Showing papers in "Analyst in 1971"
TL;DR: It was found that if 100 mg of tin(II) chloride alone were added instead of the tin( II) chloride-cadmium chloride reagent, only the release of inorganic mercury influenced the peak deflection of the potentiometer, thus permitting the selective determination of in organic mercury in the presence of methylmercury.
Abstract: A simple method for the determination of total mercury in biological samples contaminated with inorganic mercury and methylmercury is described The method is based on the rapid conversion of organomercurials first into inorganic mercury and then into atomic mercury suitable for aspiration through the gas cell of a mercury vapour concentration meter, by a combined tin(II) chloride-cadmium chloride reagent It was found that if 100 mg of tin(II) chloride alone were added instead of the tin(II) chloride-cadmium chloride reagent, only the release of inorganic mercury influenced the peak deflection of the potentiometer, thus permitting the selective determination of inorganic mercury in the presence of methylmercury It was possible first to release inorganic mercury then, after re-acidification of the reaction mixture, methylmercury, by adding the tin(II) chloride-cadmium chloride reagent and sodium hydroxide When total mercury and inorganic mercury were determined separately, the difference between results gave the methylmercury content of the sample
345 citations
88 citations
TL;DR: In this article, a method for the extraction of nitrate and nitrite from meat by heating at 80 °C for 10 minutes to coagulate the protein and inactivate nitrates and nitrites reductase activity and subsequently treating with alumina cream.
Abstract: A method has been developed for the extraction of nitrate and nitrite from meat by heating at 80 °C for 10 minutes to coagulate the protein and inactivate nitrate and nitrite reductase activity and subsequently treating with alumina cream. The latter treatment alone was used for the clarification of curing brines.A method for the reduction of nitrate to nitrite by shaking with cadmium has been developed that is quicker, as it takes 5 minutes, than column reduction, which requires 40 to 60 minutes. Quantitative recoveries of nitrate as nitrite were obtained.Methods of determining nitrate as nitrite involving the use of the diazo compounds formed between sulphanilic acid and each of the four coupling agents 1-naphthylamine, N-1-naphthylethylenediamine, 1-naphthylamine-7-sulphonic acid and 1-naphthol were investigated. N-1-Naphthylethylene-diamine is recommended because of the short time (10 minutes) required for maximum colour development.
80 citations
TL;DR: The results are given of an application of the method to a study of the problem of metal ingestion by children who have pica, which results in average sensitivity increases of seven times that obtained by a direct determination on the aqueous solutions.
Abstract: A method is described for the determination of eleven metals in a 1-ml solution of an oxidised blood sample. The metals iron, copper, bismuth, zinc, cadmium, lead, cobalt, nickel, manganese, strontium and lithium are selectively extracted into small (0·30 to 0·50 ml) volumes of isobutyl methyl ketone as their chelates or ion-association complexes, and are determined in the organic phases by atomic-absorption spectrophotometry. The enhancement effect of the organic solvent combined with the extraction and concentration of the metals results in average sensitivity increases of seven times that obtained by a direct determination on the aqueous solutions.The recovery of the metals added to blood is quantitative and, with two exceptions (lead and bismuth), a precision of better than 8 per cent. can be achieved at the 0·1 p.p.m. level.The results are given of an application of the method to a study of the problem of metal ingestion by children who have pica.
63 citations
TL;DR: In this article, an automated method for the determination of ammonium in 2 N potassium chloride soil extracts is described, based on the indophenol blue method following a dialysing step.
Abstract: An automated method is described for the determination of ammonium in 2 N potassium chloride soil extracts. The determination is based on the indophenol blue method following a dialysing step. As little as 0·03 mg 1–1 of ammonium-nitrogen can be determined. The recoveries have been investigated for a number of different soil types and satisfactory results were obtained. Determinations can be carried out at the rate of thirty samples per hour.
60 citations
TL;DR: In this article, the effect of many cations and anions on the procedures has been investigated, including the elimination of the important interference caused by plutonium, and the applicability of the methods evolved has been demonstrated by the comparative analysis of a series of international secondary uranium ore standards and some other low-content uranium ores that have been analysed by independent chemical methods.
