Showing papers in "Analyst in 1976"
TL;DR: Freedom from interferences under the chosen experimental conditions as well as the good results obtained for recovery and precision indicate that the methods are suitable for monitoring inorganic, organic and total phosphorus in sediments.
Abstract: A simple, rapid and semi-automated method for the determination of inorganic, organic and total phosphorus in lake and river sediments is described. Total phosphorus is extracted from sediments with 1 N hydrochloric acid after ignition at a high temperature (550 °C) or by digestion with sulphuric acid-potassium persulphate at 135 °C in a sealed PTFE-lined Parr bomb. Organic phosphorus is determined by the difference in phosphorus content of the 1 N hydrochloric acid extract measured before and after ignition of the dry sediments at 550 °C. In all instances the orthophosphate is determined by using standard Technicon AutoAnalyzer II techniques. The interferences caused by silica and variable acid concentrations on the determination of phosphorus have been studied. Freedom from interferences under the chosen experimental conditions as well as the good results obtained for recovery and precision indicate that the methods are suitable for monitoring inorganic, organic and total phosphorus in sediments.
871 citations
TL;DR: In this article, a brief study was made of the extractability of a large number of metals from sediments, using different extraction techniques, including acid-extractable and cold extractable methods.
Abstract: A brief study was made of the extractability of a large number of metals from sediments, using different extraction techniques. Total, acid-extractable and cold-extractable metal extraction methods were compared in order to obtain the best technique applicable to environmental analysis. Extraction techniques for use with easily extractable metals were studied in detail, including their behaviour with respect to organic carbon content and type of lake or river sediment.
390 citations
TL;DR: Duplicate analytical results can be used to give rapid and realistic estimates of precision in analytical systems, but some common data-recording practices can lead to erroneous estimates of detection limit.
Abstract: Duplicate analytical results can be used to give rapid and realistic estimates of precision in analytical systems. In particular the effects of varying concentration of analyte on the variance of the measurement can be taken into account. When only small numbers of duplicate observations are available, the precision can be rapidly tested against an empirical standard level by use of a special control chart. Some common data-recording practices, however, can lead to erroneous estimates of detection limit, irrespective of the estimation procedure employed.
231 citations
TL;DR: In this paper, a fluorimetric method using the reagent Lumogallion has been investigated and found to have a detection limit of 0.05 µg l−1 of aluminium and a coefficient of variation of 5% at the 1.0 µg L−1 level and 2.7% at 22 µgL−1 levels.
Abstract: Dissolved aluminium occurs in natural waters down to concentrations of 1 µg l–1 or less. There are very few methods that are sufficiently sensitive to measure down to these levels. A fluorimetric method using the reagent Lumogallion has been investigated and found to have a detection limit of 0.05 µg l–1 of aluminium and a coefficient of variation of 5% at the 1.0 µg l–1 level and 2.7% at the 22 µg l–1 level. The only anionic interference likely to be important in most natural waters is that from fluoride, and this interference can be dealt with by using an incremental calibration procedure. For acidic waters iron is a potential interferent but has no significant effect at concentrations of less than 100 µg l–1. In water abnormally rich in dissolved organic material there may be competition for the dissolved aluminium between the natural organic ligands and the Lumogallion. This effect can be overcome by ultraviolet irradiation prior to analysis for aluminium. The analysis detects all forms of aluminium in filtered natural water samples except when the aluminium occurs in stable mineral structures, e.g., clay particles small enough to pass through the filter. Aluminium adsorbed on the surface of such particulate material appears to be determined.
229 citations
TL;DR: A dissolution technique has been developed for herbage and the method applied to the analysis of water and orchard leaves and maintenance of the pH between 4 and 5 permits the selective determination of arsenic(III) in mixtures of arsenic (III) with arsenic(V).
Abstract: In the atomic-absorption determination of arsenic by the hydride evolution method with sodium borohydride, maintenance of the pH between 4 and 5 permits the selective determination of arsenic(III) in mixtures of arsenic(III) with arsenic(V). Total arsenic can be determined separately by evolution from 5 M hydrochloric acid. A dissolution technique has been developed for herbage and the method applied to the analysis of water and orchard leaves.
