نتایج جستجو برای: chromium sampling method
تعداد نتایج: 1795033 فیلتر نتایج به سال:
National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Stro...
a new simple arid rapid catalytic kinetic method for determination of trace amounts of chromium (110 isdescribed. the method is based on the catalytic effect of chromium (iii) on the reduction of methylene blue byascorbic acid in acidic media. the reaction monitored smectrophotomenically by measuring the decrease ofabsorbance at 664 nm at 25 c. the fixed-time method was used for the first 300 s...
Among the environmental pollutants, heavy metals according to their irresolvable and physiological effects on living organisms at low concentrations, are of special importance These elements due to low mobility are gradually accumulated in soil Being accumulated in soil, they eventually enter the food chains and threaten human health and other creatures Therefore, studying concentration distrib...
We used an established isotope dilution gas chromatography-mass spectrometry method to measure blood volumes with an enriched stable isotope of chromium. The results were compared with those of the conventional method, which involves radioactive 51Cr. The two methods were compared simultaneously in two male subjects of different sizes, and essentially identical volumes were obtained. The isotop...
An accurate and precise method for direct determination of chromium in wine using graphite furnace atomic absorption spectrometry (GFAAS) is described. The method was also applied to grape samples treated by previous acid mineralization. A total of 79 wine samples from different regions in France and 12 grape samples of different varieties were analyzed. Chromium levels ranged from 7.0 to 90.0 ...
A method is described for assessing occupational exposures to chromium aerosols; it involves four procedures. The first, proton induced X-ray emission (PIXE), measures the total chromium. The second, electron spectroscopy for chemical analysis (ESCA), measures the oxidation state of the particle surfaces, and the third, which uses sym-diphenylcarbazide (DPQ, measures the proportion of water-sol...
Focus of this paper is the description of common used methods for hexavalent chromium measurement. This work is focused especially on commonly available spectrophotometric method based on the reaction with 1,5-diphenylcarbazide, because not every laboratory is equipped with modern devices for this pollutant measurement,. Special attention was focused on the variability possibilities of the basi...
A rapid and sensitive method has been proposed for the sequential determination of chromium(III) and total chromium in water samples by flame atomic absorption spectrometry combined with a flow injection on-line preconcentration on a double-microcolumn. The chromium(III) and total chromium in samples were retained on a double-microcolumn with a cation exchange resin, respectively, and eluted di...
A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg·Kg of w...
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