Showing papers in "Analyst in 1977"
TL;DR: A specific method for the spectrophotometric determination of total steroidal sapogenin, based on colour reactions with anisaldehyde, sulphuric acid and ethyl acetate and applicable to microgram amounts, is described.
Abstract: A specific method for the spectrophotometric determination of total steroidal sapogenin, based on colour reactions with anisaldehyde, sulphuric acid and ethyl acetate and applicable to microgram amounts, is described.It has been shown that this determination can be carried out directly on a saponin solution and that there is virtually no interference from sugars, sterols, fatty acids and vegetable oil. The sapogenins have the same colorimetric properties whether they are in the free state, bound with sugars, esterified with acetic acid or mono- or polyhydroxylated. The method described is accurate (relative error 1.4%), rapid, easily automated and gives a chromophore with the same absorption spectrum with only one peak at 430 nm for all of the sapogenins tested: diosgenin, tigogenin, hecogenin, smilagenin, yonogenin, tokorogenin, etc. The molar absorption coefficient is approximately 49 000.
201 citations
TL;DR: Theoretical expressions have been developed to relate the optical and thermal properties of such samples to the amplitude and phase of the signals observed in optoacoustic spectrometry when using dispersive and non-dispersive techniques as discussed by the authors.
Abstract: Optoacoustic spectrometry can be employed to obtain data concerning the spectral absorption characteristics and thermal diffusivity of small solid samples. Theoretical expressions have been developed to relate the optical and thermal properties of such samples to the amplitude and phase of the signals observed in optoacoustic spectrometry when using dispersive and non-dispersive techniques. The validity of these expressions has been examined by using transparent and opaque materials with widely differing thermal diffusivities.
155 citations
TL;DR: In this article, the turbidimetric determination of sulphate as barium sulphate has been adapted to the continuous flow injection procedure of Růžicka and co-workers.
Abstract: The turbidimetric determination of sulphate as barium sulphate has been adapted to the continuous flow injection procedure of Růžicka and co-workers. The effects of reagent composition, reagent flow-rates and length of mixing coils have been investigated. Optimum conditions were established for the determination of sulphate in natural waters and in plant digests. The results agree satisfactorily with those obtained by a standard turbidimetric method and analyses can be carried out at a rate of up to 180 samples per hour.
132 citations
TL;DR: In this paper, a simple apparatus was described that permits heat flow characteristics of a sample to be determined, and its application to the determination of the thermal diffusivity or thickness of polymer films on a copper substrate was reported.
Abstract: A simple apparatus is described that permits heat-flow characteristics of a sample to be determined, and its application to the determination of the thermal diffusivity or thickness of polymer films on a copper substrate is reported. The apparatus utilises the optoacoustic effect in which periodically interrupted radiation is absorbed by a solid sample to give rise to a similar periodic variation of the pressure of the air in contact with the sample surface in a closed cell. The amplitude and phase of the observed optoacoustic signal depend on the thermal diffusivity and thickness of the material irradiated.
99 citations
TL;DR: A simple, reliable and sensitive method for the automated determination of nitrate and its use for analysing soil extracts, waste waters, fertiliser solutions and air samples and a new approach to identifying and correcting for the presence of interfering species in potentiometric measurements is discussed.
Abstract: Based on the flow injection principle and employing a nitrate electrode situated in a flow-through cell, a simple, reliable and sensitive method for the automated determination of nitrate and its use for analysing soil extracts, waste waters, fertiliser solutions and air samples are described. At a sampling rate of 90 samples per hour a standard deviation of only 1–2% is typical. A new approach to identifying and correcting for the presence of interfering species in potentiometric measurements is discussed.
74 citations
61 citations
TL;DR: In this article, the optimisation of conditions is described for the quantitative determination of glucose, fructose, sucrose and lactose by high-performance liquid chromatography using a column of aminopropylsilane bonded to microparticulate silica.
Abstract: The optimisation of conditions is described for the quantitative determination of glucose, fructose, sucrose and lactose by high-performance liquid chromatography using a column of aminopropylsilane bonded to microparticulate silica. Analytical results for these sugars in boiled sweets, toffee and redcurrant jelly are compared with those obtained for the same components by an enzymatic procedure.
60 citations
TL;DR: Possible losses of trace elements during dehydration of marine zoological material with a high water content were studied by means of radioactive tracers, using the oyster Crassostrea gigas as an example, and serious losses of selenium, cadmium and lead were observed.
