The optimum wavelength for the determination of perrhenate in the presence of both nitrate and chloride is 258 mp.At this wavelength, the molar extinction coefficients for perrhenate and nitrate are 740 and 2.1. At 258 mp, a straight line is obtained when optical density is plotted against concentration over the range 0 to 250 p.p,m. of rhenium in a 0.65 M solution of analytical- reagent grade sodium chloride. (The concentration of sodium chloride in the solutions from a sodium peroxide fusion is 0.65 M.) The line does not pass through the origin, but intercepts the optical-density axis a t a value of 0.006, which corresponds to the very slight absorption of 0.05 M sodium chloride. When the absorption of the sodium chloride is taken into account, i t is found that optical-density readings for perrhenate are depressed slightly (2 per cent.) in the presence of 0.65 M sodium chloride, but, when analysing solutions of unknown rhenium concentration, allowance for this effect can easily be made by constructing a standard graph, known amounts of rhenium in sodium chloride solution of that concentration being used.The effect of potassium nitrate on the optical density of a solution containing 125 p.p.m. of rhenium in 0.65M sodium chloride was studied, and the results were in agreement with those calculated from a knowledge of the molar extinction coefficients of nitrate and perrhenate at 258 mp. In organic rhenium complexes, the ratio of nitrogen to rhenium will rarely exceed 8 to 1. Such a ratio will increase the optical-density reading for perrhenate by less than 2.5 per cent. If necessary, a correction can always be applied for the nitrate in the solution, as nitrogen in organic rhenium complexes can be readily determined by conventional methods of organic analysis.These results show that a method based on the absorption of the perrhenate ion will be satisfactory in the analysis of organic rhenium complexes. In general, the proposed method, because of its ease of application, should be useful for the rapid determination of perrhenate in simple solutions. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. THE UNIVERSITY, SHEFFIELD Hillebrand, W. F., Lundell, G. E. F., Bright, H. A,, and Hoffman, J. I., “Applied Inorganiclinalysis,” Geilmann, W., and Bode, H., Z . anal. Chem., 1948, 128, 489. Meloche, V. W., Martin, R. L., and Webb, W. H., Anal. Chem., 1057, 29, 527. Keyer, R. J., and Rulfs, C. L., Ibid., 1955, 27, 1387. Meloche, V.W., and Martin, R. L., Ibid., 1956, 28, 1671. Geilmann, W., and Xeeb, R., 2. anal. Chem., 1956, 151, 401. Andrew, T. R., and Gentry, C. H. R., Analyst, 1957,82, 372. Custers, J . F. H., Physica, 193i, 4, 426. Hindman, J . C., and Wehner, P., J . Amer. Chew SOC., 1953, 75, 2869. Second Edition, John Wiley & Sons Inc., New York, 1953, p. 320. CHEMISTRY DEPARTMENT J . B. HEADRIDGE Received July 4th, 1958 FLAME-PHOTOMETRIC DETERMINATION OF CALCIUM IN SILICATE ROCKS IN a petrological study of Godolphin granite, Cornwall, one of us (M.S.) wished to study trends in the contents of potassium, sodium and calcium oxides. As the alkalis are determined with a flame photometer, the available literature was examined for a reliable rapid flame-photometric method for small amounts of calcium oxide.It seemed that, with slight modification, the method described by Edgcombe and Hewett’ for coke and coal ash could be readily incorporated into the analytical scheme of Shapiro and Brannock.2 This Note describes the results of investigations into the suitability of this method for silicate rocks of low calcium oxide content. An E.E.L. flame photometer (Evans Electroselenium Ltd.) was used. EXPERIMENTAL The alkali granites from the Godolphin mass near Helston, Cornwall, contain quartz, albite, potash feldspar and white mica, with small amounts of topaz and tourmaline and trace amounts of apatite. They are, therefore, rich in alumina and alkali, but poor in lime and magnesia. Small amounts of titanium, iron, manganese, phosphorus, lithium, boron and fluorine are also present.692 NOTES [Vol.83 Hence, after precipitation of R,O,, the only elements likely to interfere are sodium and magnesium. Edgcombe and Hewett have shown that the error caused by sodium oxide is independent of the concentration of calcium oxide and that caused by magnesium oxide varies with the calcium oxide content. They evaluated the following equation- Percentage of calcium oxide (corrected) = Percentage of calcium oxide (uncorrected) x 100 100 + (0.8 x percentage of magnesium oxide) - - 0.05 x percentage of sodium oxide. As the rocks under investigation contain only minor amounts of magnesium oxide (0.2 to 0.4 per cent.), interference from this component is small and can be neglected. Sodium oxide, however, is present in amounts between 4.5 and 6 per cent.(in one instance 10 per cent.), hence it was thought desirable to re-investigate the magnitude of its interference. Standard solutions were prepared by dissolving anhydrous sodium carbonate and calcium carbonate in 0.5 N sulphuric acid. Appropriate aliquots of the standards mere transferred to 100-ml calibrated flasks and diluted to volume with 0 . 5 N sulphuric acid from a polythene container. After turning the sensitivity control clockwise t o its fullest extent and setting the instrument to zero against 0.5 N sulphuric acid, the scale reading for each solution was recorded. The amounts of standards used and the readings obtained are shown in Table I. The scale readings for six determinations with the same solution are given in the vertical columns A to F in Table I.Before each series, the zero setting was checked. TABLE I FLAME-PHOTOMETER SCALE READINGS FOR. STANDARD SOLUTIONS OF SODIUM AND CALCIUM OXIDES Columns .A to F represent successive series of determinations on solutions So. 1 to 10. The zero setting was checked before the start of each series, which began with solution So. 1 and ended with solution No. 10 Amount of calcium oxide Solution present, KO. p.p.m. 1 5 2 2.5 3 5 4 5 5 5 6 2.5 7 9.6 - 8 -1mount of sodium oxide present, ?- p.p.m. A - 12- 6 100 17 - 100 17- 100 11 250 12 50 14.5 50 8.5 Scale reading* B C n 6 6+ 6+ 12- 12 12 17 17 17 17 17 17 14.5 14*5+ 14.5 11.5 12 12- 9 9 9- 12.5 13- 12 Mean - scale ~. E F reading 11.5 12- 11.8 6 6 6.1 16.5 17 16.9 16.5 17 16.9 14.5- 14.5 14.5 11 11- 11.4 8.5 8.5 8.7 12- 12 12.2 Scale reading due to sodium oxide - 5.1 5.1 2.7 5.3 2.6 12.2 9 - 100 5- 5+ 5+ 5- 5- n- 4.9 4.9 10 - 50 2+ 2*5+ 2.5+ 2.5 2+ 2.5 2.5 2.5 * - and - indicate that the scale reading was estimated to be one-eighth or a multiple of one-eighth In calculating the mean scale readings, + was taken as +0.25 The readings are all a t the lower end of the scale and correspond approximately to the con- centrations of calcium oxide likely to be found in the rocks under investigation.The relationship between scale reading and calcium oxide concentration is linear up to about 25 units on the scale. The results in Table I confirm Edgcombe and Hewett's statement that the interference from sodium oxide is directly proportional to its concentration (within the errors of calculating the scale reading) and independent of the concentration of calcium oxide.I t is apparent that 5 0 p.pm of sodium oxide are equivalent to 1 p.p.m. of calcium oxide, i.e., 1 per cent. of sodium oxide increases the result for calcium oxide by 0.02 per cent., not 0.05 -per cent. as stated by Edgcombe and Hewett. A correction based on a factor of 0.05 per cent. would give a result for the calcium oxide content of sample No. C, (see Table 111) much below that calculated from optical measurements. The results of tests made a t higher calcium oxide concentrations were more varied, although the following figures show that the correction factor is still fairly close to 0.02- of a scale division (one scale division = 2).and - as -0.25, e.g., 12- is the same as 11.5$, i . e . , 11.78. Amount of calcium oxide, p.p.m. . . 25 25 10 10 Amount of sodium oxide, p.p.m. . . 100 50 100 50 Factor , . . . . . . . . . 0.026 0,018 0.021, 0,017 0.020, 0,014Dec., 19581 NOTES METHOD REAGENTS- 693 All reagents are of analytical-reagent grade. Sulphuric acid, concentmted. Sulphuvic acid, 0.5 N. Hydrofluoric acid, 40 pev cent. w/u. Ammonium hydroxide solution (1 + 1)-Mix equal volumes of ammonium hydroxide solution, Standard calcium solutions-Dry calcium carbonate a t 110' C, and prepare solutions containing sp.gr. 0480, and water. the equivalent of 10 and 50 p.p.m. of calcium oxide in approximately 0.5 AT sulphuric acid. PROCEDLIRE- The procedure described is based partly on Edgcombe and Hewett's method' and partly on Shapiro and Brannock's method.2 Accurately \veigh about 0.2 g of powdered rock sample, which has been crushed to pass through a 120-mesh sieve and dried a t 110" C, into a platinum crucible.Add 10 ml of hydrofluoric acid and 3 ml of concentrated sulphuric acid. Cover the crucible with a lid and place i t on a water bath. Remove the lid and reduce the volume to about 3 ml. (If the method of digestion recommended by Shapiro and Brannock is used, 1 ml of concentrated nitric acid is now added.) Remove the crucible from the water bath and heat gently until fumes of sulphur trioxide are evolved. Allow the crucible and contents to cool, fill the crucible with distilled water and digest on a ivater bath for about 30 minutes. If there is an insoluble residue, transfer the solution to a Vitreosil beaker, add 20 t o 30 ml of distilled water (including washings) and boil for about 10 minutes.