146 citations
TL;DR: In this article, a simple single-beam spectrometer suitable for the study of optoacoustic spectra from small solid samples is described and the design of a suitable sample cell is reported.
Abstract: A simple single-beam spectrometer suitable for the study of optoacoustic spectra from small solid samples is described and the design of a suitable sample cell is reported. The performance characteristics of the spectrometer have been evaluated using different types of sample. A preliminary assessment of the predicted advantages of optoacoustic spectrometry over conventional techniques of ultraviolet-visible absorption and reflectance spectrometry for solid samples has been made.
105 citations
TL;DR: Optoacoustic spectrometers have been used in the analysis of a variety of sample types; several inorganic species, including rutile and anatase titanium(IV) oxide, organometallic and water-sensitive compounds, have been examined and optoACoustic spectra have been obtained from a series of haemoproteins of biological origin and from botanical samples as discussed by the authors.
Abstract: Some preliminary studies concerned with the application of optoacoustic spectrometry to chemical analysis are described and modifications made to improve the performance of the spectrometer that was discussed in Part I of this series are reported.This instrument has been used in the investigation of a variety of sample types; several inorganic species, including rutile and anatase titanium(IV) oxide, organometallic and water-sensitive compounds, have been examined and optoacoustic spectra have been obtained from a series of haemoproteins of biological origin and from botanical samples. Where comparisons are possible the spectra obtained by using optoacoustic spectrometry are similar to those obtained by use of conventional transmission or reflectance spectrometry. In general, however, optoacoustic spectrometry has the advantage of the requirement of only small (microlitre or microgram) amounts of sample. Spectra obtained from fresh leaf tissue indicate that optoacoustic spectrometry has a particular advantage over conventional techniques in that for heterogeneous samples of this type it is possible to generate separate spectra from different compounds by observing spectra in a phase-delayed mode; this effect can be used to advantage in the examination of surface layers without interference from substrate material.
75 citations
TL;DR: This work has shown that saturation of the aqueous phase with sodium chloride results in complete extraction of OTC into the organic phase, and this effect enables OTC to be determined in the presence of TC and CTC.
Abstract: A method for the fluorimetric determination of tetracyclines in biological materials based on solvent extraction of mixed tetracycline-calcium trichloroacetate ion pairs from aqueous solutions is described. The extraction of tetracycline (TC) and chlorotetracycline (CTC) is almost quantitative, whereas only very poor extraction occurs with oxytetracycline (OTC). However, saturation of the aqueous phase with sodium chloride results in complete extraction of OTC into the organic phase. This effect enables OTC to be determined in the presence of TC and CTC. Ethyl acetate was found to be the most suitable extractant. The fluorescence of the organic phase is measured after addition of magnesium ions and a base.The excitation maxima of all three tetracycline derivatives are at about 400 nm and emission maxima are at 500 nm. They differ only very slightly and cannot be used for differentiation between the derivatives. The following detection limits for CTC in biological materials were found: serum, 0.05 µg ml–1; muscle tissue, 0.125 µg g–1; kidney, 0.15 µg g–1; liver, 0.3 µg g–1; and milk powder with high fat content, 2 µg g–1. Recoveries were between 30 and 45%.
73 citations
TL;DR: In this paper, a high-voltage spark, operating at 50 Hz, is used for sampling and nebulising material from solid conducting samples for analysis by atomic-absorption, atomic-fluorescence or plasma emission spectrometry.
Abstract: A conventional high-voltage spark, operating at 50 Hz, is used for sampling and nebulising material from solid conducting samples. Gas, fed through the spark chamber, transports the metal particles into a flame or plasma for analysis by atomic-absorption, atomic-fluorescence or plasma emission spectrometry. Calibration graphs for the copper present in aluminium alloys and iron in brass are presented.
73 citations
TL;DR: In this paper, Monte Carlo simulation has been applied to test the robustness of a method for estimating precision as a function of concentration, and the effect of deviations from the basic assumptions underlying the method are shown to be generally fairly small.
