Showing papers on "Fluorescence spectrometry published in 1973"

The chemical composition of kainsaz and efremovka

Abstract: The type III carbonaceous chondrites Kainsaz and Efremovka have been analysed for eighteen major, minor and trace elements by X-ray fluorescence spectrometry. A comparison of the data on Kainsaz with four other Ornans sub-type carbonaceous chondrites reveals a remarkable degree of constancy of composition. Efremovka, together with Leoville and Coolidge, may be distinguished from the other Vigarano sub-type carbonaceous chondrites by their lower Na and K contents, variable Na/K ratios and relatively low Ca/Al ratios. Some observations are made on the ratio Na/K in various types of stony meteorite; the magnitude of the ratio in the basaltic achondrites appears to be more similar to that in the carbonaceous chondrites than in the ordinary chondrites.

Pesticide stability in cold-stored plant parts, soils, and dairy products, and in cold-stored extractives solutions.

Abstract: The field of pesticide1 residue analyses has seen tremendous advances in recent years. The application of new as well as elsewhere-established analytical techniques and instrumentation to this field of research has been the main contributing factor to these advances. For example, the adaptation in 1961 of gas-liquid chromatography (glc) to the analysis of pesticide residues and their alteration products has given the trained residue chemist a superlative tool for his work, when properly used and interpreted. Other more definitive residue-analytical and confirmatory techniques have exploited infrared, ultraviolet, and fluorescence spectrometry, mass spectroscopy, micropolarography, atomic absorption spectroscopy, carbon skeletonization glc, etc. The importance of colorimetry, thin-layer chromatography (TLC), cholinesterase (ChE) assay, and other separating and determinative techniques should not be overlooked as valuable components of definitive apid credible pesticide residue programs.

Polyaromatic hydrocarbons in high-boiling petroleum distillates. Isolation by gel permeation chromatography and identification by fluorescence spectrometry

Abstract: The identification of seven polyaromatic ring systems in petroleum is reported. The ring systems are 1.12,2.3-dibenzoperylene; 1,12-o-phenyleneperylene, pyreno(1.3:10'.2')pyrene; 2.3,10.11-dibenzoperylene; 1,2,4,5-dibenzopyrene, benzo(e)pyrene, and benzo(g)chrysene. These polyaromatic hydrocarbons were isolated by a separation scheme involving ion exchange chromatography, gel permeation chromatography, and thin-layer chromatography and were identified by fluorescence spectroscopy. Gel permeation chromatogaphy separated pericondensed aromatic ring systems from catacondensed ring systems and the other components of an acid concentrate.

A chemical concentration method for the determination of niobium, zirconium and tantalum in carbon steel by X-ray fluorescence spectrometry

Abstract: A chemical concentration technique is described for the simultaneous determination of small added amounts of zirconium and niobium (less than 0·05 per cent.) and residual amounts of tantalum (less than 0·01 per cent.) in carbon steel by X-ray fluorescence spectrometry. Separation from iron and other constituents is effected by precipitation with phenylarsonic acid; the precipitate is then collected on an organic membrane and X-ray measurement made either directly on the precipitate or after pelleting with poly(vinyl alcohol). The results obtained for niobium and zirconium in the test samples compare favourably with published values by other techniques.

Multiwavelength laser induced fluorescence of algae in-vivo - A new remote sensing technique

Abstract: In order to accurately determine the quantity of chlorophyll a in living algae by fluorescence spectrometry, either remotely or in the laboratory, the fluorescence excitation cross section must be known. Laboratory fluorescence studies of a number of different algae species representative of the various color groups were performed. These measurements indicate distinct maximum spectral excitation regions which differ from one color group to another. Within each color group, however, the fluorescent properties were nearly identical, regardless of species. These two key features - namely, the similarity of fluorescent properties within a color group, and the distinct spectral differences between color groups - make possible the simultaneous determination of chlorophyll a content of an unknown mixture of phytoplankton and the distribution of chlorophyll a among the various color groups.

The youndegin meteorite shower

Abstract: A detailed examination of the geographical location, microstructure and chemical composition of the Mt. Stirling, Mooranoppin, Quairading and Youndegin siderites has led to the conclusion that they are all members of one meteorite shower. The cobalt, nickel, gallium and germanium contents of 10 of these meteorites have been determined by X-ray fluorescence spectrometry, and this enables them to be classified as members of chemical group 1.

Mixed-Bed Ion-Exchange Papers

Abstract: Retention of some cations and anions on ion-exchange resin-loaded disks has been reported to be less than quantitative. A mixed-bed resin-loaded paper was made in which mixed cation-exchange and anion-exchange resins were incorporated into the paper to take advantage of the ‘crossed equilibria’ effect and improve ion retention. The use of mixed-bed paper disks in analysis for cesium by X-ray fluorescence spectrometry is described.