(If any residue remains after boiling, filter the solution and examine the residue for calcium-bearing minerals with a petrological microscope.) Cool, transfer the solution to a 200-ml calibrated flask and dilute to the mark with distilled water. Immediately transfer the solution to a polythene container. By pipette, place a 25-ml aliquot of the solution in a centrifuge tube, add one or two drops of methyl red solution and ammonium hydroxide solution (1 + 1) dropwise until the red colour just changes to yellow. Spin in a centrifuge a t about 2500 r.p.m. a t 14-cm radius for 3 minutes and then decant the supernatant liquid into a 50-ml calibrated flask.A double precipitation of H,O, is usually necessary. Turn the sensitivity control of the flame photometer clockwise to its fullest extent and adjust the zero setting against 0.5 AT sulphuric acid. Determine the calcium oxide content of the sample solution by comparing the scale reading with that of the standard containing 10 p,p.m, of calcium oxide. If the sample contains more than 10 p.p.m. of calcium oxide, it may be necessary to construct a calibration curve by using the standard solutions containing 10 and 50 p.p,m. of calcium oxide, together with suitable intermediate standards. (In this instance, adjust the sensitivity control to give full-scale deflection with the standard containing 50 p.p.m.of calcium oxide.) Allow the sample to digest overnight or until digestion is complete. Dilute to the mark with 0.5 9 sulphuric acid. TABLE I1 DETERMINATIOX OF CALCIUM OXIDE IN SILICA BRICK Samples 1 to 4 were taken from the same container. Each analyst used a different aliquot of the. same sample solution Amount of calcium oxide found by Amount of calcium oxide found by Sample So. M. Stone, J . E. Thomas, o/ 1 1.71 1 2 1.75 1.67 3 1.67 1.69 4 1.66 1.68 Average Mean amount of calcium oxide found, Yo 1.69 1.71 1.68 1.57 . . 1.69 RESULTS To test the proposed procedure for silicate rocks, determinations were made on four samples. Two 25-ml aliquots of each One set of samples was analysed by A C S , the calcium oxide from one bottle of British Chemical Standard No. 267 (silica brick).sample solution were analysed.[Vol. 83 content being determined from the mean of twenty instrument readings, and the other set by J.E.T., the calcium oxide content being determined from the mean of thirteen instrument readings. The results, which are shown in Table 11, are lowel- than the average of the nine analyses given with the sample (1.75 per cent.), but are well within the range stated (1.66 to 1.80 per cent,), and, in fact, show a slightly greater precision than the gravimetric and volumetric determinations. In addition, determinations were made on four samples, each taken from separate bands in the banded “granite” sheets near Porthleven, Cornwall. The results, which are shown in Table 111, are in good agreement with determinations made by using ethylenediaminetetra-acetic acid.However, it should be noted that the second decimal place is stated for comparison in these Tables only; it has no real significance in the methDd used. 694 NOTES, TABLE I11 AMOUNTS O F CALCIUM APiD SODIUM OXIDES I N TOPAZ - TOURMALINE - ALBITE GRANITES .\mount of calcium oxide found by Amount of calcium A\mount of calcium titration with Amount of sodium oxide found oxide found ethylenediamine- Sample So. oxide found, (uncorrected), (corrected), tetra-acetic acid, % /O 70 Yo O/ .5.51 4.32 4.43 5.46 0.47 1.13 0.47 0.35 0.36 1.04 0.38 0.24 0.32 1.02 0.41 0.23 COXCLUSIONS The proposed procedure can be applied to rocks containing up to about 2.5 per cent, of calcium oxide. I t is sufficiently accurate for calculating normative values and compares favourably with existing rapid methods.Provided that a calibration curve is used, it is possible to determine amounts of calcium oxide up to about 7 . 5 per cent. The correction factor for sodium oxide is more variable, hence results are liable to be less accurate for rocks containing appreciable amounts of this component. The time taken for a single analysis (including five scale-reading observations), once the rock has been digested and the sample solution diluted to volume, is about 30 minutes. REFERENCES 1. Edgcombe, L. J., and Hewett, D. R., Analyst, 1954, 79, 755. 2. Shapiro, L., and Brannock, W. W., “Rapid Analysis of Silicate Rocks,” U.S. Geol. Survey Bull. N o . 1036C, 1956. DEPARTMENT O F GEOLOGY UNIVERSITY COLLEGE KEELE, STAFFORDSHIRE M.STONE J. E. THOMAS Received May 8th, 1958 THE DETERMINATION OF NITROGEN IN CERTAIN FLUORINATED COMPOUNDS BY THE KJELDAHL METHOD PUBLISHED methods for the determination of nitrogen in fluorinated organic compounds have been reviewed by Macdona1d.l The only reference to an attempt to use the Kjeldahl method appeared in a paper by Rush, Cruickshank and Rhodes,z who stated that, for perfluoro compounds, the method was usually unsuccessful. We publish this Note in order that this almost complete absence of reference to the Kjeldahl method shall not give the impression that it cannot be used for the analysis of any fluorinated materials. We have successfully analysed a variety of solid fluorinated materials, some typical results being shown in Table I.The procedure of Belcher and Godbert3 was followed, except that we distilled into standard hydrochloric acid instead of boric acid, as previous experience with non- fluorinated materials had shown that more consistent results would be obtained in this way.Dec., 19581 SOTES 695 I t can be seen from Table I that no interference was caused by the presence of fluorine, even in the analysis of compounds containing nitro groups, which were subjected to phosphorus- hydriodic acid reductionS before digestion. TABLE I DETERMINATION OF NITROGEN IN FLUORIKATED COMPOUNDS Calculated Amount of nitrogen Calculated Compound amount of nitrogen, found, amount of fluorine, % % % C,H,.NH.CO.CF, . . . . 7.41 7.36, 7.36, 7.45, 30.14 CF,[CH,~OCO~C6H,~NOz]2 . . 6.83 6.64, 6.73 9.26 CH,.C0.NH.C6H3(CF3)~NOz .. 11.29 11.23, 11.21 22.97 C.H..CO.CF,,C(:~OH).C.H, . . 5.09 4.83, 4.85 13.80 7.37, 7.40, 7.39 6.51 2.61 5.90, 5.93 12.02, 12.03 6.45, 6.36 2.61, 2.60 31.91 33.91 30.91 49.52 * Analysis for other constituents indicated that this compound was not quite pure. As might be expected, some slight etching of the digestion flasks takes place, but this is, in fact, an advantage in that it markedly reduces bumping of the digestion mixture, which is otherwise liable to occur. We thank Mrs. M. W. Roberts for experimental work and Mr. E. J. P. Fear and Dr. I, M. White for supplying samples. REFERENCES 1 . 2, 3. hlacdonald, A. hl. G., I n d . Chem. A’Wjr., 1987, 33, 360. Rush, C. A,, Cruickshank, S. S., and Rhodes, E. J. H., Mikrochim. Acta, 1956, 858.Uelcher, K., and Godbert, A. L., “Semi-Micro Quantitative Organic Analysis,” Second Edition, Longmans, Green & Co. Ltd., I-ondon, 1964, p. 102. T. R. F. W. FENNELL J. R. WEBB ROYAL AIRCRAFT ESTABLISHMENT FARBBOROUGH, HANTS. Received May Sth, 1958 A NEW pH IXDICATOR A NEW pH indicator has been prepared by condensing sodium 1 : 2-naphthaquinone-4-sulphonate with 2 : 4-dinitrophenylhydrazine. The mechanism of the reaction is analogous to the condensation of asymmetric alkyl- and arylphenylhydrazines with 1 : 2-naphthaquinone, and the product is an o-hydroxyazo compound.1 The advantages of the new indicator are (a) it can be easily prepared in a pure crystalline state, (b) it is soluble in water, ethanol and ethanol - diethyl ether mixtures, (c) it changes colour over a narrower pH range than most other indicators, ( d ) small concentrations of it are effective, (e) it is equally effective either in titrating acid with alkali or vice veysa, (f) it is extremely sensitive, even when titrating 0.001 N solutions, (g) ageing, particularly with respect to air and light, has no effect on it, and (h) it is suitable for preparing indicator test-papers. EXPERIMENTAL PREPARATION OF THE INDICATOR- A solution was prepared by dissolving 0.99 g (0.005 mole) of 2 : 4-dinitrophenylhydrazine in 100 ml of hot ethanol.While still hot, this solution was gradually added, with continuous shaking, to a solution of 1.3 g (0.005 mole) of sodium 1 : 2-naphthaquinone-4-sulphonate in 25 ml of hot distilled water. The reaction mixture, which assumed a dark red colour, was then boiled for 10 minutes.A blood-red crystalline solid separated from the hot solution. After 30 minutes, this was removed by filtration and recrystallised