Abstract: Monte Carlo simulation has been applied to test the robustness of a method for estimating precision as a function of concentration. The effect of deviations from the basic assumptions underlying the method are shown to be generally fairly small. The causes of such departures can be identified when they occur with actual laboratory results. Methods of recording laboratory observations can cause an over-optimistic bias of precision estimates in some circumstances.
73 citations
TL;DR: Barium ion-selective electrodes made from discs taken from a master membrane containing 0.40 g of a saturated solution of Antarox CO-880 were used as indicator electrodes for the potentiometric titration of SO42-with Ba2+ as mentioned in this paper.
Abstract: The barium ion-selective electrode sensor based on the neutral carrier complex of a nonylphenoxypoly(ethyleneoxy)ethanol containing 12 ethylene oxide units and 2 mol of tetraphenylborate ion per mole of Ba2+(12 EOU. Ba.2TPB) requires a more viscous solvent mediator than 4-nitroethylbenzene for long-life poly(vinyl chloride)(PVC) matrix-membrane barium ion-selective electrodes. Both 2-nitrophenyl octyl ether and di-2-nitrophenyl ether used in conjunction with the sensor in a PVC matrix membrane give functional barium ion-selective electrodes, but those with di-2-nitrophenyl ether mediator are far superior with lifetimes of about 30 d. Barium ion-selective electrodes with the sensor and mediator in liquid membranes can be made for a wide range of nitro-aromatic solvent mediators.Barium ion-selective electrodes made from discs taken from a master membrane containing 0.40 g of a saturated solution of Antarox CO-880. Ba.-2TPB in di-2-nitrophenyl ether can be used as indicator electrodes for the potentiometric titration of SO42– with Ba2+. A role for a potentiometric titration finish in the determination of sulphur in organic compounds by the oxygen-flask method is recommended.
TL;DR: An improved digestion procedure for the extraction of mercury from environmental material is reported, and with this procedure mercury is successfully recovered from organic matter and resistant inorganic forms such as mercury(II) sulphide.
Abstract: An improved digestion procedure for the extraction of mercury from environmental material is reported. The method involves the digestion of the sample at 60 °C with sulphuric acid-nitric acid (2 + 1), containing a trace amount of hydrochloric acid, and subsequent oxidation with permanganate and persulphate solutions. With this procedure mercury is successfully recovered from organic matter and resistant inorganic forms such as mercury(II) sulphide. Unlike digestion with aqua regia, this procedure is simple and safe, and is applicable to the digestion of a large number of samples simultaneously. The method can be adapted to the automated cold-vapour and flame atomic-absorption techniques and is therefore ideal for routine monitoring.
TL;DR: A method has been devised for the determination of N-nitrososarcosine, representative of the group of non-volatile nitrosamines of physiological origin, whereby the nitrosamine is denitrosated with hydrogen bromides to form the volatile nitrosyl bromide.
Abstract: A method has been devised for the determination of N-nitrososarcosine, representative of the group of non-volatile nitrosamines of physiological origin, whereby the nitrosamine is denitrosated with hydrogen bromide to form the volatile nitrosyl bromide. After dehalogenation in a heated converter, the nitrosamine can be determined as nitric oxide by using a chemiluminescence analyser, the response being linear up to at least 200 µg. The limit of detection is below 6 ng, and is therefore much lower than that for the determination of N-nitrososarcosine as inorganic nitrite in solution after denitrosation. A response is also obtained from inorganic nitrite but this can be differentiated from that of N-nitrososarcosine by the use of acetic acid alone, prior to denitrosation with hydrogen bromide in the same solvent.
TL;DR: It appears that the sensitivity specificity and broad applicability of radioimmunoassay will make it an increasingly attractive technique for determining drug levels in biological fluids.