Abstract: Possible losses of trace elements during dehydration of marine zoological material with a high water content were studied by means of radioactive tracers, using the oyster Crassostrea gigas as an example. It is probable that no losses occurred with chromium, iron, manganese, cobalt and zinc, but serious losses of selenium, cadmium and lead were observed, both during freeze drying and oven drying at low temperatures. The analytical applicability of dehydration techniques in general thus requires re-assessment.
59 citations
TL;DR: In this paper, the results obtained with the flow injection methods and those attained by the manufacturer of the fertilisers with conventional techniques showed that flow injection analysis is potentially suitable for the routine analysis of these and similar substrates.
Abstract: Based on the flow injection technique and routinely using sample injections of 30 µl, and as low as 5 µl, reliable and sensitive methods for the determination of nitrate, potassium, phosphate and ammonia in fertilisers are described in which potentiometric and spectrophotometric detection is used. At sampling rates of 85–120 samples per hour high reproducibility of measurement and low reagent consumptions were achieved. The good agreement between the results obtained with the flow injection methods and those attained by the manufacturer of the fertilisers with conventional techniques shows that flow injection analysis is potentially suitable for the routine analysis of these and similar substrates.
52 citations
TL;DR: A method is described for the routine determination of selenium in blood and plant samples at concentrations in the range 0.01–0.50 µg g–1 and the efficiency of hydride generation was 95%.
Abstract: A method is described for the routine determination of selenium in blood and plant samples at concentrations in the range 0.01–0.50 µg g–1. Samples of mass 1 g are digested with nitric and perchloric acids and then selenium hydride is generated from diluted digests by the controlled introduction of a solution of sodium borohydride. The selenium is subsequently atomised in a nitrogen-hydrogen-entrained air flame. Digests can be analysed at a rate of four per minute. For a pasture sample, which contained a 0.038 µg g–1 concentration of selenium, and a blood sample, which contained 0.029 µg g–1 of selenium, relative standard deviations of 7.9 and 4.3%, respectively, were obtained. The mean recovery of added selenium was 100.5%, with a relative standard deviation of 4.7%. The efficiency of hydride generation was 95%.
TL;DR: A method involving the use of a reagent suitable for the rapid spectrophotometric determination of nitrites in water is described, featuring good selectivity and reproducibility, high stability of the coloured reaction product and simplicity.
Abstract: A method involving the use of a reagent suitable for the rapid spectrophotometric determination of nitrites in water is described. Nitrites react with resorcinol in an acidic medium and the nitroso product forms a pale yellow chelate with the zirconyl ion. The absorbance of the chelate is measured at 347 nm and the calculated molar absorptivity is 2.67 × 104 l mol–1 cm–1. The method is suitable for the determination of the nitrite ion in a 1.0-cm cell in the range from a few parts per hundred million to about 1 p.p.m. The relative standard deviation of the method is 1.5% at a concentration of 1 p.p.m. Some of the problematic interferents found in most of the analytical procedures for the determination of nitrites are tolerated in the present method. Features of the method include good selectivity and reproducibility, high stability of the coloured reaction product and simplicity.
TL;DR: In this paper, the determination of fluorine in silicate materials with a fluoride ion-selective electrode following fusion with lithium metaborate is described, and the results obtained compare well with accepted values for standard rock and mineral samples.
Abstract: The determination of fluorine in silicate materials with a fluoride ion-selective electrode following fusion with lithium metaborate is described. The method is rapid, and the values obtained compare well with accepted values for standard rock and mineral samples. Samples containing up to 2.7% of fluorine have been analysed by this method.
TL;DR: In this paper, the design, construction and performance characteristics of a double-beam optoacoustic spectrometer suitable for recording corrected spectra of small solid and liquid samples in the wavelength range 0.25-2.5 µm are described.
Abstract: The design, construction and performance characteristics of a double-beam optoacoustic spectrometer suitable for recording corrected spectra of small solid and liquid samples in the wavelength range 0.25–2.5 µm are described. Typical spectra obtained for rare earth oxides, titanium(IV) oxides, catalase, blood, cystine and kaolinite are presented in order to illustrate the performance of the instrument. The application of the spectrometer to record conventional solution transmittance spectra is also reported.
TL;DR: In this paper, an electromagnet was placed around a specially designed graphite furnace atomiser and the Zeeman effect generated in the atomised sample was used to correct for background absorption generated by the matrix.