from glacial acetic acid. The yield of recrystallised product was 1.7 g, which was found to contain 48.22 per cent. of carbon, 2.53 per cent. of hydrogen, 12.21 per cent. of nitrogen, 6.98 per cent. of sulphur and 4.7 per cent. of sodium. The formula C,,H,O,N,SNa requires 43.64 per cent. of carbon, 2.05 per cent. of hydrogen, 12.73 per cent. of nitrogen, 7.27 per cent. of sulphur and 5.2 per cent. of sodium.696 NOTES [Vol. 83 A stock solution was prepared by dissolving 0.1 g of solid indicator in 125 ml of 96 per cent. ethanol and diluting to 250 rnl with distilled water. This solution was orange-red; i t was stored in a brown bottle.pH R-4NGE- Buffer solutions with pH values between 5.2 and 12 were prepared. To 10 rnl of each buffer The colour was rose-red in buffer solutions In the pH range 8.4 to 9.2, the indicator solution, 3 drops of indicator solution were added. of pH below 8.4, and violet a t pH values above 9.2. produced purple-violet colours. INDICATOR TEST-PAPERS- of the indicator in 50 per cent. ethanol for 15 minutes and then dried. a rose-red colour and was sufficiently sensitive to detect 0.01 A’ solutions of alkalis. A Whatman No. 1 filter-paper was cut into small strips, soaked in a 0.1 per cent. solution The test-paper assumed APPLICATIONS OF THE INDICATOR The indicator has been used in determining the acidity of urine and vinegar, the acid value of oils and water-insoluble organic acids, and also in the urease test.It is not suitable for titrating free sulphuric acid in a solution of copper sulphate or for assaying vegetable alkaloids. For example it forms crimson crystals with strychnine, a purple-violet colour with brucine and an intense blue colour with atropine. This can be used to differentiate between strychnine and brucine if a fen. crystals of each are treated with 2 drops of indicator solution on a white porcelain plate. REFERENCE 1. Friez-David, H. E., Blangey, L., and Kaul, H., Helv. Chim. Acta, 1946, 29, 1765. BIOCHEMISTRY DEPARTMENT M. Z. BARAKAT CAIRO UNIVERSITY M. M. EL-SADR FACULTY OF VETERINARY MEDICINE s. K. SIIEH.4B GIZA, CAIRO Received July 15th, 1958 REDOXOKINETIC TITRATION--A NEW ELECTROANALYTICAL TECHXIQUE Doss and Agarwall discovered the rectifying property of reversible electrodes, which they de- signated the “redoxolrinetic effect,” since the rect.fication is dependent on the kinetics of oxida- tion - reduction reactions at the electrodes. They elaborated2 the theory of the effect, their de- ductions being based on the theory of absolute reaction rates proposed by Glasstone, Laidler and - k I Volt v Stabilised voltage supply - E ~ r i n g . ~ a new electroanalytical technique known as radio-frequency p~larography.~ A more general theory has recently been formulated by Barker, who, in addition, evolved The application ofDec., 19681 NOTES 697 the effect to the determination of end-points in redox titrations is described in this Note.The arrangement of apparatus is shown in Fig. 1. Acidified ammonium ferrous sulphate solution was titrated against potassium permanganate solution. After each addition of permanganate, the redoxokinetic potential was determined a t a fixed ax. potential. In normal redoxokinetic work, a small a.c. voltage (10 mV, r.m.s.) is generally used, as this helps in the quantitative interpretation of results. For this work, how- ever, it is advantageous to use higher voltages (25 to 100mV, r.m.s.). A typical set of results for the titration of 25 ml of 0.02 N ammonium ferrous sulphate (acidified with 100 ml of 4 N sulphuric acid) with approximately 0.02 W potassium permanganate is shown in Fig. 2, the visual end-point being indicated by an arrow.The apparent surface area of the electrode was 0.1 sq. cm, and the a.c. voltage was 50 mV, r.m.s. I t has been found that the end-point, which is accompanied by the greatest change in redoxokinetic potential, can be determined with an error of t O . 4 per cent. a t a concentration of 0.02 N, which shows the suitability of the technique for analytical work, O- 0 \ - IOO- I I I 0 10 20 30 Potassium permanganate added, ml I I -loo, 0 10 20 30 Fig. 2. Redoxokinetic titration of 25 in1 of 0.02 N ammonium ferrous sulphate with approximateiy 0.02 N potassium permangan- ate at constant a.c. potential Fig. 3. Redoxokinetic titration of 2.5 ml of 0.02 N ammonium ferrous sul- phate with approximately 0.02 N potas- siumpermanganate under constant current conditions A redoxokinetic titration can be carried out under constant current conditions, i.e., without re-adjustment of the a x .potential to a particular value after each addition of reagent. The galvanometer is read after each addition. A typical set of results for the titration of 25 ml of 0.02 N ammonium ferrous sulphate (acidified with 100 ml of 4 N sulphuric acid) with approxi- mately 0.02 N potassium permanganate a t a constant current of 200 FA, r.m.s., is shown in Fig. 3. This modification simplifies the procedure, and the end-point can be determined with the same precision as before. It is interesting to note that the end-point often coincides with a galvanometer reading of almost zero, but it must be pointed out that, by adjusting the composition of the solution to be titrated, i t is possible for the galvanometer reading to be widely different from zero a t the end- point, I t is hoped that the significance of this, and the general theory of redoxokinetic titration, will be dealt with in a separate paper.The apparent surface area of the electrode was 0.1 sq. cm.698 N0TE.S REFERENCES 1. 1. ~ . PYOC. Indian Acad. Sci.. 1951. 34. 263: 1952. 35. 45. Doss, K. S. G., and Agarwal, H. P., J . Sci. rnd. Res., 1950, 9 ~ , 280. [Vol. 83 3 . 4. Glasstone, ’S., Laidler, K. J . , and Eyring,’H.,’ “The The& of Rate Processes,” McGraw-Hill Book Barker, G. C., Anal. Clrim. Ada, 1958, 18, 118. Co. Inc., Xew York, 1941, p. 575, CESTR.4L ELECTROCHEMICAL RESE.4RCH IXSTITUTE RAMANAD DISTRICT KARAIKUDI, INDIA K. S. G. Doss U.H. NARAYANAN K. SUNDARARAJAN Received June 1 Ith, 1958 IDENTIFICATION OF GLASS FRAGMENTS BY THEIR PHYSICAL PROPERTIES THE measurement of the physical properties of glass fragments, particularly density and refractive index, is commonly used in forensic problems as ;L means of identifying the object from which the fragments originated.1 t o The reliability with which identification can be made depends on the variation of these physical properties, both within the object and between objects. To find the amount of variation, measurements have been made of the physical properties of glass fragments from sixty-one different objects. EXPERIMENTAL The objects studied were bottles of several types, headlamp glasses, ophthalmic lenses and xvindow and plate glasses, all of which are commonly encountered in forensic work.Fragments from these objects \rere examined for fluorescence a t two exciting wavelengths (2536 A and betiyeen 3000 and 4000 .aj, and measurements were made of refractive index and dispersion (both determined with an Abbk refractometer) and density, both by displacement of water and by the use of sensitive density These columns were prepared in a thermostatically controlled glass tube by successively adding twenty-six bronioform - bromobenzene mixtures of regularly decreasing density. After the column had been set ,aside for a t least 72 hours, the giass chips were placed in it, and their distribution at equilibrium was noted. RESULTS m u ISC CESSION Fluorescence was observed only with ophthalniic lenses, although Marris’ has reported the use of this property in the examination of window glass.One hundred ophthalmic lens blanks, including a number of bifocals, were examined, only one of which did not exhibit some fluorescence. In general, different colours were observed a t the two exciting wavelengths, and, without exception, the two parts of each bifocal lens showed different fluorescence. The results of dispersion measurements offered little encouragement for the use of this property. When significant differences between fragments were found, they were small, and were invariably accompanied by large differences in refractive index. Absolute measurements of refractive index on thirteen ophthalmic lenses from several different sources gave results between 1.5230 and 1.5242 ( ~ ; O ~ O O O l j , which suggests that ophthalmic lenses cannot readily be differentiated one from another by this property, although, as a group, they have a considerably higher refractive index than the, other glasses.Bottles also tended to group together; the refractive indexes of thirty-one widely different types of bottle were between 1.5120 and 1.5170. However, headlamps and window and plate glasses showed \vide variations in refractive index. Observations of relative refractive index were also made by examining the Becke lines of chips of glass in a refracting medium. It was found that the refractive-index range of the immersion liquid over which the Becke line disappeared depended partly on the orientation