Showing papers on "Fluorescence spectrometry published in 1977"

High-performance liquid-chromatographic analysis for tryptophan in serum.

Abstract: Concentrations of total tryptophan were determined rapidly and sensitively in 50 microliter of serum by a reversed-phase partition version of high-performance liquid chromatography. For determination of total tryptophan, sample preparation requires only precipitation of the serum protein with trichloroacetic acid and removing excess trichloroacetic acid with a 1,1,2-trichlorotrifluoroethane(Freon)/tri-N-octylamine solution. Tryptophan in serum samples was detected by ultraviolet and fluorescence spectrometry. No interferences from the naturally occurring constituents of serum were observed. Elution time for tryptophan is 15 min, the limit of detection is 1 pmol.

Determination of ruthenium and chromium by X-ray fluorescence spectrometry and the use of inert ruthenium (II) phenanthroline as a solid phase marker in sheep digestion studies

Abstract: The quantitative estimation of ruthenium and chromium in faeces and digesta from sheep by X-ray fluorescence spectrometry is described. Estimates of calibration parameters, established by regression analysis, were applicable to a range of matrices. Lower limits of detection of 2·4 mg Ru/kg (solid), 1·8 mg Ru/1 (liquid), 1·6 mg Cr/kg (solid) and 1·1 mg Cr/1 (liquid) and precisions, expressed as coefficients of variation, of 5·4% at 17·7 mg Ru/kg (solid), 5·1% at 182·7 mg Cr/kg (solid) and 1·1% at 152 mg Cr/1 (liquid) were acceptable for the routine analysis of Ru and Cr. The use of inert ruthenium phenanthroline (Ru-P) and inert chromium ethylenediamine tetra-acetic acid (Cr-EDTA) as solid:liquid dual phase markers in digestive physiological studies was evaluated. The specificity of Ru-P for the particulate phase of digesta, established by both in vitro and in vivo experiments, was found to be 92–98%, and in vivo recovery of intraruminally administered Ru-P in faeces was 97–101%. In vitro incubation of rumen liquor showed that concentrations of Ru-P up to 10 −4 M had little effect on volatile fatty acid production rates but at 10 −3 M there was virtually complete inhibition of acetate and propionate production. Advantages of using inert Ru-P as a solid phase marker are discussed.

Analysis of plant material by X‐ray fluorescence spectrometry

Abstract: To get a better understanding of chemical changes accompanying reproduction, maturation and senescence of plants, plant samples collected in various marshes were analysed by X-ray fluorescence spectrometry for Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe with sufficiently accurate results. The preparation of pellets from unground, coarse and finely ground plant material was investigated and no significant difference was found in X-ray count rates. A computer program was developed for routine analyses of plant material using NBS standard Orchard Leaves.

The non-destructive analysis of single layered household paints using energy dispersive x-ray fluorescence spectrometry.

Abstract: An evaluation of energy dispersive X-ray fluorescence spectrometry for the discrimination of single layered household paint flakes of similar colour is reported. Thirty paint samples, ten from each of the three colour groups red, green and white, were analysed under standard conditions. The reproducibility of the X-ray fluorescence spectra, for 2mm × 2mm flakes removed from different areas of a painted slide, has been investigated. Using 2mm × 2mm flakes discrimination of all the paints within the red and green colour groups was achieved. The white paint flakes were discriminated into nine groups. A combination of several other techniques could not achieve discrimination of all the samples. The spectra for all the paints examined are shown and the limitations of the method are discussed.

Comparison of Two Background Correction Procedures for X-Ray Fluorescence Trace element Analysis of Some Standard Samples

Abstract: Ten geochemical reference samples were analysed for Rb, Sr and Cr by X-ray fluorescence spectrometry. The results obtained by two different background correction procedures are compared. For Sr both the correction procedures yield almost similar results in carbonate matrix; however, for Rb and Sr in silicate samples some significant differences are often noticed.

Applications de la spectrométrie de rayons x à l'analyse de matériaux macromoléculaires. II. Etude de polyéthylènes chlorés en surface

Abstract: Les concentrations superficielles en chlore (jusqu'a 500 μg.cm-2 environ) de films de polyethylene chlores en surface, sont determinees par spectrometrie de fluorescence. X.A l'aide d'aide d'etalons appropries, on montre que les echantillons consideres ne peuvent etre assimiles a des films minces que dans la mesure ou la radiationexcitrice equivalente du spectre X primaire est sufisamment energetique. Ces travaux permettent en outre, d'estimer l'epaisseur de chloration (jusqu'a 4 μm environ) en fonction de la duree du processus d'halogenation. The chlorine concentrations in the range up to about 500 μg.cm-2 of surface chlorinated polyethylene films were determined by X-ray fluorescence spectrometry. By using appropriate standards, it is shown that the investigated samples can be regarded as thin films only when the energy of the «equivalent» primary X-radiation is high enough. Results allow to estimate (in the range up to about 4 μm) the chlorinated film thicknesses versus duration of the halogenation processes.

Quantitative Determination of Benzo[a]pyrene in Foodstuffs Using Benzo[a]pyrene[G-3H]

Abstract: A method for quantitative determination of nano gram level of benzo[a]pyrene (BP) in foodstuffs using tritiated BP (3H-BP) was described. Extracts from foodstuffs, having been added a certain amount of 3H-BP, were fractionated by column chromatography on Florisil, and thinlayer chromatography on acetylated cellulose. Concentration and radio activity of BP in the final fraction were determined by fluorescence spectrometry and liquid scintillation. Recovery ratio of each experiment was obtained by comparing the radio activities of added 3H-BP and separated BP. Concentration of BP in the sample analyzed was calculated from the amount of isolated BP and the recovery ratio in each experiment. A quantitative limit of BP by this method was 0.2 ppb when 50 g of sample was used.By this method, contents of BP in each sample of Tenpura oil, salad oil, flour, and polished rice were determined as 0.6, 0.2, 0.1, and <0.1 ppb on average, respectively.

Degradation Studies of a Trimethylolpropane Triheptanoate Lubricant Basestock

Abstract: : Experiments are described to study the thermal and oxidative degradation of a typical neopentyl-type polyol ester lubricant basestock-- trimethylolpropane triheptanoate. Utilizing a rotating cylinder device for the formation of a thin fluid film (0.004 in.), the parameters of film temperature, atmosphere moisture, and atmosphere type (inert or oxidative) were investigated with the uninhibited basestock. Program objectives included elucidation of the chemical processes involved in fluid deterioration, particularly as related to the formation of deposits. Reactants and products were measured by various analytical techniques, principally gas chromatography, gas chromatography/mass spectrometry, and X-ray fluorescence spectrometry. A literature search pertinent to the chemistry of synthetic, ester-base lubricants and methods of chemical analysis of such lubricants is also presented.