Abstract: The determination of uranium(VI) has been carried out by extraction-spectrophotometric methods based on the use of tributyl phosphate dissolved in isobutyl methyl ketone and trioctylphosphine oxide in benzene. Arsenazo III is used as the metallochromic reagent in a medium buffered with monochloroacetic acid-sodium monochloroacetate. The effect of many cations and anions on the procedures has been investigated, including the elimination of the important interference caused by plutonium.The applicability of the methods evolved has been demonstrated by the comparative analysis of a series of international secondary uranium ore standards and some other low-content uranium ores that have been analysed by independent chemical methods. The trioctylphosphine oxide-benzene-arsenazo III procedure, which has been shown to be greatly superior to the other methods, permits the direct determination of uranium(VI) in the presence of plutonium when the uranium-to-plutonium ratio is greater than 0·2 per cent. The method has also been found suitable for the determination of uranium in monazitic sands, rare earth concentrates, zirconium-bearing materials and phosphoric acid solutions of the type used for the leaching of low-grade uranium ores.
58 citations
TL;DR: In this article, a sensitive colorimetric method has been developed for the determination of trace amounts of sulphide in condensed steam, which can be obtained "on site" by a simple visual titration of a reference solution with a methylene blue solution.
Abstract: A sensitive colorimetric method has been developed for the determination of trace amounts of sulphide in condensed steam. For precise work the colour produced by NN-diethyl-p-phenylenediamine in the presence of iron(III) ions is measured spectrophotometrically covering the range 0·5 to 100 µg of sulphide-sulphur; the standard deviations at the 100 and 1·0-µg levels are about 3 and 0·08 µg, respectively. Reasonably accurate results over the range 0·5 to 25 µg of sulphide-sulphur can be obtained “on site” by a simple visual titration of a reference solution with a methylene blue solution. The NN-diethyl-p-phenylenediamine was shown to be superior to the dimethyl homologue normally used, and its use does not appear to have been reported previously. Methods of sampling and the effect of sulphite are also discussed.
54 citations
TL;DR: In this article, a method for the determination of low levels of mercury by using atomic fluorescence in conjunction with the cold vapour technique is described, and shows significant advantages over the corresponding absorption technique.
Abstract: A method for the determination of low levels of mercury by using atomic fluorescence in conjunction with the cold vapour technique is described, and shows significant advantages over the corresponding absorption technique.
45 citations
TL;DR: Urine samples that have been cold-digested by potassium permanganate-sulphuric acid mixture overnight are analysed in apparatus consisting of an automatic sample changer, pumps for transferring the sample solution to a purgation tower and adding tin(II) chloride solution, which reduces mercury( II) to metallic mercury, and a spectrophotometer.
Abstract: Urine samples that have been cold-digested by potassium permanganate-sulphuric acid mixture overnight are analysed in apparatus consisting of an automatic sample changer, pumps for transferring the sample solution to a purgation tower and adding tin(II) chloride solution, which reduces mercury(II) to metallic mercury, and a spectrophotometer. The mercury vapour is liberated from the solution in the tower by a flow of nitrogen and then taken through the absorption cell in the spectrophotometer where the light absorption at a wavelength of 253·7 nm is continuously recorded. After completion of the purgation, the mercury-free solution is transported back to the original tube in the sample changer by reversing the pumps, and the next analysis is started. The mercury content in the sample is calculated from standard graphs drawn from results with known amounts of mercury. Sixty digested samples, each containing 1 ml of urine, are analysed in about 2 hours without any manual work or supervision. In each sample about 1 ng of mercury can be detected, but normally the working range for urine samples is 0 to 400 ng ml–1 of mercury(II). The analysis can be applied to biological or any other samples that can be digested in a similar manner.
45 citations
TL;DR: In this paper, a procedure for determining yttrium, europium, terbium, dysprosium, holmium, thulium, ytterbium and lutetium in zirconium and calcium rare earth silicates by atomic-absorption spectroscopy was described.