of the chip on the microscope stage and partly on the edge observed. The reliability of these observations was improved by using a univcrsal stage and selecting a chip edge for which the range \\-as a minimum. Some objects were sampled a t several different positions, and, in all instances, variation in refractive index from point to point was found to be negligible. Densities of fragments were measured to an accuracy of +0.00004 g per cc at 20’ C, and a scatter diagram of density against refractive index revealed some degree of correlation betireen these properties; this has also been observec! by Gamble, Burd and Kirk.2 The densities of the ophthalmic lenses were in a restricted range (2.5084 to 2.5184), but those of the other types of object showed wide ranges. Density differences from point to point in a single bottle were found to be quite large, which agrees with the findings of Sawai, Tashiro and Umeya.8 This wasDec., 19581 APPARAlU S 699 studied further by examining the distributions of a number of chips from the same bottle in density- gradient columns. The largest spread observed was estimated t o be 0.00230g per cc, and the total range of density of thirty of the thirty-one bottles studied was 0.0225g per cc. Other randomly selected bottles showed spreads estimated as 0.00194, 0.00133, 0.00075 and 0.00030g per cc. The other types of object showed much smaller spreads, which can probably be neglected. REFEKEXCES Such studies showed a i d e spreads of density within bottles. 1 . Kirk, P. L., “Crime Investigation. Physical Evidence, and Police Laboratory,” Interscience 2. 3. 4. 5. 6. Kirk. I-’. L., “Densitv and Refractive Index. Their ADDlication in Criminal Identification.” Publishers Inc., Kew York, 1953. Gamble, L., Burd, D. Q., and Kirk, P. L., J . Cviiii. Lam Cviniinoi., 1943, 33, 416. Roche, G. IT., and Kirk, P. L., Ibid., 1947, 38, 168. Greene, R. S., and Burd, D. Q., I b i d . , 1949, 40, 55. Kirk, I’. L., and Dollar, A. AT., Ibid., 1949, 39, 684. I I Charles C.’ Thomas,‘ Springfield, Ill., 1951, p. 49. 7. 8. hIarris, N. A,, *47zaZyst, 1934, 59, 656. Sawai, I., Tashiro, €I., and Umeya, K,, Bull. Tli5t. Chew. Res., Kyoto Univ., 1952, 30, 40. DOMINION LABORATORY J FINCH DEPARTYBKT OF SCIEXTIFIC AND INDUSTRIAL RESEARCH I-’ P. WILLI~MS WELLISGTOX, XEW ZEALAXD First received Decembev 23rd, I957 Amended, .4 ugztst I s t , 1938
ISSN:0003-2654
DOI:10.1039/AN9588300684
出版商:RSC
年代:1958
数据来源: RSC
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14. |
Apparatus. A modified design of the Audus soil-perfusion apparatus |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 699-701
C. M. Sims,
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PDF (211KB)
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摘要:
Dec., 19581 APPARAlU S 699 Apparatus A MODIFIED DESIGN OF THE AUDUS SOIL-PERFUSlON APPARATUS LEES and Quastell described an apparatus in which soil was continuously perfused with a dilute solution of ammonium sulphate, the rate of nitrification of the ammonia being followed by quantitative nitrate determinations on the perfusate. The perfusate mas circulated by positive air pressure, which was produced with an alternating water pump. The apparatus was somewhat cumbersome, and Audus2 modified the design so that negative pressure was used to lift the perfusate to the top of the soil column. This less bulky design was used successfully in this department for several years for soil nitrification studies.3 Temple* modified the Audus design to a smaller form consisting of only two parts, which, however, required some adjustment before perfusion began. The apparatus was rather complicated and was more difficult to construct than either the Audus or the proposed perfuser.The enrichment technique for the isolation of various soil bacteria was greatly simplified by using the perfusion apparatus, and Lees5 claimed to have isolated pure cultures of nitrifying bacteria on a column of glass beads perfused with dilute solutions of ammonia. Soil perfusion was used in this laboratory for the enrichment of soil samples before the attempted isolation of nitrifying bacteria from soils in which very few of these organisms were present. The use of large numbers of perfusers led to the development of a more compact design, which, however, still used the same principle as the Audus apparatus.The small size of the apparatus permitted a large number of perfusers to be housed in a small incubator. DESCRIPTION OF THE APPARATUS The perfuser (see Fig. 1) was made from a 500-ml Pyrex-glass Florence flask, A, the neck of which was removed and replaced by the tube D (15 cm long and 2.8 cm internal diameter), The soil sample was introduced a t the top of tube D, the rubber stopper being immediately replaced. At the point of fusion into the flask, tube D was constricted to 0.5 cm to prevent soil from falling into the flask. A constriction of diameter 1 to 2 mm was made in the side-arm, C, a t its point of fusion, B, into the flask, and the side-arm was then bent a t 90" and extended to the same height as the top of flask A.For smooth operation of the apparatus, the constriction a t B had to be less than 2 mm in diameter so as t o supply the necessary resistance to impede the flow of liquid back into the flask. Without this resistance, air was drawn into the flask instead of up tube F with the perfusate. Tube F had an internal diameter of 7 mm, and was fused into the right- angle bend of the side-arm, C. This position was empirically found to give the best flow of air and perfusate up tube I;, the other end of which was fused into tube D about 5 cm from the top. Tube E, which led to a water pump, had the same internal diameter as F and was fused into the top of tube D and into flask A. The air flow was controlled by a clip on the rubber tubing leading700 APPARATUS [Vol.83 to the pump. Tube E joined tube D about 2 cm above tube F to prevent loss of perfusate by suction into tube E. A cotton-wool plug protected the open end of tube E from contamination, and a piece of glass tubing, G, filled with cotton-wool, was placed in the top of the side-arm C to reduce the air flow into tube F and to prevent aerial contamination of the perfusate. No constriction was necessary in tube E. E I Time, days Fig. 2. Accumulation of nitrate and nitrite nitrogen on perfusion of 30 g of garden soil with 300ml of 0.01M ammonium sul- phate for 21 days at 30°C: curve A, nitrate nitrogen; curve B, nitrite nitrogen METHOD OF OPERATION Fresh garden soil collected from the 0 to 2-inch horizon was air-dried for 24 hours and then thoroughly mixed with 0.3 per cent.of a soil conditioner (Krilium, obtained from Jlonsanto Chemicals, Australia). The 0.5 to 2.0-mm crumb fraction was collected. Thirty grams of soil were then carefully introduced into tube D, layers of glass-wool being placed above and below the soil column to hold the crumbs in place and prevent “puddling.” The soil was perfused with 300 ml of 0.01 M ammonium sulphate for 4 weeks in an air-jacketed incubator therniostatically controlled a t 30” & 2” C. The initial level of liquid in the reservoir was marked on the side of flask A and was kept constant by adding sterile distilled water a t least 2 hours before the daily sample was collected for analysis. The level of liquid in 4 was adjusted so that the flask was a t least half full, and 300 ml of perfusate was found to be most satisfactory. When the level of liquid fell below halfway, the perfusate did not ascend tube F and perfusion became irregular.The nitrification rate in the soil was determined by plotting the nitrate-N content of the perfusate against time. When the perfusion experiment had been completed, the soil sample was shaken from tube D, and the apparatus was thoroughly washed in hot soapy water and cleaned with acid to remove all traces of carbonate and soil. The perfuser was then washed several times with distilled water and finally with water containing 0.2 per cent. of sodium hydrogen carbonate. The open ends of the perfuser were plugged with cotton-aoo:l and covered with paper to prevent saturation of the plugs with water. The perfusers were stcrilised by heating in an autoclave a t 120” C for 20 minutes.RESULTS When the nitrate-N in the perfusate was plotted against time, a sigmoid type of curve similar to that reported by Lees and Quastell was obtained. No nitrate or nitrite formation was detectable for 2 days, after which nitrite formation increased markedly. The rate of formation was linear until a maximum of 100 pg of nitrite-N per ml was reached after incubation for 12 days. After 10 Cays, the nitrite was utilised a t an increasing rate, and could no longer be detected in the perfusate by the eighteenth day. Nitrate was detected after 2 days, and its rate of formation then increased rapidly and became linear by the ninth day. Typical results are shown in Fig. 2.Dec., 19581 APPARATUS 701 The nitrate-N increased to 250 pg per in1 after incubation for 18 days, and reached a peak of 270 pg per ml by 21 days; ammonia could no longer be detected after the twelfth day.The perfusate initially contained 280 pg of ammonia-N per nil, almost all of which was later detected as nitrate-N. Perfusion of both soil crumbs and glass-bead columns with dilute ammonia solutions showed that the proposed apparatus worked satisfactorily, both qualitative and quantitative tests showing that, as the ammonia disappeared, it was replaced by nitrite and later nitrate. DISCUSSION OF RESULTS The apparatus described has been used in this laboratory, together with the Audus perfuser, for quantitative nitrification studies on soil for 12 months. I t was also used to detect very small numbers of nitrifiers in desert soils frcm Central Australia, and also for the partial purification of nitrifiers by Lees’s m e t h ~ d .