Search results for "Mercury"
showing 10 items of 396 documents
Development of an ICP-IDMS method for accurate routine analyses of toxic heavy metals in polyolefins and comparison with results by TI-IDMS
2000
An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method was developed as a suitable method - with respect to its sensitivity, precision, accuracy, and time-consumption - for the analysis of toxic heavy metal traces (Pb, Cd, Cr, and Hg) in polyolefins. Results for Pb, Cd, and Cr were compared with those obtained by thermal ionization isotope dilution mass spectrometry (TI-IDMS), which was used as a reference method. Because of its high first ionization potential and its high volatility mercury could not be determined by TI-IDMS. A multi-element spike solution, containing isotopically enriched 206Pb, 116Cd, 53Cr, and 201Hg, was used for the isotope dilution step. D…
Determination of mercury in rice by cold vapor atomic fluorescence spectrometry after microwave-assisted digestion.
2010
Abstract A cold vapor atomic fluorescence spectrometry method (CV-AFS) has been developed for the determination of Hg in rice samples at a few ng g−1 concentration level. The method is based on the previous digestion of samples in a microwave oven with HNO3 and H2O2 followed by dilution with water containing KBr/KBrO3 and hydroxylamine and reduction with SnCl2 in HCl using external calibration. The matrix interferences and the effect of nitrogen oxide vapors have been evaluated and the method validated using a certified reference material. The limit of detection of the method was 0.9 ng g−1 with a recovery percentage of 95 ± 4% at an added concentration of 5 ng g−1. The concentration level …
Non-chromatographic speciation of mercury in mushrooms
2016
A fast, sensitive and cheap procedure has been developed for the determination of inorganic mercury (i-Hg) and organic mercury (o-Hg) in mushroom samples. The procedure is based on the use of cold vapour atomic fluorescence spectrometry (CV-AFS). The method involves the extraction of total mercury (t-Hg) with diluted HCl, followed by measurements of the corresponding Hg vapour under two different conditions: (i) directly to determine i-Hg, and (ii) after oxidation with a mixture KBr/KBrO3 to determine t-Hg. o-Hg was estimated from the difference between t-Hg and i-Hg. Previous studies were focused on the assessment of different reagents for mercury extraction and breakdown of organomercury …
Determination of total mercury in nuts at ultratrace level
2014
Abstract Total mercury, at μg kg−1 level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7 μg kg−1 by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633…
Study on the determination of trace rhenium (VII) by the adsorption differential pulse polarography
1989
The determination of trace rhenium (VII) by differential pulse polarography in the system of H2SO4-(NHsOH)2 · H2SO4-TeO2−4 is markedly improved by the addition of Nitron, which is adsorbed on the surface of mercury electrode. The limit of detection is down to 2 × 1010 M. The adsorptive peak potential is −0.80 V (vs. SCE). In the ranges of 5 × 1010—10−8, 1 × 10−5—10−7 and 1 × 10−7—10−6M, there are good linear relationships between the peak current increment and the concentration, of which the relative standard deviations are 9.5, 6.6, 1.8% respectively with the correlation coefficients of linear regression of 0.995–0.999. The results relating to this polarographic wave show that it is an ads…
Spectrophotometric determination of mercury(II) and silver(I) with copper(II) and diethyldithiocarbamate in the presence of triton X-100
1986
Abstract Procedures for the determination of mercury and silver by displacement of diethyldithiocarbamate (DDTC) from its copper complex in the presence of 1% Triton X-100, and measurement of the decrease in the Cu(DDTC) 2 absorbance, are described. The use of the surfactant avoids the need for an extraction step. Reproducibility within 1% and detection limits of 0.25 ppm Hg(II) and 0.45 ppm Ag(I) have been obtained, and linear calibration ranges up to 13 ppm Hg(II) and 15 ppm Ag(I). In the presence of 0.1 M EDTA very good selectivity is achieved.
Methylmercury and inorganic mercury determination in fish by cold vapour generation atomic absorption spectrometry
2000
Abstract Given that organic mercury is more dangerous than the inorganic form and that it is converted into methylmercury by biological methylation, we have studied and optimized a simple method for measuring both organic and inorganic mercury contents in fish, using a spectroscopic vapour generation technique, with a sequential reduction of the digested sample with stannous chloride and sodium tetrahydroborate. Prior to applying the method the sample was subjected to alkaline wet digestion. Due to the matrix interferences calibration curves with matrix addition were needed for mercury determinations. The analytical parameters of the method were: linearity from 10 to 200 ng of Hg in the red…
Voltammetric behavior and assay of the contraceptive drug levonorgestrel in bulk, tablets, and human serum at a mercury electrode.
2004
The cyclic voltammograms of levonorgestrel (LNG) in Britton-Robinson buffers of pH 2-11 at the hanging mercury drop electrode showed a single two-electron irreversible cathodic peak over the whole pH range. This peak may be attributed to the reduction of the 3-keto-delta-4-group in the A-ring of the LNG molecule. The interfacial adsorptive character of levonorgestrel onto the surface of the hanging mercury drop electrode was identified by means of both cyclic voltammetry and chronocoulometry techniques. A simple, sensitive, and selective square-wave adsorptive cathodic stripping voltammetric procedure was developed for the quantitation of levonorgestrel. Under the optimized operational cond…
3D and multispectral imaging for subcutaneous veins detection.
2009
The first and perhaps most important phase of a surgical procedure is the insertion of an intravenous (IV) catheter. Currently, this is performed manually by trained personnel. In some visions of future operating rooms, however, this process is to be replaced by an automated system. Experiments to determine the best NIR wavelengths to optimize vein contrast for physiological differences such as skin tone and/or the presence of hair on the arm or wrist surface are presented. For illumination our system is composed of a mercury arc lamp coupled to a 10nm band-pass spectrometer. A structured lighting system is also coupled to our multispectral system in order to provide 3D information of the p…
Effects of docosahexaenoic acid and methylmercury on child's brain development due to consumption of fish by Finnish mother during pregnancy: A proba…
2011
Abstract Fish contains both beneficial substances e.g. docosahexaenoic acids but also harmful compounds e.g. methylmercury. Importantly, the health effects caused by these two substances can be evaluated in one common end point, intelligence quotient (IQ), providing a more transparent analysis. We estimated health effects of maternal fish consumption on child’s central nervous system by creating a model with three alternative maternal fish consumption scenarios (lean fish, fatty fish, and current fish consumption). Additionally, we analyzed impacts of both regular fish consumption and extreme fish consumption habits. At the individual level, the simulated net effects were small, encompassin…