Abstract: A procedure is described for determining yttrium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium in zirconium and calcium rare earth silicates by atomic-absorption spectroscopy, which involves the use of a lanthanum suppressor and has potential applications to other minerals containing these interferences. Although many of the associated ingredients are found to interfere, the addition of lanthanum overcomes these problems in many instances. Sensitivities and detection limits found with the proposed procedure are given for each element.
36 citations
TL;DR: In this paper, a pyrohydrolytic method for the determination of fluorine in rocks and minerals is described, where the sample is heated with a three-component flux in a stream of moist air, and the liberated hydrogen fluoride is absorbed into an alkaline solution.
Abstract: A rapid pyrohydrolytic method, with simple apparatus, is described for the determination of fluorine in rocks and minerals. The sample is heated with a three-component flux in a stream of moist air, and the liberated hydrogen fluoride is absorbed into an alkaline solution. The recovered fluorine is determined either colorimetrically or by means of a fluoride-specific electrode. The method is suitable for determining fluorine at concentrations down to about 50 p.p.m.
TL;DR: A method has been developed for the extraction and determination of sub-microgram amounts of nicotine in blood and has been applied to the measurement of nicotine levels found in the blood of smokers while smoking cigarettes.
Abstract: A method has been developed for the extraction and determination of sub-microgram amounts of nicotine in blood. It involves steam distillation of the nicotine followed by solvent partition and column-chromatographic clean-up. The final solution of nicotine in ethanol is injected directly on to the column of a gas-liquid chromatograph fitted with a flame-ionisation detector. The method can be used to determine down to 1 ng of nicotine, and has been applied to the measurement of nicotine levels found in the blood of smokers while smoking cigarettes.
TL;DR: In this article, the ratio between the quantity H = 10pH and the true hydrogen-ion concentration in solutions of fixed ionic composition was measured in alkaline solutions, and were in agreement with values previously determined in acidic solutions.
Abstract: Measurements of the ratio between the quantity H (= 10–pH) and the true hydrogen-ion concentration in solutions of fixed ionic composition have been made in alkaline solutions, and are in agreement with values previously determined in acidic solutions.
TL;DR: A method is described for the determination of zinc oxide fume in industrial atmospheres at concentrations up to 20 mg m–3 of zinc dioxide and the zinc is determined spectrophotometrically or visually with 4-(2′-thiazolylazo)resorcinol reagent.
Abstract: A method is described for the determination of zinc oxide fume in industrial atmospheres at concentrations up to 20 mg m–3 of zinc oxide. The fume is collected on a filter and dissolved in acid, and the zinc is determined spectrophotometrically or visually with 4-(2′-thiazolylazo)resorcinol reagent. The apparatus used is simple and the time required for a determination is about 20 minutes. A dynamic method for the generation of atmospheres of zinc oxide is also described.
TL;DR: Atomic-absorption spectroscopy is used to determine cobalt in plants and animal tissues after solvent extraction of the 1-nitroso-2-naphthol complex from an acidic solution of the sample, which is more sensitive than, and as accurate and precise as, a colorimetric procedure involving nitro so-R salt.
Abstract: Atomic-absorption spectroscopy is used to determine cobalt in plants and animal tissues after solvent extraction of the 1-nitroso-2-naphthol complex from an acidic solution of the sample. The solvent is evaporated and the complex is dissolved in ethyl methyl ketone for aspiration. The method is more sensitive than, and as accurate and precise as, a colorimetric procedure involving nitroso-R salt, and is much less tedious.Cobalt can be determined in the range 0·05 to 1 µg in the final 1-ml sample solution (corresponding to 0·05 to 1 p.p.m.). With a 5-g sample from 0·01 to 0·2 p.p.m. of cobalt in samples (dry matter) can be determined. The method can, therefore, be applied readily to pasture samples containing 0·1 p.p.m. of cobalt and less, levels that are considered likely to cause deficiency in ruminants. At 0·07 p.p.m. of cobalt the coefficient of variation is 14 per cent. At higher concentrations (0·14 p.p.m.) of cobalt in pasture and liver samples the coefficients of variation are 11 and 6 per cent., respectively.
