Showing papers in "Analyst in 1970"
TL;DR: In this article, the AutoAnalyzer is used for determining nitrate and nitrite in fresh and sea water and in soil extracts with the help of a modified manual procedure by Wood, Armstrong and Richards, which consists in reduction of nitrate with copperised cadmium and, with the nitrite thus produced, diazotisation of sulphanilamide, the product being coupled with N-1-naphthylethylenediamine to form a highly coloured azo dye, which is measured at 520 nm.
Abstract: Automatic methods for determining nitrate and nitrite in fresh and sea water and in soil extracts with the AutoAnalyzer are described, together with details of the analytical systems. The methods are based on a modification of the manual procedure by Wood, Armstrong and Richards, which consists in reduction of nitrate with copperised cadmium and, with the nitrite thus produced, diazotisation of sulphanilamide, the product being coupled with N-1-naphthylethylenediamine to form a highly coloured azo dye, which is measured at 520 nm. The methods are capable of analysing twenty samples per hour.
551 citations
TL;DR: In this paper, a long life, rapid response, calcium-sensitive electrode that nearly follows Nernstian behaviour between 0° and 48° C has been made by incorporating a liquid ion exchanger into a poly(vinyl chloride) matrix.
Abstract: A long life, rapid response, calcium-sensitive electrode that nearly follows Nernstian behaviour between 0° and 48° C has been made by incorporating a liquid ion exchanger into a poly(vinyl chloride) matrix. Selectivities have been obtained by several methods for Zn2+, Mg2+, Ba2+, Na+, K+ and H+. The determination of calcium in tap water with the PVC electrode and by a standard EDTA method is discussed.
433 citations
TL;DR: Thirty-nine blood samples with lead concentrations ranging from 19 to 245 µg per 100 ml were analysed by the method described and by automated colorimetry involving the use of dithizone, and the correlation coefficient between the results was 0·989.
Abstract: The concentrations of lead in 10-µl samples of whole blood are accurately determined in less than 5 minutes by atomic-absorption spectrophotometry. After partial oxidation with hydrogen peroxide in micro crucibles made from nickel foil, the samples are volatilised, by using an air-acetylene flame, into a nickel absorption tube situated in the flame.The sensitivity of the method is 1 × 10–10 g of lead per 1 per cent. absorption at 283·3 nm, and the standard deviation is ±4 per cent. at the 3-ng level.Thirty-nine blood samples with lead concentrations ranging from 19 to 245 µg per 100 ml were analysed by the method described and by automated colorimetry involving the use of dithizone. The correlation coefficient between the results of both methods was 0·989.
293 citations
TL;DR: An account is given of the development of a system making maximum use of automated equipment in the routine determination of nitrogen in biological samples when the desired order of precision is better than 1 per cent.
Abstract: An account is given of the development of a system making maximum use of automated equipment in the routine determination of nitrogen in biological samples when the desired order of precision is better than 1 per cent. and the expected number of analyses is greater than 100 per day.An automatic digestion unit made by Technicon Instruments Company Ltd. tested for liquids did not achieve the accuracy desired. Results for biological fluids with this digestor tended to be low on occasion by up to 5 per cent. Recovery of nitrogen from solutions of the pure compounds creatine and arginine was as low as 70 per cent. and alterations in the digestion mixture and digestor heating conditions did not materially improve recovery. For this reason all samples were subsequently digested by a standard Kjeldahl method before automated determination of ammonia in the diluted digests.Studies were made of the indophenol-blue reaction used in the automated system for determining ammonia in aqueous solution. Conditions were most stable when the reaction coil was maintained at 22°± 1° C and dwell time in the coil was about 3 minutes. Effects of mineral content of test solutions, sampling rate and sampler cam irregularities on the reliability of results were investigated.Results for nitrogen determined in acid digests by the automated procedure and by a standard distillation method showed close agreement.The use of an I.B.M. 1130 computer allowed calculation of results to be carried out in half the time taken when using an electronic desk calculator.
285 citations
TL;DR: In this article, gas chromatography of the component fatty acids with added internal standard can be used to determine a wide variety of neutral and polar lipids, after separation by thin-layer chromatography, if precautions are taken to minimize losses.
Abstract: Gas chromatography of the component fatty acids with added internal standard can be used to determine a wide variety of neutral and polar lipids, after separation by thin-layer chromatography, if precautions are taken to minimise losses. Results can be expressed in terms of the relative amounts of fatty acids contained by the lipids or the actual weights and molar amounts of the lipid classes can be calculated by applying readily derived factors. The procedure is at least as accurate as others in current use and has the additional merit of allowing simultaneous determination of lipid and fatty acid composition.