Abstract: An electromagnet was placed around a specially designed graphite furnace atomiser and the Zeeman effect generated in the atomised sample was used to correct for background absorption generated by the matrix. The optical polarisation properties inherent in the Zeeman effect were utilised to generate two signals, one corresponding to the absorption of the atomic line plus background and the other to the background alone. A simple theoretical treatment was developed that related the observed atomic absorbance to a parameter dependent on magnetic flux density. This parameter, designated R in this work, is a function of the atomic line profile and the Zeeman splitting pattern of the line. The purpose-built apparatus incorporated facilities for simultaneous background correction by both the Zeeman and conventional deuterium-arc techniques.Measurements were made of the dependence of R on magnetic flux density for silver, gold, cadmium, chromium, mercury, potassium, magnesium, manganese, sodium, nickel and lead in the range 2–9 kG. A reduction in the analytical sensitivity of up to 35% arising from the Zeeman correction procedure was found in some instances. Calibration graphs for lead and nickel were linear with concentration change over two orders of magnitude but were found to invert at high concentrations (about 300 µg ml–1). Using the Zeeman correction system, a background absorbance of 2.0 was compensated to better than 0.005, while that achieved by a well adjusted deuterium arc system was approximately 0.02.
TL;DR: In this article, a simple and rapid method was described for the determination of cadmium and zinc in sea water, using atomic-absorption spectrometry with carbon furnace atomisation.
Abstract: A simple and rapid method is described for the determination of cadmium and zinc in sea water, using atomic-absorption spectrometry with carbon furnace atomisation. Samples, diluted 1 + 1 with de-ionised water, are injected into the carbon furnace and atomised in an HGA-72 furnace atomiser under gas-stop conditions. A low atomisation temperature of 1492 °C is used to separate the atomic-absorption signals from background absorption. Detection limits (2σ) of 0.04 µg l–1 for cadmium and 1.7 µg l–1 for zinc are reported. These limits appear to be adequate for all but the cleanest sea water samples. The use of standard addition is essential because of the interference from magnesium chloride and also when samples of varying salinity have to be analysed.
TL;DR: In this paper, it was shown that titanium(III) salts interfere with the method and must be removed if present in large amounts, which is a serious problem when large amounts of titanium are present.
Abstract: Nitrate can be rapidly reduced to ammonia by the action of titanium(III) sulphate, even at room temperature. Subsequent displacement of the ammonia by a current of air enables the gas-phase molecular absorbance of the ammonia to be measured and thus provides a sensitive and selective method for the determination of nitrate. Ions which affect the reduction of nitrate by titanium(III) salts interfere with the method and must be removed if present in large amounts.
TL;DR: A method for the determination of platinum, palladium, gold and iridium in geological materials following activation with thermal neutrons is described in this article, where radionuclides formed from the elements are separated by a scheme based largely on liquid-liquid extractions.
Abstract: A method for the determination of platinum, palladium, gold and iridium in geological materials following activation with thermal neutrons is described. Radionuclides formed from the elements are separated by a scheme based largely on liquid-liquid extractions. The procedure has been applied to the analysis of US Geological Survey standard rocks and to studies of the distribution of the noble metals in lateritic nickel ores.
TL;DR: In this paper, a method for the dissolution and determination of major and minor constituents in a wide range of compositions of siliceous materials is described, where boric acid is added after dissolution to complex excess of hydrofluoric acid and dissolve precipitated fluorides.
Abstract: The method described can be used for the dissolution and determination of major and minor constituents in a wide range of compositions of siliceous materials. A pressure dissolution vessel is used for fast and complete acid attack. The principle solvent is hydrofluoric acid, but boric acid is added after dissolution to complex excess of hydrofluoric acid and dissolve precipitated fluorides. A second heating step is shown greatly to improve the efficiency of this process.Most inter-element interferences are removed in the presence of the fluoroboric acid so formed when the dinitrogen oxide-acetylene flame is used. Neither releasing agents such as lanthanum nor detailed matching of standards to sample compositions are therefore necessary. Both macro- and micro-scale versions of the method are given, the latter having proved satisfactory for samples as small as 10 mg, such as those commonly encountered in archaeological work.
TL;DR: A method for determining residues of biphenyl, benomyl, carbendazim, 2-phenylphenol and thiabendazole, and the fungicides are determined by high-performance liquid chromatography using an ultraviolet spectrophotometric detector.
Abstract: A method for determining residues of biphenyl, benomyl, carbendazim, 2-phenylphenol and thiabendazole is presented. Samples are extracted by refluxing with dilute hydrochloric acid, the biphenyl and 2-phenylphenol being steam distilled and collected for determination separately. Benomyl is converted into carbendazim and both carbendazim and thiabendazole are separated from interfering co-extractives by partitioning with chloroform under acidic and basic conditions. Thiophanate-methyl can also be determined after conversion into carbendazim but the conversion is not quantitative. The fungicides are determined by high-performance liquid chromatography using an ultraviolet spectrophotometric detector.