TL;DR: In this paper, it was shown that the oxalate method gives results that are comparable with those of the iron(II) method with the addition of either Cu2+ or Fe3+ in the reagent solutions.
Abstract: Of the various methods available for the determination of active oxygen in managanese dioxide, the oxalate method is preferred because of its simplicity and reproducibility. However, it tends to give higher results than the iron(II) and Bunsen methods, the discrepancies being greater with synthetic materials than with ores. In confirmation of the work of other authors it has been shown that there is a Mn2+ catalysed loss of oxalate that causes the high results. It is concluded that the loss is caused by oxidation by oxygen dissolved in the reagent solutions. With the addition of Cu2+ or Fe3+, the oxalate method gives results that are comparable with those of the iron(II) method. The stabilisation of oxalate with Fe3+ has been used to speed up the time taken to dissolve samples by boiling them under reflux.
TL;DR: Iodine and bromine have been determined in some biological materials by neutron activation analysis as discussed by the authors, and they are extracted from irradiated samples with a 5 per cent. solution of trioctylamine in xylene.
Abstract: Iodine and bromine have been determined in some biological materials by neutron activation analysis. These elements are extracted from irradiated samples with a 5 per cent. solution of trioctylamine in xylene, first the bromine being back-extracted with N sodium nitrate solution and then the iodine being back-extracted with N ammonia solution. The extraction yield is about 94 per cent. for iodine and about 86 per cent. for bromine. The limit of detection is about 0·01 µg for iodine and about 0·1 µg for bromine.The precision of the method is about ±6 per cent. for both elements for concentrations exceeding 0·1 p.p.m.
TL;DR: In this article, a method that involves coulometric titration of carbon dioxide absorbed in a partially aqueous medium is described for the precise determination of carbon in steel, which does not depend on empirical standardisation and the use of high-vacuum systems and inflammable titrants is avoided.
Abstract: A method that involves coulometric titration of carbon dioxide absorbed in a partially aqueous medium is described for the precise determination of carbon in steel. It does not depend on empirical standardisation and the use of high-vacuum systems and inflammable titrants is avoided. The apparatus used is inexpensive and the technique is simple. The application of appropriate instrumentation could provide a routine control method of high precision.The analytical performance of the method compares well with that of other techniques considered suitable for reference analysis; 95 per cent. confidence limits of ±0.0007 per cent. of carbon at the 0·05 per cent. of carbon level of 0·008 per cent. of carbon at the 0·9 per cent. of carbon level were obtained in this laboratory.
TL;DR: In this paper, a self-indicating system was proposed to increase the electrophoretic mobility of charged polysaccharides by increasing the amount of sodium carbonate added in the dyeing process.
Abstract: Polysaccharides that have been previously treated with reactive dyestuffs can be separated within 1 to 3 minutes by electrophoresis on PhoroSlides at potential gradients of 40 to 56 V cm–1. In addition to providing the required self-indicating system, dyeing increases the electrophoretic mobility of charged polysaccharides. The difficulty experienced in dyeing polysaccharides that have small proportions of primary hydroxyl groups (e.g., plant gums, pectin, alginic acid and sulphated polysaccharides) can be overcome by increasing the amount of sodium carbonate added in the dyeing process.
TL;DR: A method based on this reaction is described for the quantitative determination of taurine and it is applied to the determination of this amino-acid in rat brain after passage of the tissue extract through ion-exchange resins.
Abstract: Taurine is made to react with o-phthalaldehyde in the presence of urea and phosphate ions, and on acidifying the mixture with acetic acid a purple product is formed with an extinction maximum at 560 nm. A method based on this reaction is described for the quantitative determination of taurine and it is applied to the determination of this amino-acid in rat brain after passage of the tissue extract through ion-exchange resins. The effect of other amino-acids on the accuracy of the method is discussed.
TL;DR: NN-Dimethylcasein is used as substrate in an automatic method for the determination of proteolytic enzymes in washing products and airborne dust samples because of its high sensitivity, which is of particular value in dust analysis.