182 citations
TL;DR: In this article, the use of a commercial anion exchange electrode for the rapid determination of nitrate in plant material and in non-saline soils and waters was proposed, which gives better recovery and reproducibility than the Devarda method.
Abstract: The use of a commercial anion-exchange electrode permits the rapid determination of nitrate in plant material and in non-saline soils and waters. The buffer used eliminates chloride, nitrite and organic anion interferences. The proposed method gives better recovery and reproducibility than the Devarda method.
142 citations
141 citations
TL;DR: A rapid and sensitive method based upon wet digestion of 1-ml samples of urine by potassium permanganate-sulphuric acid at room temperature overnight, reduction of mercury(II) to metallic mercury by tin(II), evaporation of mercury vapour from the solution by an air current atRoom temperature and determination of mercury by cold-vapour atomic-absorption measurement at 253·7 nm.
Abstract: A rapid and sensitive method for the determination of mercury in urine is described. It is based upon wet digestion of 1-ml samples of urine by potassium permanganate-sulphuric acid at room temperature overnight, reduction of mercury(II) to metallic mercury by tin(II), evaporation of mercury vapour from the solution by an air current at room temperature and determination of mercury by cold-vapour atomic-absorption measurement at 253·7 nm. Mercury determination on digested samples can be carried out at the speed of about 1 sample minute–1. The amounts of chemicals and of glassware needed are much less than those required for the dithizone method. Detection limit is 2 ng of mercury in 1 ml of urine. The proposed method has been compared with dithizone analysis in a series of urine samples with fairly good results.Chemical interference from various substances is discussed.
125 citations
TL;DR: In this article, a method for converting ammonium sulphate into nitrogen gas for isotopic analysis on a mass spectrometer is described, which is faster and more convenient than previous techniques.
Abstract: A method, which is faster and more convenient than previous techniques, is described for converting ammonium sulphate into nitrogen gas for isotopic analysis on a mass spectrometer. The dry ammonium sulphate sample is contained in a small screw-topped vial, in which it can be stored pending analysis. This vial can be coupled with a neoprene O-ring to a special assembly, evacuated, and the sample oxidised with air-free hypobromite solution from a reservoir in the assembly. By using this procedure the usual inconvenience of de-greasing ground-glass joints on sample tubes is avoided, the difficulty of storing samples prior to analysis is overcome and the de-gassing of solutions prior to the conversion of each sample into nitrogen gas is eliminated. The procedure is particularly suitable when many hundreds of samples are to be analysed.
118 citations
TL;DR: Application of the technique to the study of plasma hydroxyproline levels in the domestic fowl is described, and comparison with isotope-dilution analysis demonstrates the lack of gross interference.
Abstract: The adaptation of a manual technique for hydroxyproline determination to the AutoAnalyzer is described. The method can be used to determine standard solutions to within 2·6 per cent. and to deal with successive concentration differences of up to 10 µg ml–1. The concentration range for optimum accuracy is 2·5 to 15·0 µg ml–1. Application of the technique to the study of plasma hydroxyproline levels in the domestic fowl is described, and comparison with isotope-dilution analysis demonstrates the lack of gross interference.
89 citations
TL;DR: In this article, a method of titration is developed, in which titrations are carried out by adding titrant stepwise in equal volumes to the sample, with measurement of potential after each addition.
Abstract: A method of titration has been developed, in which titrations are carried out by adding titrant stepwise in equal volumes to the sample, with measurement of potential after each addition. This method is well suited for automatic titrations, for example, in biochemical and process control analysis.
TL;DR: In this paper, a simple rapid fusion technique, in which lithium metaborate is used as the fluxing medium, has been developed for the analysis of mineral silicates, coal ash, furnace deposits and other related materials.
Abstract: A simple rapid fusion technique, in which lithium metaborate is used as the fluxing medium, has been developed for the analysis of mineral silicates, coal ash, furnace deposits and other related materials. A single fusion, followed by dissolution in dilute nitric acid, allows the major constituents of the samples to be determined by atomic-absorption spectrophotometry within the following ranges: SiO2 5 to 80 per cent., Al2O3 2 to 60 per cent., TiO2 0·5 to 5 per cent., Fe2O3 2 to 60 per cent., CaO 1 to 40 per cent., MgO 1 to 40 per cent., Na2O 0·5 to 20 per cent. and K2O 0·1 to 10 per cent., with a precision comparable with that of conventional methods used for silicate analysis.