Abstract: Literature on the radioimmunoassay of drugs is reviewed. The basis requirements advantages and disadvantages and anticipated trends of drug radiommunoassay are discussed. It appears that the sensitivity specificity and broad applicability of radioimmunoassay will make it an increasingly attractive technique for determining drug levels in biological fluids. In order to insure good results each antiserum must be assessed in regard to its cross-reactivity with the particular drug its stereoisomers and metabolites and exogenous and endogenous analogues. The labeled drug should be repeatedly assessed by both physicochemical and immunological methods. Physicochemical techniques such as mass spectrometry and gas-liquid chromatography can be helpful in reducing the chance of erroneous resuls. The results from radioimmunoassay of a hormone should also be compared with results obtained by bioassay.
TL;DR: The technique of gas-phase atomisation of the volatile hydrides in a heated silica tube and measurement of the resulting atomic-absorption signal has been extended to the determination of lead in air, water and vegetation.
Abstract: The technique of gas-phase atomisation of the volatile hydrides in a heated silica tube and measurement of the resulting atomic-absorption signal has been extended to the determination of lead in air, water and vegetation. The sample solutions, containing 0.7%V/V of nitric acid or 1.0%V/V of perchloric acid, are made to react with 12%V/V hydrogen peroxide solution followed by 4%m/V sodium borohydride solution by means of a peristaltic proportioning pump. The gaseous hydrides generated are swept by a stream of nitrogen into a heated silica tube and the absorbance of lead at 217 nm is recorded. The effects of interferences and their elimination are discussed. Results obtained on a few typical samples by the proposed method and an alternative method are presented.A sensitivity of 0.6 ng ml–1 and a detection limit of 0.1 ng ml–1 have been achieved. The relative standard deviation of the method is 2.5% at a lead concentration of 10 ng ml–1. Up to 50 samples can be analysed in 1 d.
TL;DR: Losses of chromium, iron, zinc and cadmium during ashing were studied using tissues that contained endogenously incorporated radioisotopes, finding no evidence for the formation of volatile compounds from the endogenous incorporated isotope.
Abstract: Losses of chromium, iron, zinc and cadmium during ashing were studied using tissues that contained endogenously incorporated radioisotopes. No losses on drying at 110 °C and no volatility losses were detected for any of the elements at temperatures below 600 °C. Chromium was lost from blood but not from liver samples heated at 700 °C. Losses as insoluble material on the crucible surfaces were more significant. Up to 42% of the isotope was retained on the dish after dissolution with acid, the amount depending on the ashing temperature, crucible material and surface condition. No evidence for the formation of volatile compounds from the endogenously incorporated isotope was found.
TL;DR: In this article, the authors describe the practical application of Truesdale and Smith's (1975) fundamental re-appraisal of the conditions that lead to the formation of α- and β-molybdosilicic acid in aqueous solutions.
Abstract: This paper describes the practical application of Truesdale and Smith's (1975) fundamental re-appraisal of the conditions that lead to the formation of α- and β-molybdosilicic acid in aqueous solutions. Two procedures, one using the α-acid and the other the β-acid, are proposed. Both procedures are designed so as to enable silicate-silicon concentrations of between 0 and 1·0 mg l–1 to be determined, although slight adjustments to the manifold of the Technicon AutoAnalyzer II system would make both suitable for other concentration ranges. The appropriate “molybdenum blues” derived from the yellow acids are used.Tests of the precision of both procedures were made at five concentration levels between 0 and 1·0 mg l–1 of silicate-silicon in distilled water. The maximum value of the coefficient of variation was 1·44 per cent. In other tests 27 samples of natural water from the upland area surrounding the sources of the rivers Wye and Severn were analysed by both methods. The results suggest that for these types of water the methods yield the same value for silicate concentration.
TL;DR: A gas-liquid chromatographic method involving electron-capture detection has been developed for the determination of an acrylamide monomer present in trace amounts in water and no interferences were observed from sea water or from 8.0% of ammonium ions present as ammonium bromide.