TL;DR: In this paper, a polymer containing hydroxyl groups (copolymer VAGH) is incorporated into PVC matrices containing Orion 92-20-02 calcium liquid ion exchanger.
Abstract: Limited amounts of a polymer containing hydroxyl groups (copolymer VAGH) can be incorporated into PVC matrices containing Orion 92–20–02 calcium liquid ion exchanger. Such hydroxyl groups also provide suitable sites for grafting alkyl hydrogen phosphate calcium-ion sensors. Calcium ion-selective electrodes can also be fabricated from membranes containing the grafted sensors. These are of fast and steady response but there are no other noticeable advantages.Because of the nature of pH interference of calcium ion-selective electrodes based on alkyl phosphate sensors, improved electrode calibration can be obtained by calcium-ion standards in tris buffer at pH approximately 7.5.
TL;DR: In this article, a thin metal sulphide layer was treated by heating under a partial pressure of sulphur and the observed standard potential was used as a good criterion for judging electrode performance.
Abstract: Ion-selective electrodes for divalent metal ions (Cu2+, Pb2+, Cd2+, Hg2+) have been prepared by covering ionic conductors such as Ag2S, Ag3SBr or Ag3SI with a thin metal sulphide layer. The metal sulphide layer was treated by heating under a partial pressure of sulphur. The observed standard potential is a good criterion for judging electrode performance.
TL;DR: In this article, a method for the rapid and accurate spectrometric determination of the alloying and minor elements in copper-base alloys using a Grimm glow-discharge source was presented.
Abstract: A method is presented for the rapid and accurate spectrometric determination of the alloying and minor elements in copper-base alloys using a Grimm glow-discharge source. The remarkable lack of inter-element effects in this source enables a wide range of element concentrations to be measured with the use of a small number of standards. The accuracies for the major elements, including copper, are generally better than 0.2% relative.
TL;DR: A rapid and sensitive procedure is described for the determination of trace amounts of eight substituted phenylurea herbicides using a mixture of methanol, water and ammonia as mobile phase.
Abstract: A rapid and sensitive procedure is described for the determination of trace amounts of eight substituted phenylurea herbicides. High-performance liquid chromatography is used, with an ultraviolet spectrophotometric detector. The herbicides are extracted from grain and soil samples with methanol and from water samples with dichloromethane. They are chromatographed on microparticulate silica bonded with octadecyltrichlorosilane using a mixture of methanol, water and ammonia as mobile phase.
TL;DR: In this paper, molecular-emission spectra from CN and C2 radicals and from molecules formed during the atomisation of solutions of calcium, strontium and magnesium in carbon furnace atomisers are described.
Abstract: Molecular-emission spectra from CN and C2 radicals and from molecules formed during the atomisation of solutions of calcium, strontium and magnesium in carbon furnace atomisers are described. Spectra from metallic species are compared with analogous spectra observed by other workers in flames and arcs and are shown to be more closely related to the spectra of the oxide rather than hydroxide species of these elements.
TL;DR: In this article, it was shown that with careful optical design and alignment, the continuous background emission signal from a carbon furnace can be reduced to a minimum, when no radiation from the furnace wall enters the monochromator directly.
Abstract: Investigations have shown that with careful optical design and alignment the continuous background emission signal from a carbon furnace can be reduced to a minimum. When no radiation from the furnace wall enters the monochromator directly, the background signal is a result of Rayleigh scattering of furnace-wall radiation by atoms or molecules in the vapour phase of the furnace. Methods for further reducing the continuous background signal, including optical and furnace design, are discussed.
TL;DR: Simple and rapid procedures are described for the determination of gold in protein fractions of blood serum from patients undergoing chrysotherapy to confirm the accuracy of each procedure, with particular respect to possible re-distribution or loss of gold during the separation process itself.
Abstract: Simple and rapid procedures are described for the determination of gold in protein fractions of blood serum from patients undergoing chrysotherapy. Separation of proteins is achieved by electrophoresis, gel chromatography and, for albumin only, precipitation. Gold concentrations in the protein fractions are determined by carbon furnace atomic-absorption spectrometry using either direct insertion of sections of electrophoretic strips or the solutions resulting from the other separation procedures. Results from the different separation processes are used to obtain a more detailed analysis and to confirm the accuracy of each procedure, with particular respect to possible re-distribution or loss of gold during the separation process itself.