TL;DR: The photo-oxidation method described by Armstrong, Williams and Strickland for determining total phosphorus and nitrogen in sea water has been adapted for analysis of fresh-water samples and extended to include the determination of total iron.
Abstract: The photo-oxidation method described by Armstrong, Williams and Strickland for determining total phosphorus and nitrogen in sea water has been adapted for analysis of fresh-water samples and extended to include the determination of total iron. The samples are subjected to ultraviolet irradiation in a photochemical reactor consisting of a high pressure mercuryarc lamp, a reactor body with twenty-four fused silica sample tubes and a cooling fan. Organically combined phosphorus and iron are converted into orthophosphate and iron(III) ions in the presence of acid and excess of oxygen after an irradiation time of 1 hour. Organonitrogen compounds and ammonia in solutions with pH range 6·5 to 9 are oxidised to nitrate and nitrite after 4 hours' irradiation in the presence of excess of oxygen, which excess is ensured by addition of a few drops of 30 per cent. hydrogen peroxide solution.
TL;DR: A rapid and versatile method for the determination of sulphur in biological materials based on the stoicheiometric combination of mercury( II) and sulphur(II) with an acetone-dithizone indicator is described, which has a wide range and is less subject to interference.
Abstract: A rapid and versatile method for the determination of sulphur in biological materials based on the stoicheiometric combination of mercury(II) and sulphur(II) with an acetone-dithizone indicator is described. Although slightly less sensitive than some other micro methods it has a wide range and is less subject to interference.Precautions are suggested for total sulphur determination of samples with a high sulphate-sulphur concentration. Convenient procedures for the determination of total sulphur, total sulphate-sulphur, ester sulphate-sulphur, neutral sulphur and inorganic sulphate-sulphur are outlined, and also the possibility of combining liquid scintillation measurements of sulphur-35 with the same determinations.
TL;DR: The determination of carboxyhaemoglobin in blood and tissue taken at post-mortem is examined and the use of gas chromatography is found to be the method of choice.
Abstract: The determination of carboxyhaemoglobin in blood and tissue taken at post-mortem is examined. Spectrophotometric and differential protein precipitation techniques have been found to be unsatisfactory. The use of gas chromatography has been studied and is found to be the method of choice.
TL;DR: The results obtained showed that interferences from other anions were not great at levels commonly found in waters, and the specific-ion electrode appeared to be suited for routine analysis of well and surface waters with nitrate-nitrogen concentrations near or above the tolerance limit.
Abstract: An evaluation of the Orion selective-ion nitrate electrode for the determination of nitrate-nitrogen in waters is presented. The results obtained showed that interferences from other anions were not great at levels commonly found in waters. Recovery of added nitrate-nitrogen ranged from 83 to 105 per cent. However, nitrate-nitrogen values obtained by the electrode method on ground and surface-water samples were lower than those obtained by phenoldisulphonic acid and steam-distillation procedures. The specific-ion electrode appeared to be suited for routine analysis of well and surface waters with nitrate-nitrogen concentrations near or above the tolerance limit (10 mg l–1 of nitrate-nitrogen).
TL;DR: Results showed good agreement for a variety of samples, including heather, peat, clover, rye grass, mixed herbage, grain, straw, kale leaf, turnip, hay, silage, oak leaf and draff, indicating that almost all samples of vegetable origin can be reliably analysed for these seven elements by the proposed X-ray method.
Abstract: A method capable of wide application to the analysis of plant and faecal materials involving X-ray fluorescence spectrometry for magnesium, aluminium, silicon, phosphorus, sulphur, potassium and calcium is described. Ball milling the material for 10 minutes is sufficient to eliminate particle-size effects in samples diluted 1 + 1 with cellulose when compressed into discs. Inter-element effects are overcome by the use of correction lines and calibration for all elements is carried out with synthetic standards made by incremental addition.Most of the elements can be determined with coefficients of variation within ±1·0 per cent. at low concentrations. Results covering wide concentration ranges, obtained by X-ray and chemical methods, showed good agreement for a variety of samples, including heather, peat, clover, rye grass, mixed herbage, grain, straw, kale leaf, turnip, hay, silage, oak leaf and draff, thus indicating that almost all samples of vegetable origin can be reliably analysed for these seven elements by the proposed X-ray method.
TL;DR: In this paper, an automated procedure for the determination of ammonium and nitrate in soil extracts is described, which has wider application to the analysis of fertilisers and water samples.
