Arsenic compounds, selective volatilization

Arsenic (mfz 75) is known to suffer from an isobaric interference caused by the presence of ArCl+ (m/z 75) during speciation analyses, particularly for samples that contain a high chloride salt content, e.g., sea water and urine. Several groups [37-39] used hydride generation to transform the arsenic compounds into their volatile hydrides before aspiration into the ICP. Selective transportation of the hydrides may thus be achieved by using a gas-liquid separator to eliminate the chloride interference (Fig. 10.6). 

Several analytical methods for speciating arsenic have been reported. They include chromatographic techniques such as electrophoresis and ion-exchange (17), paper chromatography (18) and HPLC (19) selective volatilization of arsenic compounds to analogous arsines followed by GC-MES (20) boiling point separation/spectral emission (21) and atomic absorption (22). The above techniques have been applied to samples such as commercial pesticides (20),coal and fly ash (23),rocks, sediments, soils and minerals (24, 22),plant tissue (18), bovine liver (23),and water samples T25). 

The ores are blended with Na2C03 and KNO3, then roasted. Part of the S and As are removed as volatile compounds, leaving Co, Ni, and Cu oxides, with some sulfates, and arsenates. The sulfates and arsenates are leached with HOH, then the oxides are dissolved in hot H2SO4. The solution is treated with the oxidant NaClO, and the hydroxides are selectively precipitated by careful... 

As mentioned above in the context of the analysis of hgnin degradation products, gas chro-matography/mass spectrometry and related methods have been developed as extremely powerful tools for the identification of phenolic compounds. Use of high-pressure liquid chromatography in combination with mass spectrometry adds to the analytical arsenal with respect to the detection of polar, non-volatile compounds but, in particular, the advent of modem ionization techniques, such as ESI and MALDI mass spectrometry, have continued to broaden the analytically governable field of organic chemistry. The latter methods diminish the need of derivatization of polar phenolics to increase the volatility of the analyte. In this section, a more or less arbitrary selection of examples for the application of mass spectrometric techniques in analytical chemistry is added to the cases already discussed above in the context of gas-phase ion chemistry. 

In 2003, urban air pollution was monitored at 76 stations (44 and 32 operated by the Ministry of Health and the Ministry of the Environment, respectively) located in 27 cities involved in the Monitoring System (SZU, 2004). In 2003, sulphur dioxide (SO2), nitrogen oxides (NO/N02/NOx), particulate matter (TSP and/or suspended PMio fractions), and mass concentrations of selected metals (arsenic, chromium, cadmium, manganese, nickel and lead) in particulate matter samples were monitored in all the cities of the Monitoring System except for Melnik. The SO2 measurements in the Public Health Service network were terminated at all the manual stations in the cities with CHMI stations in the cities without a CHMI station, measurements are made during the heating season only). Concentrations of carbon oxide, ozone, polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) continue to be monitored selectively in a number of the monitored cities. 

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