~ However, pure cultures of nitrifying bacteria were not obtained after prolonged perfusion in either the Audus or the proposed apparatus. In all experiments, the nitrification curves closely resembled those reported by Lees and Quaste1,l i . e . , the alteration to the design of the perfuser did not affect the growth or the nitrifying activity of the ammonia- oxidising bacteria. The only difference noted when results obtained with the proposed apparatus were compared with the earlier reports was the transient accumulation of extensive amounts of nitrite-X in the perfusate before nitrate was detected. The nitrite accumulation appeared t o be a characteristic of the apparatus, as it was observed in all quantitative experiments.I t was smaller and more compact, and stood on the bench without the support of a retort stand. More than twenty perfusers were operated by a single water pump through a manifold fitted in an incubator 4 feet x 3 feet x 2 feet. The pump was run slowly, as only slight negative pressure was sufficient to lift the perfusate to the top of the soil column. The noise from the water pump was overcome, a desirable factor when the perfusers were in a room constantly used by other workers. The proposed perfuser was made in one piece, which overcame the problem of breakages that occasionally occurred when the Audus apparatus was assembled or dismantled. In spite of its compact design, the apparatus could be cleaned quickly and easily. Finally, the apparatus was easy to construct and relatively cheap to produce. The design would be useful in all problems. for which the Audus perfuser was suitable, and its small size rendered it particularly valuable \\.hen large numbers of perfusers had to be housed in a limited space. The perfuser had several advantages over earlier designs. We thank Mr. H. Uffelmann for technical assistance in the manufacture of the perfusers. REFERENCES 1 . 2. 3. 4. 5. Lees, H., and Quastel, J. H., Riochenz. J . , 1946, 40, 803. Audus, L. J., Nature, 1946, 158, 419. Collins, F . Bl., Awstml. J . Agric. Hes., 1954, 5, 688. Temple, K. L., Soil S c i . , 1951, 71, 209. Lees, H., Nature, 1951, 167, 355. DEPARTMEXT OF BACTERIOLOGY UNIVERSITY OF A4DELAIDE SOUTH AUSTRALIA c. M. SIMS F. M. COLLINS Received June 17th, 1968
ISSN:0003-2654
DOI:10.1039/AN9588300699
出版商:RSC
年代:1958
数据来源: RSC
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15. |
Book reviews |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 702-707
A. L. Bacharach,
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摘要:
702 BOOK REVIEWS [Vol. 83 Book Reviews THE UFAW HASDROOK ON THE CARE AND MANAGEMEKT O F LABORATORY ANIMALS. Edited by ALASTAIR N. WORDEN, M.A., BSc., M.R.C.V.S., F.R.I.C., and W. LANE-PETTER, M.A., M.B., B.Chir. Second Edition. Pp. xx + 951. London: The Universities Federation for Animal Welfare. 1957. Price 70s. Every year, in the United Kingdom alone, something between two and a half and three million animals are used in laboratories for standardising pharmaceutical and pesticidal preparations, including some of the “pure” active principles of which they are formulations, for research in the medical and paramedical fields, as well as into general biological problems, and for teaching purposes, mainly to medical students, but also t o those wishing to qualify in physiology, pharma- cology, biochemistry and some other specialised disciplines of biological science.For all these purposes it is of the essence of the contract that the animals shall be alive a t the time of the experiment; their use is subject to the provis’ions of the 1876 Cruelty to Animals Act, as administered by the Home Office and its specially appointed and highly qualified inspectors. The uses of these animals are manifestly pretty varied; the procedures and techniques that these uses elicit are even more varied than might consequently have been expected. They include simple feeding tests involving changes in dietary composition so subtle that nothing but experi- ments on animals can reveal them or, alternatively, with so direct a bearing on the health of animals that only experiments on animals can be hoped to provide an answer to the posited problem ; single or serial injections of substances intended to protect against specific infections, generally bacterial or viral; operations for the partial or total removal of a particular gland or tissue, with a view to studying the deprived animal’s reactions to stimuli of normal or abnormal kinds and to establishing the relation of the g1ar.d or organ to normal physiological processes or their pathological disturbances ; and experirnexs on whole animals subjected to extremes of temperature, pressure or humidity, conducted for the light they may throw on the increasingly complex range of conditions, including radiation hazards, to which Homo sapiens-and to a less extent his domestic and farmyard animals themwlves-is being exposed.Anyone who holds either that these goals are none of them worth aiming at, or the commoner and equally unrealistic view that their importance is insufficient to justify the use of sentient but inevitably non-consenting animals, will not want to read, and even more certainly ivill not waiit to buy, the much enlarged new edition of the UFAW Handbook, already highly esteemed by all those who have to breed or use laboratory animals; what is more, he will not need to read this review and is advised to stop a t this point, if he has already gone so far. For this is not the place, if there is one, in which to argue with those who think (or say they think) that experiments on animals are incapable of giving answers to problems of human health and disease and who some- times even go so far as to extend these alleged doubts to animal health and disease; nor would i t be fitting to enter into ethical and philosophical arguments with those who, prepared to admit that useful knowledge can be gained by these means, deny that it is permissible for moral man to do so.Rather is it my intention here to emphasise another fact that should have a special appeal to the scientifically objective observer, whether or not he is directly himself involved in the problems of laboratory animal husbandry. This book, of which the first edition appeared over 10 years ago and was under half the size of the second, gives overt evidence of a meeting-point for two parties only too often thought by superficial or biased observers to be for ever irreconcilable.The humanitarian-who might in this context mme suitably be dubbed the animalitarian or even the philozoist-is clearly concerned to ensure thac unnecessary suffering is not undergone by any animal, outside or inside a cage; he generally gcles further than this and takes a more positive attitude, insisting on the animal’s “right” to be as contented as it is possible for man, with or without the active connivance of nature, to make him. Thus it is not a matter for suprise that a body such as The Universities Federation for Animal Welfare s8hould be taking the problems of the laboratory animal with the utmost seriousness. In this book there are, besides chapters on more general matters, such as the legal aspects of the situation, equipment of all kinds (from water bottles and hypodermic needles to cages and ventilation systems), nutrition, breeding, record keeping, choice of species and strain, pests and hygiene, also individual chapters on some thirty-four species of laboratory mammals belonging to the rodent, lagomorph, insectivore and carnivore groups, four chapters on the domesticated ungulates, two on primates, one on marsupials and four on birds, not to mention some chapters on the cold-blooded vertebrates and several on invertebrates.There is also a chapter of notes on species not elsewhere dealt with in the book: this constitutesDec., 19581 BOOK REVIEWS 703 in itself a guide to a somewhat esoteric zoo, its inhabitants ranging from raccoons, bobcats, lemmings and susliks, through vampire bats, locusts and tse-tse flies, to leeches and the snail, Lymnaea; Drosophila, needless to say, has already had a chapter to itself.From this it seems so clear as to make