Abstract: Automated procedures for the determination of ammonium and nitrate in soil extracts are described. Distillation of the extract with magnesium oxide, with subsequent determination of ammonia by the automated indophenol method, is used for ammonium. For ammonium plus nitrate, the nitrate is reduced with titanium(III) sulphate during distillation with magnesium oxide, and ammonia determined as before. The method has wider application, for example, to the analysis of fertilisers and water samples.
TL;DR: In this article, the phenolic hydroxyl content of bituminous coals has been determined by grinding the coal with pyridine in a vibratory agate ball mill, adding acetone as a thermometric indicator and titrating with a solution of potassium hydroxide in propan-2-ol.
Abstract: The phenolic hydroxyl content of bituminous coals has been determined by grinding the coal with pyridine in a vibratory agate ball mill, adding acetone as a thermometric indicator and titrating with a solution of potassium hydroxide in propan-2-olThe results indicate that phenolic hydroxyl accounts for 37 to 62 per cent of the organic oxygen, depending on the rank of the coal The individual values obtained are higher than those found for similar coals by potentiometric titration and by acetylation also for high carbon coals As with these other methods, the greatest proportion of phenolic oxygen was found in coals with about 85 per cent of carbon on the dry, mineral matter free basis (coal rank code No 500)The conclusion is drawn that the higher values obtained by the method described are more correct because the shape of the thermometric titration curves is characteristic of those of sterically hindered phenols, many of which it is known cannot be determined by acetylation or potentiometric titration
TL;DR: Two sensitive techniques are used for the determination of separated N-nitrosamines, namely differential polarography at acid pH and the release of nitrite on ultraviolet irradiation at alkaline pH in the manner of Daiber and Preussmann.
Abstract: The detection of small concentrations of N-nitrosamines in biological materials requires their prior selective extraction and concentration. A procedure is described for the separation of both volatile and non-volatile N-nitrosamines as a class, and their subsequent determination at low levels. N-Nitrosamines are adsorbed from aqueous solution on to activated carbon from which many can be desorbed to varying extents by refluxing with methanol. Two sensitive techniques are used for the determination of separated N-nitrosamines, namely differential polarography at acid pH and the release of nitrite on ultraviolet irradiation at alkaline pH in the manner of Daiber and Preussmann. The properties of N-nitrosamines and related compounds are compared and methods of differentiating between the groups of compounds are discussed.
TL;DR: A Technicon AutoAnalyzer is used for the colorimetric determination of molybdenum on the basis of its catalytic action on the potassium iodide-hydrogen peroxide reaction, which has been applied to the direct determination of the element in marine and fresh waters, milk and plant samples after dry ashing, and standard rock samples after alkaline fusion.
Abstract: A Technicon AutoAnalyzer is used for the colorimetric determination of molybdenum on the basis of its catalytic action on the potassium iodide-hydrogen peroxide reaction. The procedure is sensitive enough to determine 0·2 µg l–1 of molybdenum with no pre-concentration. The method has been applied to the direct determination of the element in marine and fresh waters, milk and plant samples after dry ashing, and standard rock samples after alkaline fusion. Chromate interference can be removed if necessary by evaporation of the sample solution to dryness with hydrogen peroxide. A correction must be applied if vanadium is present in 2-fold excess over molybdenum. Large variations in ionic strength have a marked effect on the determination.
TL;DR: In this article, a sensitive and selective chemiluminescent molecular emission method for the determination of sulphur and phosphorus is described, based on passing the test solutions into a cool reducing, nitrogen-hydrogen diffusion flame.
Abstract: A sensitive and selective chemiluminescent molecular-emission method for the determination of sulphur and phosphorus is described, based on passing the test solutions into a cool reducing, nitrogen-hydrogen diffusion flame. The resulting band emission at about 394 nm for sulphur and 520 nm for phosphorus is measured on a simple filter photometer. The limits of detection in aqueous solution by using conventional nebulising techniques with a heated chamber are 0·08 p.p.m. for sulphur and 0·007 p.p.m. for phosphorus.Most cations interfere by producing depressive matrix effects, but these can be overcome by a preliminary “batch” ion-exchange separation.For the determination of sulphur or phosphorus in organic matrices, the test solutions can conveniently be prepared by oxygen-flask combustion techniques. In a few instances it is possible to inject directly both aqueous and organic solutions into the flame.The method has been applied to the determination of sulphur in light distillates.
TL;DR: Anion-selective membrane electrodes have been applied to pharmaceutical analysis and the results obtained with the direct and indirect methods shows that they are in agreement.