Abstract: A gas-liquid chromatographic method involving electron-capture detection has been developed for the determination of an acrylamide monomer present in trace amounts in water. The method is based on bromination of the double bond by means of an ionic reaction and the 2,3-dibromopropionamide produced is extracted twice with 10 ml of ethyl acetate after salting out with sodium sulphate. The 2,3-dibromopropionamide from the reaction mixture is then cleaned up by using a Florisil column.The calibration graph for the method is linear over the range 0–50 pg of acrylamide monomer and the limit of detection is 0.032 µg l–1 for an aqueous standard solution. The yields of the brominated compound are 85.2 ± 3.3 and 83.3 ± 0.9% at fortification levels of 1.0 and 5.0 µg l–1, respectively. Recoveries of acrylamide monomer from river water, sewage effluent and sea water spiked at a level of 0.20 µg per 50 ml are 99.4 ± 2.5, 101.3 ± 3.0 and 98.0 ± 3.2%, respectively. No interferences were observed from sea water or from 8.0% of ammonium ions present as ammonium bromide.
TL;DR: The direct determination of bismuth in urine by means of hydride generation has been investigated, and it is shown that there is severe suppression and poor recovery.
Abstract: Bismuth is determined in blood and urine by means of atomic-absorption spectrophotometry following generation of bismuth hydride from a wet-oxidised sample. Recoveries are shown to be satisfactory, and the detection limit using analytical-reagent grade reagents is less than 0.01 µg ml–1.The direct determination of bismuth in urine by means of hydride generation has been investigated, and it is shown that there is severe suppression and poor recovery.
TL;DR: In this paper, it was shown that when the sample contains a preponderance of acidic oxides (e.g., silica), lithium metaborate has considerable advantages.
Abstract: From experience of the use of both lithium metaborate and tetraborate as fluxes for a wide variety of minerals and refractories, it is postulated that when the sample contains a preponderance of acidic oxides (e.g., silica), lithium metaborate has considerable advantages. The melts from metaborate are much more fluid and decomposition can be carried out by heating over gas burners. For samples that contain high contents of basic oxides (e.g., carbonate rocks), the more acidic tetraborate is recommended. A 1 + 4 mixture of metaborate and tetraborate forms a universal flux for samples containing silica and/or alumina as major contents. The most suitable flux can be predicted from the acidity or basicity of the sample.
TL;DR: Trace amounts of selenium(VI) and total seenium in milk, milk products and albumin were determined by this method with a practical detection limit of 0.005 µg.
Abstract: Selenium(IV) reacts with 1,2-diamino-4-nitrobenzene to form 5-nitropiazselenol, which is detected by means of a gas chromatograph equipped with an electron-capture detector. Trace amounts of selenium(VI) and total selenium in milk, milk products and albumin were determined by this method with a practical detection limit of 0.005 µg. The amount of selenium(VI) found in milk was about 60% of the total selenium content.
TL;DR: In this paper, the determination of bismuth at the 0-1 p.p.m. level in nickel-base alloys after dissolution of the alloy followed by generation of Bismuth hydride and its subsequent measurement by atomic-absorption spectrophotometry is discussed.
Abstract: A requirement has arisen in the aero-engine industry for a method that is capable of determining trace amounts of bismuth in complex nickel-base alloys. This paper deals with the determination of bismuth at the 0–1 p.p.m. level in nickel-base alloys after dissolution of the alloy followed by generation of bismuth hydride and its subsequent measurement by atomic-absorption spectrophotometry. Interference effects, due to the complex matrix, have been overcome and a procedure has been developed that is rapid and sensitive at these very low levels. The method is applicable to a wide range of nickel-base alloys commonly used in the aero-engine industry.
TL;DR: In this paper, the citrate complex method was applied to ashes of commercial tea, high in aluminium and iron, gave recoveries of fluoride ion of greater than 90% in the presence of aluminium, iron, magnesium or silicate.
Abstract: Plant ashes may contain sufficient aluminium and/or iron to interfere seriously in the determination of fluoride ions when using the fluoride ion selective electrode. In the presence of these metals the known additions method gave erroneous results, as did that involving the attempted formation of complexes with ethylenediaminetetraacetic acid, disodium salt, or 1,2-cyclohexylenedinitrilotetraacetic acid. Good recoveries of fluoride ion were obtained in the presence of aluminium, iron, magnesium or silicate, using sodium citrate as the complexing agent. The application of the citrate complex method to ashes of commercial tea, high in aluminium and iron, gave recoveries of fluoride ion of greater than 90%.