Abstract: NN-Dimethylcasein is used as substrate in an automatic method for the determination of proteolytic enzymes in washing products and airborne dust samples. Amino-acids formed by reaction with the enzyme are caused to react with 2,4,6-trinitrobenzenesulphonic acid to form stable, coloured Meisenheimer complexes. As NN-dimethylcasein does not react with trinitrobenzenesulphonic acid there is not need to remove excess of substrate before colour development, and the enzyme digestion and colour reactions can be conducted simultaneously. This leads to high sensitivity, which is of particular value in dust analysis and allows the use of a simple trouble-free manifold.
TL;DR: A critical examination of the underlying chemistry has led to a modified procedure in which the time required for analysis has been reduced from 3·5 hours to 17 minutes, and the procedure is suitable for the quantitative determination of ammonia (and amino-acids) in other natural waters.
Abstract: Strickland and Parsons have described a method for determining ammonia (and amino-acids) in sea water. This method, in which ammonia is first oxidised to nitrite with sodium hypochlorite, was found to be very time consuming and often imprecise. The results of a critical examination of the underlying chemistry have led to a modified procedure in which the time required for analysis has been reduced from 3·5 hours to 17 minutes. The modified procedure gave a coefficient of variation of 1·6 per cent. from the analysis of thirteen replicate aliquots of a sample of sea water containing approximately 20 µg 1–1 of ammonium-nitrogen, and hence is suitable for determining ammonia concentrations in the order of 0 to 200 µg 1–1. The response for 1 µg 1–1 of ammonium-nitrogen, in either sea water or de-ionised water, was equivalent to an optical density change of 1·6 × 10–3 per cm of solution. The procedure is also suitable for the quantitative determination of ammonia (and amino-acids) in other natural waters.
TL;DR: In this paper, a modified procedure for the extraction of perchlorate with brilliant green into benzene is described, which gives a reproducible and nearly quantitative recovery of low blanks (A= 0·02 to 0·04).
Abstract: A modified procedure for the extraction of perchlorate with Brilliant green into benzene is described, which gives a reproducible and nearly quantitative recovery of perchlorate (apparent Iµ640nm= 94 000) and low blanks (A= 0·02 to 0·04). Studies on the use of untreated glassware, silanised glassware and polypropylene-ware have indicated that adsorption effects are not very important. Nevertheless, the standard and sample solutions should be treated in the same vessels and the absorbance measurements made in quartz cells.Brilliant green perchlorate can be extracted from aqueous solutions in the pH range 3 to 6·5, but the solutions should be buffered at a constant pH value.The procedure has been applied successfully to the determination of perchlorate in samples of potassium chlorate.
TL;DR: In this paper, a modified version of the Halphen test was applied to oils containing a wide range of concentrations of total cyclopropenoid material in the component fatty acids and the use of pressurised capsules for carrying out the reaction with reduced loss of solvent has proved advantageous, as flatter peaks are obtained when optical absorption is plotted against time.
Abstract: An application to cottonseed oils of a quantitative version of the Halphen test for the determination of cyclopropenoid material has been published by other workers, but for other oils containing higher levels of cyclopropenoids, although the absorption at the 495 nm peak is linearly related to the concentration of each oil examined, the relationship differs among the oils. However, transmethylation of oil before applying the Halphen reaction has been found to give results that are in better agreement with titration with hydrogen bromide for oils with widely differing cyclopropenoid content. The use of pressurised capsules for carrying out the reaction with reduced loss of solvent has proved advantageous, as flatter peaks are obtained when optical absorption is plotted against time. The application of the modified technique to oils containing a wide range of concentrations of total cyclopropenoid material in the component fatty acids is described and discussed.
TL;DR: In this paper, an alternative method for the determination of molybdenum is presented, which involves the use of a perchloric-phosphoric-sulphuric acid mixture to retain the tungsten in solution.
Abstract: Interferences in the absorption of chromium and molybdenum in steels are overcome in the nitrous oxide-acetylene flame by using perchloric acid as the solvent. The method is rapid and suitable for any level of chromium or molybdenum found in steels and other metallic alloys. An alternative method for the determination of molybdenum is necessary when the tungsten concentration exceeds 0·5 per cent.; this involves the use of a perchloric-phosphoric-sulphuric acid mixture to retain the tungsten in solution. A difference read-out technique to obtain good precision for high levels of chromium is described.