Abstract: Anion-selective membrane electrodes have been applied to pharmaceutical analysis. Twenty-four halogenated pharmaceutical compounds were determined by both the direct and indirect potentiometric methods. The compounds investigated represented a wide range of pharmaceutical compounds used extensively in pharmacy and medicine. Determinations of the dissociated halides were carried out directly with no previous treatment but the undissociated halides were determined after applying Schoniger's method. Comparison of the results obtained with the direct and indirect methods shows that they are in agreement. The direct method can be adopted for rapid routine pharmaceutical analysis as it is easy to carry out.
TL;DR: In this article, a fully automatic titration system is described, which carries out transfer of the sample by pipette, and dilution, titration and washing of electrodes and titration vessels.
Abstract: A fully automatic titration system is described. The system carries out transfer of the sample by pipette, and dilution, titration and washing of electrodes and titration vessels. Titrations are performed by adding titrant stepwise in equal volumes to the sample, with recording of potential after each addition. These results are used to calculate equivalence points. The system has a loading capacity of 200 samples, and an analysis rate of up to 30 samples per hour.
TL;DR: Most procedures were suitable for use in the presence of other amino-acids, but sugars, urea and ammonium chloride caused considerable analytical losses.
Abstract: Thirty-eight methods for the spectrophotometric determination of hydroxyproline have been tested. The sensitivity of twenty-seven of these under routine conditions and their applicability for determining of hydroxyproline in synthetic and natural mixtures have been examined. Most procedures were suitable for use in the presence of other amino-acids, but sugars, urea and ammonium chloride caused considerable analytical losses. No single method was both sensitive and reproducible for use with synthetic mixtures and biological materials. The best results with any method were obtained by the identical treatment of all samples and by use of internal standards.
TL;DR: Two field methods are proposed for determining 2 to 10 p.p.m. of nitrogen dioxide in air using a liquid absorption method based on a Griess-Ilosvay reaction and a test-paper method which is unaffected by humidity and air.
Abstract: Two field methods are proposed for determining 2 to 10 p.p.m. of nitrogen dioxide in air; a liquid absorption method based on a Griess-Ilosvay reaction in which nitrogen dioxide recovery is improved by the incorporation of sodium arsenite in an alkaline absorption solution; and a test-paper method which is unaffected by humidity and air, that involves the use of papers, treated with p-anisidine and glycerol, with a storage life of 3 months. In both methods the apparatus required is easy to manipulate and transport and less than 10 minutes are required for a complete determination.
TL;DR: In this article, the spectrophotometric methods for determining rhenium and gold with Brilliant green have been re-examined in an investigation of the effects of purity of reagent and acidity on the precision and accuracy of results.
Abstract: The spectrophotometric methods for determining rhenium and gold with Brilliant green have been re-examined in an investigation of the effects of purity of reagent and acidity on the precision and accuracy of results. The perrhenate-Brilliant green ion-association complex is extracted from a solution at pH 6, and is unaffected by reagent purity. The extraction of the tetrachloroaurate(III)-Brilliant green ion-association complex is carried out from 0·5 M hydrochloric acid solution, however, and an impure reagent gives low recoveries. Procedures are recommended for the determination of rhenium and gold, and the purification of the reagent is discussed.
TL;DR: In this paper, a simple rapid method for the spectrophotometric determination of 0 to 2·5µg amounts of fluoride with an accuracy of better than 0·1 µg is described.
Abstract: A simple rapid method for the spectrophotometric determination of 0 to 2·5-µg amounts of fluoride with an accuracy of better than 0·1 µg is described. The stability and purity of the reagents have been studied and the optimum conditions for the sensitivity of the reaction established. The method can be applied to the analysis of aqueous solutions either directly or, if there are interferences, after a simple micro distillation.
TL;DR: In the procedure described, beryllium is isolated by solvent extraction in the form of a volatile, thermally stable chelate with trifluoroacetylacetone, and is then determined by gas chromatography with an electron-capture detector.
Abstract: The toxic nature of beryllium necessitates the use of a sensitive method for its detection. Present methods are not entirely satisfactory and the use of gas chromatography for the detection and determination of beryllium has been advocated. In the procedure described, beryllium is isolated by solvent extraction in the form of a volatile, thermally stable chelate with trifluoroacetylacetone, and is then determined by gas chromatography with an electron-capture detector. Results are presented for the determination of aqueous beryllium solutions and for beryllium contained in urine. Satisfactory results were obtained with both direct solvent extraction and solvent extraction after wet oxidation of the sample. The rate of excretion of beryllium by rats was measured by this method. The procedure is rapid, reliable and sensitive; the limit of detection is l ng ml–1.