its mention a work of supererogation that the Federation, when in its title it refers to animal welfare, means the welfare of all animals, however obscure and to some even unpleasant. Except, it may seem, when the animal may fairly be described a s a “pest” towards one of the more warmly regarded “higher” species, though the Federation would presumably press for humane methods of exterminating even lice and bed-bugs. Before such rather extreme problems of kind-heartedness arise, there will have taken place the somewhat unexpected meeting to which I have already alluded.The experimental or analytical user of animals had, before and during the first years of World War 11, been getting increasingly anxious about his supplies of laboratory animals. Not only was he finding it more and more difficult to get enough of them, and particularly of certain species, b u t their somewhat vaguely defined and assessed “quality” was, if anything, deteriorating. In his own interests, both scientific, for animals in a poor condition will as often as not provide the experimenter and analyst with equivocal results, and economic, because bought animals that die before you can use them are of less than no interest to anyone-even to the vendor who has already been paid for them-he was compelled to examine in detail the conditions under which his experimental animals were being produced and the effect of those conditions on the animals’ quality.The results of this examination were already known to some, and had been even assiduously brought by a few of them to their colleagues’ attention, though they were expected by many and welcomed by all. The efficiency of any laboratory animal as a “tool” in standardisation or investigation was directly correlated with its bodily and “mental” health; put in another way, the number of animals required in any test or experiment to provide significance of results a t any pre-determined level bears an inverse relationship to the well-being of the animal. You could either get better results with the same number of healthier animals or equally trustworthy results with a smaller number of healthier animals.Thus science and economics on the one hand found common cause with charity on the other. Even if there had ever been the slightest justification for believing that scientists, and especially those working in fundamental or applied biology, were less scrupulous in their behaviour or less sincere in their kindliness towards “lower animals” than any otherwise similar group of men and women-and there never has been any evidence a t all for so disquieting a view-it would now have been clear that it pays to be kind to “our dumb (and not so dumb) friends.” The permanent alliance to which this book is eloquent witness will no doubt be a thorn in the flesh of those who, from good motives and ignorance or from evil motives and dishonesty, have insisted that the animal lover and the “vivisectionist” are poles asunder.On the contrary, there is a territory, the territory covered by this book, over which their interests are not merely compatible, but complementary and often identical. And so it is that this book must be permanently in the hands of everyone who is responsible for the provenance, whether by purchase or breeding, of laboratory animals or their use as scientific reagents. It will help him to correct any errors he may be-as who is not occasionally?-already committing with species of animals currently in use; it will be an essential standby against the day, which will almost certainly come, when he is called on to handle animals of a species previously alien to his laboratory. Indeed, it may well help him to decide whether i t will be well to add to the species available to him, and if so which and how.Thus it is by no means only the laboratory animals themselves that will benefit from a wide circulation of this comprehensive and authoritative volume. Among them the laboratory mouse must presumably be reckoned the first, a t any rate on the basis of counting paws; nearly three- quarters of the animals used in British laboratories are mice. But when the advantages to different species are “weighted” to take account of other factors than mere numbers, probably the guinea-pig will turn out to be the chief gainer. The state of the pre-war laboratory guinea-pig had to be seen often to be believed-and for the results it furnished to be disbelieved. The im- provement is already enormous, and this is in no small measure due to the activities of the Laboratory Animals Centre (formerly the Laboratory Animals Bureau), one of the direct outcomes of the searching examination carried out during the war years into current conditions for producing and distributing laboratory animals.No doubt the combined efforts of the Bureau and UFAW will secure further continuous improvements to the benefit of animal and user alike; the joint editorship of this book, indeed, ensures that these improvements will be both morally acceptable and scientifically sound. A. L. BACHARACH7 04 BOOK REVIEWS [Vol. 83 SMITH, BSc., Ph.D., F.R.I.C. Pp. xiv $. 309. London: William Heinemann Medical Books Ltd. 1958. Price 45s. Many volumes on chromatography have now appeared in print, and interest in the applications of this technique is becoming wider each day.This may be partly because with this procedure we are enabled to identify microgram amounts of complex materials without any prior separation. I t is also because chromatographic technique is relatively simple and, to some extent, artistic, and, once the procedure has become familiarised, there is a constant challenge to apply the ideas to any new problems that arise. But it is probably in the biological sciences that most use is made of chromatography; it is with this field that Dr. Smith’s book deals mostly. Nevertheless, it is, in general, an excellent concise exposition of the present position in regard to the technique used in chromatography.At the same time, the key references are present for those who wish to delve more deeply into the fundamentals of the procedure. In the main, the book deals with the applications of paper chromatography ; it is actually a compilation of chromatographic applications to various biochemical subjects, and each chapter has a specialist author. The introductory chapters by Dr. Smith discuss the type of apparatus recommended in the book, its development and its limitations. The general principles of paper chromatography are outlined, mainly from the practical angle. These include such subjects as drop size, type of solvent, line of flow, location of agents and RF values, described in a fashion easy for the reader to comprehend, A description of de-salting and related technique is a further contribution by Dr.Smith. The importance of de-salting in the chromatography of organic compounds is fully discussed, together with the various techniques and apparatus used. Electrolytic de-salting, ion-exchange methods of analysis and solvent extraction are given consideration. The chapter on separation and identification of amino acids constitutes the most important part of the book. Types of solvents used, Tables of R, values for most amino acids with various solvents and the specific-location reagents for the chemical groupings in the amin42 acids make this chapter most valuable for reference by the practical worker. Here also are shown some of the abnormal chromatograms produced in certain pathological conditions wherein amino acid metabolism is disturbed. A chapter on the chromatography of indoles and imidazoles contains useful Tables of H, values and also photographs of many two-way chromatograms on .the subject.Purines and pyrimidines are also given full treatment, but it seems that the chapter on sugars is unnecessarily condensed. Keto- acids, phenolic acids and those in the citric cycle have more recently been the subject of chromato- graphic survey, and this work is well described. The chapter on barbiturates is of much interest to workers in the forensic field; Mr. Jackson of the Metropolitan Police Laboratory has contributed this section. The complexity of steroid chemistry and the need for research into the adrenal hormones has led to a search for new techniques, which have largely been based on chromatography. Some outline of this work is given by Mr.Edwards. The final chapters are on methods used for the investigation of new problems and also some model experiments for students. The biochemist will certainly find this book most helpful and workers in other fields, e.g., agriculture, may also profit from extending the applications given therein. R. F. MILTON CHROMATOGRAPHIC TECHNIQUES : CLINICAL AND 13IOCHEMICAL APPLICATIONS. Edited by XVOR MICRODIFFUSION ANALYSIS AND VOLUMETRIC ERROR. By EDWARD J. CONWAY, M.D., D.SC., F.R.I.C., F.R.C.P.I., F.R.S. Fourth Edition. Pp. xviii + 465. London: Crosby Lockwood & Son Ltd. 1957. Price 42s. In common with other scientific fields, analytical chemistry