TL;DR: A gas-chromatographic method for the determination of trace amounts of a toxic impurity, 2,3,7,8-tetrachlorodibenzo-p-dioxin, is described.
Abstract: A gas-chromatographic method for the determination of trace amounts of a toxic impurity, 2,3,7,8-tetrachlorodibenzo-p-dioxin, is described. A purified extract of the sample was subjected to gas chromatography on a column containing either 2 per cent. of OV-17 on Diatomite CQ or 1 per cent. of Hi-Eff 8 BP on Gas-Chrom Z with electron-capture detection. 2,4,5-Trichlorophenoxyacetic acid and 2,4,5-trichlorophenol were purified by chromatography of an ether extract of the sample on a column of alumina, followed by shaking with sulphuric acid. For 2,4,5-trichlorophenoxyacetic acid esters and formulations, saponification and chromatography on a Celite-sulphuric acid column, followed by chromatography on a column of alumina, were necessary.Recoveries of 2,3,7,8-tetrachlorodibenzo-p-dioxin ranged from 89 to 98 per cent., and the standard deviation of the method at a level of 0·3 p.p.m. was 0·03 p.p.m. The limit of detection was about 0·05 p.p.m.
TL;DR: In this article, the determination of manganese, nickel, chromium, molybdenum, copper, vanadium, cobalt, titanium, tin, aluminium and lead in steel by a single dissolution based on perchloric acid, is described.
Abstract: The determination of manganese, nickel, chromium, molybdenum, copper, vanadium, cobalt, titanium, tin, aluminium and lead in steel by a direct atomic-absorption method, which involves a single dissolution based on perchloric acid, is described. The scheme effects considerable savings in time compared with traditional methods, and is of comparable accuracy.The serious depressive interferences caused by iron on the response of some elements are overcome in the nitrous oxide-acetylene flame, and minor effects are corrected for by inclusion of iron in calibration standards. No other inter-elemental interferences were encountered in perchloric acid based solutions in the presence of iron.Silicon and tungsten, which are not retained in solution in this scheme, are determined after a separate dissolution of the sample.Results obtained with British Chemical Standard steels are tabulated, and accuracies discussed.
TL;DR: In this paper, a method for the extraction, separation and determination of pentachlorophenol or its sodium salt in softwoods and preservative solutions is described, and the effect of time and temperature on the oxidation-condensation reaction of 4-aminophenazone with Pentachlorphenol has been investigated.
Abstract: A method is described for the extraction, separation and determination of pentachlorophenol or its sodium salt in softwoods and preservative solutions. Pentachlorophenol is separated from lower chlorophenols and wood extractives by adsorption on to Bio-Rad AG 2-X8 anion-exchange resin, eluted with glacial acetic acid, extracted into chloroform, and determined by spectrophotometric measurement of the blue 4-aminophenazone-pentachlorophenol complex.The effect of time and temperature on the oxidation-condensation reaction of 4-aminophenazone with pentachlorophenol has been investigated.The procedure is particularly useful for the study of the distribution of pentachlorophenol-containing preservatives in wood.
TL;DR: In this paper, a method for the quantitative extraction of acrylamide from water-treatment grade polymers and copolymers is described, which is performed by shaking the polymer with methanol-water (80 + 20) for 24 hours.
Abstract: A method is described for the quantitative extraction of acrylamide from water-treatment grade acrylamide polymers and copolymers. The extraction is performed by shaking the polymer with methanol-water (80 + 20) for 24 hours. An improved gas-chromatographic method has been developed for analysing these extracts and can be conveniently used at levels down to 0·0004 per cent. of acrylamide in polymer; 0·05 per cent. of acrylamide in polymer can be determined with a relative standard deviation of ± 4 per cent.Only two of the polymers tested contained materials that interfered in the gas-chromatographic determination. A thin-layer chromatographic clean-up technique is described, which enables these polymers to be analysed by gas chromatography with no interference.