TL;DR: The proposed method is about eight times more sensitive than that based on the ammonium tetrathioisocyanatocobaltate(II) reagent and it gives results for the absolute concentration with an accuracy ranging from –6 to +8 per cent.
Abstract: A method is proposed for the determination of polyoxyethylene alkylphenyl ethers, RO(CH2CH2O)nH (where R is an alkylphenyl group), at the 1–0.1 mg l–1 level in waters. The method is based on the spectrophotometric determination of the complexes of the polyethers with the sodium cation after extraction as picrates into 1,2-dichloroethane. The number-average degree of polymerisation (text-decoration:overlinen) is evaluated by thin-layer chromatography or by gas chromatography.The method was tested on commercial compounds that have R =p-tert-nonylphenyl (3.3 ⩽text-decoration:overlinen⩽ 21.5). For typical surfactants (6.5 ⩽text-decoration:overlinen⩽ 21.5) the proposed method is about eight times more sensitive than that based on the ammonium tetrathioisocyanatocobaltate(II) reagent and it gives results for the absolute concentration with an accuracy ranging from –6 to +8 per cent. in the indicated interval of text-decoration:overlinen. The precision was evaluated from the analysis of waste waters. A few interferences are discussed.
TL;DR: A comparison of procedures that involve the use of either carbon rod or carbon furnace atomisation in order to determine, by atomic-absorption spectrometry, the level of gold in whole blood, plasma and serum from patients undergoing gold treatment for rheumatoid arthritis is described.
Abstract: A comparison of procedures that involve the use of either carbon rod or carbon furnace atomisation in order to determine, by atomic-absorption spectrometry, the level of gold in whole blood, plasma and serum from patients undergoing gold treatment for rheumatoid arthritis is described. A procedure using carbon furnace atomisation is preferred because of its simplicity and sensitivity. The detection limits for gold, obtained by using the preferred procedure, in serum, plasma and whole blood are 0.002, 0.002 and 0.004 5 µg ml–1, respectively. The relative standard deviations are 1.9% for 0.063 µg ml–1 in serum, 2% for 0.061 µg ml–1 in plasma and 7.3% for 0.030 µg ml–1 in whole blood. The method is used to confirm that most gold is carried in the serum fraction of blood, to determine the gold level in white cells and to demonstrate that the gold level in the ultra-filtrate is low.
TL;DR: A simple procedure involving a slurry has been used for the determination of trace elements in titanium(IV) oxide pigments by means of atomic-absorption spectrometry as discussed by the authors, and both electrothermal and flame atomisation techniques have been employed.
Abstract: A simple procedure involving a slurry has been used for the determination of trace elements in titanium(IV) oxide pigments by means of atomic-absorption spectrometry. Both electrothermal and flame atomisation techniques have been employed. The method has been used to determine copper, iron, manganese and lead by dispersing the pigments in water that contained 0.005%m/V of sodium hexametaphosphate. The limits for determination are as low as 0.1 µg g–1 using electrothermal atomisation and 2 µg g–1 using flame atomisation and a discrete sampling procedure.The advantages of this technique are its simplicity, speed of analysis and reduction of blank levels.
TL;DR: A differential pulse polarographic method for the determination of residues of glyphosate herbicide in natural waters down to 35 µg l–1 is described and a polarographically active glyphosate derivative is obtained by nitrosation performed directly in a fraction of the eluate from the column.
Abstract: A differential pulse polarographic method for the determination of residues of glyphosate herbicide in natural waters down to 35 µg l–1 is described. The material is concentrated by chromatography on an anion-exchange column, which at the same time serves as the only clean-up step required. A polarographically active glyphosate derivative is obtained by nitrosation performed directly in a fraction of the eluate from the column. The precision in terms of relative standard deviation varies from 22.8% at the detection limit to 2.3% at 210 µg l–1. The total analysis time for one sample is 3–4 h.