continues to expand a t an ever-increasing rate, and there is a steady trend txvards the application of small-scale methods of analysis in all branches of analytical chemistry.As a result of this, there has been a notable expansion of chemical literature during the last decade, and textbooks become virtually “out- dated” almost as soon as they are published. The task of the writer is consequently made more difficult in keeping abreast with developments, and textbooks are becoming more in the nature of reviews than accounts of the writers’ own experiences and appreciations, which are of greater value. This cannot be said of the book under review, which has retained its character of a treatise of the practical experiences of Professor Conway, now universally accepted by virtue of its previous editions.The technique of microdiffusion is an important tool that, although intended originally for application in the biochemical sphere, has many other uses when small-scale (milligram orDec., 19581 BOOK REVIEWS 705 microgram scale) methods of analysis are essential. In the same way, Professor Conway’s treatment of volumetric error is of value to both the student and the analyst. In this latest edition, Professor Conway has extended the text to include many new methods and applications that have been advanced during the past decade and also describes new develop- ments in apparatus. For example, an up-to-date treatment of blood analysis includes the blood ammonium method; a description of methods for total nitrogen, glutamine and glutamic acid; diffusion methods for determination of cyanide, sulphide, phenols, methanol and isopropanol and volatile poisons of toxicological interest.Methods for determining enzymes, such as mono- amine oxidase, and of histaminase and acetylcholinesterase have also been included. The deter- mination of formaldehydogenic steroids and of glycine by application of the well known chromo- tropic acid reaction with formaldehyde is described, glycine being determined by its reaction with ninhydrin to yield formaldehyde, which is separated by diffusion. Also of interest is the use of the diffusion technique for the determination of acetaldehyde, which is absorbed by semi- carbazide, the technique being used to determine indirectly lactic acid in blood and tissues. An up-to-date treatment of halogen determinations, including their determination in organic material, is given in the text, together with recent methods for determination of carbon monoxide.Improvements in the design of the standard microdiffusion units and components are described. Although this book is written generally for the biochemist, it is obviously one of great value to all analysts, since many of the methods described can be applied to a wide range of materials, for which reason the book should be accessible in every laboratory. G. INGRAM MANUAL OF ANALYTICAL METHODS RECOMMENDED FOR SAMPLING AND ANALYSIS OF ATMOSPHERIC CONTAMINANTS. By the Committee on Recommended Analytical Methods, American Conference of Government Industrial Hygienists. Loose leaf, viii f 50 pages (11 methods).Cincinnatti, Ohio : American Conference of Government Industrial Hygienists, 1958. Price $5.00. This Manual of eleven methods for the trace determination of ten toxic substances occurring in industrial atmospheres is the outcome of 13 years’ work by a series of committees, which have included a number of members well known in this specialised field of analysis. The work has been sponsored by the American Conference of Government Industrial Hygienists, and is comple- mentary to the toxicological surveys undertaken by this organisation, which lead to the annual publication of lists of threshold limits or maximal allowable concentrations. The Manual aims to provide industrial hygienists with approved procedures for the sampling and analysis of atmospheric contaminants. Minimal requirements have been established for approval; methods should be sufficiently sensitive to measure one-tenth of the threshold limit, the air-sampling rate and sample volume should not exceed specified values, and the precision should be such that the average deviation obtained by a t least ten collaborating analytical labora- tories is not greater than 10 per cent.This collaborative confirmation is one of the most notable features of this Manual, but it is not extended to cover the air-sampling procedure. Simplicity has not been a major consideration, and, unlike the well known methods issued originally by the Department of Scientific and Industrial Research and now continued by the Factory Department of the Ministry of Labour, the procedures require skilled personnel and considerable laboratory facilities.The chemical reactions used in these methods are well established, with the exception of that for arsenic, in which arsine produces a red colour with silver diethyldithiocarbamate in pyridine. Lead and mercury are determined by dithizone methods, and chlorinated hydrocarbons by reaction with sodium to liberate chloride ion, and then argentimetric titration. Other methods included in the Manual are for hydrogen sulphide (by titration), manganese, oxides of nitrogen (phenol- disulphonic acid) and parathion; there is both a colorimetric and a polarographic method for sulphur dioxide. I t is rather surprising that a titration method has been selected for formaldehyde when several good colorimetric procedures are available. The methods are clearly presented, and the accuracy, sensitivity and interferences are listed.It is to be hoped that some of the more common contaminants of industrial atmospheres, which are missing from the present Manual, will be the subject of the same systematic study, J. C. GAGE706 BOOK REVIEWS [Vol. a3 KUNSTSTOFF-, LACK- UND GUMMI-ANALYSE: CHEMISCHE UND INFRAROTSPEKTROSKOPICHE METHODEN. By Dr. rer. nat. DIETER HUMMEL. (Two Volumes.) Text Volume: Pp. 409; Volume of Plates: 183 plates (548 spectra). Munich: Carl Hanser Verlag. 1958. Price DM.148.00; 259s. This book, which deals with the analysis of synthetic polymers, natural resins and gums, is written from a rather novel angle. Although the older chemical methods, which have long been used in attempted characterisations of these substances, are described, the bias in this book is always towards the infra-red structure.In Part I, detailed methods of preparation of samples for infra-red test are given. Then the various resins and polymers are described, and very few natural or synthetic polymers are omitted, e g . , copal resin and cellulose as well as polythene and polytetra- fluoroethylene all find a place. In addition, the first part includes information about plasticisers, stabilisers and aids to vulcanisation. The second part gives practical examples of the infra-red spectra of the various natural resins, synthetic polymers and plasticisers that are described in the first part. There are several points of criticism. For example, (1) the author index to the first part is extremely unsatisfactory.Many of the names of joint authors of papers are omitted, and reference back from the index to the text of the book cannot be made without prolonged search. (2) In Part 11, it is desirable that the spectra of proprietary preparations should be reduced to a minimum and particularly so when the chemical composition of the synthetic resin is not given. (3) It is unlikely that the binding of Part 11, which contains the spectra, will stand up to the wear and tear of the laboratory bench. Nevertheless, the analyst in the plastics and allied industries will do well to provide himself with copies of these two parts, and particularly so if lie believes, as he should, that infra-red spectra of natural and synthetic resins will supplement his chemical work.The book is in two parts. J. HASLAM MISES AU POINT DE CHIMIE ANALYTIQUE PURE ET APPLIQU~E ET D’ANALYSE BROMATOLOGIQUE. Quatribrne Serie: Pp. vi + 209; Cinquibme Serie: Pp. iv + 161; Paris: Masson et Cie. Edited by J.-A. GAUTIER. Sixikme Serie: Pp. iv + 171. 2500 fr. ; 2600 fr. 1956; 1957; 1958. Price 2400 fr.; A further three issues, Nos. 4, 5 and 6, have appeared under this title since the last review. The general style and arrangements are similar to those of the first three issues. Two contributions are notable for their comprehensive survey of their author’s chosen field and extensive classified bibliography. These are an article on foreign substances in foods (in No. 4) and one on the examination of fruit juices (in No.!5). The fourth issue also contains competent articles on recent advances in chromatography of carbohydrates, the quantitative acetylation of hydroxyl groups and on methods of dealing with samples of perishable and unstable foodstuffs, with special reference to milk. On the other hartd, a brief account of coulometric titrations (in No. 5 ) with no bibliography is of little value to anyone wishing to pursue this subject further. In No. 4, the determination of total solids is dealt with a t length from both theoretical and practical standpoints. Drying in vacuo a t 70’ C is the favoured procedure. The biological testing for preservatives in wines is described in No, 5. One would conclude from the opening paragraph of this article that the author has strong feelings on this matter, but the statement that chemical and physical methods are always more sensitive, more precise and more specific than biological methods must be regarded as a far too sweeping assertion. In the 6th issue, Professor Duval describes the extensive thermogravimetric studies made by his school using the Chevenard thermobalance.The apparatus and technique are described in detail, and the results are summarised. Also worthy of note in this issue is an article on the analytical use of sodium tetraphenylboron and one on the techniques involved in the use of radioactive elements in chemical analysis. Two examples must suffice. Gas - liquid chromatography is briefly described in an article on the application of physico-chemical methods to the analysis of fats, but without any reference t o the original papers of James and Martin.The short account of the use of the thermal-conductivity cell (katharometer) as a detector in gas chromatography is only likely to mislead those who are The analysis of wines forms the subject of two ,articles. Several articles could be criticised on grounds of omission or of superficial treatment.Dec., 19581 BOOK REVIEWS 707 unfamiliar with this instrument. The published work of de Whalley and his co-workers is ignored in an article that purports to deal with the use of ion exchange and chromatography in the analysis of the products of the sugar refinery. The general impression remaining after reading these reviews is one of wide variation in the value of individual contributions.P. MORRIES SCIENTIFIC GLASSBLOWING. By E. L. WHEELER. Pp. xxii + 478. New York and London: In the preface, the author states that his aim is to provide not only a text-book for the beginner in glass blowing, but also a manual that will enable a glassblower to serve as a general laboratory technician or even t o “make of himself the research chemist’s co-worker.” This explains why rather less than half the content of this book is concerned with the manipulation of glass, but does not excuse the poor choice of title. The instruction in glassworking is pedestrian and within the scope of existing literature on the subject. Only some of the important charac- teristic properties of glass are mentioned, and these in cursory fashion. The bearing that these factors have on problems of annealing, strain, fracture, thermal shock and reliability of components is not explained a t all.Likewise, the strain-viewer is described, but the interpretation of strain- patterns is not attempted, even in simple terms. In short, this section of the book lacks the knowledge without which the student glassworker cannot master his medium. The treatment of this aspect of the subject is so weak that one doubts if the author himself has acquired the necessary understanding. The remainder of the book comprises chapters on the deposition of metals, purification of mercury, fractional distillation, high vacuum, metal working, electric heaters and miscellaneous equipment and procedure. Here is assembled a mass of information based largely on manu- facturers’ brochures and prior publications. Whether or not a trained glassworker should concern himself with these matters is debatable. His proper function is to visualise the scientist’s needs and employ his skill in translating them into the reality of useful glass apparatus. Done well, this alone will secure him an honourable place in the research team. Twelve pages are made available for the contents list, and room has been found for a very large number of illustrations. Disregarding simple errors in spelling and grammar, attention is directed to the following. Chapter VIII refers to Housekeeper’s work on copper seals. His name and date of publication are misquoted, and Fig. 5B on p. 168 mis- interprets his instructions. It is necessary to refer to an original paper to understand the function of the apparatus drawn incorrectly in Fig. 6 on p. 252. In the expression for pumping speed (p. 341) it should not be left to the reader to guess most of the units of measurement. At the end of Chapter XVI, Tables V and VI each have several errors, Table VII has one and Table VIII is too empirical to be considered seriously. Interscience Publishers Inc. 1958. Price $9.75; 75s. The editing and proof-reading do not measure up to the quality of book-production. However, many corrections are called for. C. H. SIMMS
ISSN:0003-2654
DOI:10.1039/AN9588300702
出版商:RSC
年代:1958
数据来源: RSC
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16. |
Publications received |
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Analyst,
Volume 83,
Issue 993,
1958,
Page 707-708
Preview
|
PDF (95KB)
|
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摘要:
Dec., 19581 BOOK REVIEWS 707 Publications Received TABLES OF INTERATOMIC DISTANCES AND CONFIGURATIOS IN MOLECULES AND IONS. Scientific Editor: L. E. SUTTON, M.A., D.Phil., F.R.S. Special Publication No. 11. Pp. 391. London: The Chemical Society. 1958. Price 42s.; $6.00. By G. F. MUGELE, BSc. (Eng.), A.M.I.C.E., A.M.I.W.E., and A. WISEMAN, BSc., A.R.I.C. Pp. x + 141. London: George Newnes Ltd. 1958. Price 21s. Papers presented a t the Sixtieth Annual Meeting of the American Society for Testing Materials, Atlantic City, N.J., June 18th, 1957. Philadelphia, Pa.: American Society for Testing Materials. 1958. Price 962.75. WATER TREATMENT. SYMPOSIUM ON SPECTROCHEMICAL ANALYSIS FOR TRACE ELEMENTS. Pp. vi + 79. ASTM Special Technical Publication No. 221. THE STRENGTHS OF CHEMICAL BONDS.By T. L. COTTRELL. Second Edition. Pp. x + 317. London : Buttenvorths Scientific Publications; New York : Academic Press Inc. 1958. Price 32s.; $7.00.708 PUBLICATIONS RECEIVED AUTOMATIC MEASUREMENT OF QUALITY IN P~ocrsss PLANTS. Proceedings of a Conference held a t Swansea, September 23rd to 26th, 19ti7, by the Society of Instrument Technology. Pp. xii + 320. London: Buttenvorths Scientific Publications; New York: Academic Press Inc. 1958. Price 50s.; $9.50. THE PERIODIC TABLE. By D. G. COOPER, B.Sc., F.R.I.C. Pp. x + 86. London: Butterworths Scientific Publications. 1958. Price 6s. 6d. CHROMATOGRAPHIE VON STERINEN, STEROIDEN UND VERWANDTEN VERBINDUNGEN. By R. NEHER. Pp. viii + 100. Amsterdam, New York arid Princeton: Elsevier Publishing Co.; London: D. Van Nostrand Co.Ltd. 1958. Price 16s. Pp. xiv + 361. Vienna: Springer-Verlag. 1958. Price 81s. 6d.; $11.85. Compiled at the Plant Pathology Laboratory of the Ministry of Agriculture, Fisheries and Food. Technical Bulletin N o . 1. Third Edition. Pp. x + l 2 6 . London: Her Majesty’s Stationery Office. 1958. Price 7s. London: Methuen & Co. Ltd.; New York: John Wiley & Sons Inc. Rules issued by certain Commissions of the Inter- national Union of Pure and Applied Chemistry. London: Butterworths Scientific Publications. 1958. Price 15s. T h i s volume contains Definitive Rules f o r !jection A : Hydrocarbons, and Section B: Funda- mental Heterocyclic Systems, issued by the Commisssion on the Nomenclature of Organic Chemistry of I . U.P.A.C. (“The I.U.P.A.C.1957 Rules”), Definitive Rules f o r Nomen- clature of Steroids issued by the Commissions on the Nomenclature of Organic Chemistry and the Nomenclature of Biological Chemistry of the I . U.P.A.C. (“The I.U.P.A.C. 1957 Rules for Nomenclature of Steroids”), and Tentative Rules for Nomenclature in the Vitamin B,, Field recommended by the Commission on the Nomenclature of Organic Chemistry of the I.U.P.A.C. By E. J. SHELLARD, B.Pharm., F.P.S., A.R.I.C., F.L.S. London: Pitman Medical Publishing Co. Ltd. 1958. Price 15s. A Report of the British Iron and Steel Research Association. Pp. xii + 146. London: The Iron and Steel Institute. 1958. Price 37s. 6d. ELECTROANALYTICAL CHEMISTRY. By JAMES J . LINGANE, B.Chem., Ph.D. Second Edition. Pp. xiv f 669. New York and London: Interscience Publishers Inc. 1958. Price $14.50; 109s. CALEXDAR OF THE PHARMACEUTICAL SOCIETY 01’ GREAT BRITAIN 1958-1959. Pp. vi + 306. London: The Pharmaceutical Press. 1958 Price 20s. AN INTRODUCTION TO PATHOLOGY. By G. PAYLING WRIGHT, D.M., F.R.C.P. Third Edition. Pp. xii + 660. 1958. Price 45s. QUANTITATIVE ORGANISCHE MIKROANALYSE (PREGI, - ROTH). Seventh Edition. By Dr. H. ROTH. SPECIFICATIONS AND METHODS OF ANALYSIS FOR CERTAIN PESTICIDES. BIOLOGICAL LABORATORY DATA. NOMENCLATURE OF ORGANIC CHEMISTRY. By L. J. HALE, Ph.D. Pp. x + 132. 1958. Price 15s. Pp. vi + 92. EXERCISES IN THE EVALUATION OF DRUGS AND SURGICAL DRESSINGS. Pp. xviii + 158. THE DETERMINATION OF NITROGEN IN STEEL. Iron and Steel Institute Special Report No. 62. London, New York and Toronto: Longmans, Green & Co. Ltd.
ISSN:0003-2654
DOI:10.1039/AN9588300707
出版商:RSC
年代:1958
数据来源: RSC
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