D. Chakraborti

Graphite-furnace atomic absorption spectrometry as a metal-specific detection system for tetraalkyllead compounds separated by gas—liquid chromatography

Abstract The use of a gas—liquid chromatograph in combination with a graphite-furnace atomic absorption spectrometer is described for the determination of tetraalkyllead compounds. Various important analytical parameters affecting the sensitivity and precision are discussed. Absolute detection limits range between 40 pg for tetramethyllead and 90 pg for tetraethyllead. For all species the reproducibility is better than 2% at the nanogram level. The absolute selectivity is demonstrated by the analysis of gasoline samples, including the National Bureau of Standards gasoline standards reference material.

The determination of arsenic by electrothermal atomic absorption spectrometry with a graphite furnace : Part 1. Difficulties in the direct determination

Abstract The direct determination of arsenic by graphite-furnace atomic absorption spectrometry is critically examined. Matrix stabilization by nickel salts is effective for preventing charring losses of arsenic, but cannot eliminate strong interferences. Direct analysis of environmental and biological samples is impossible because of the presence of aluminium, sodium, potassium and sulphates.

The determination of arsenic by electrothermal atomic absorption spectrometry with a graphite furnace: Part 2. Determination of arsenic(III) and arsenic(V) after extraction

Abstract A procedure is described for the sequential determination of arsenite and arsenate in samples of natural waters. It is based on the extraction of arsenic(III) with ammonium sec-butyl dithiophosphate and measurement, after re-extraction into water, by graphitefurnace atomic absorption spectrometry. Reduction of arsenic(V) allows its subsequent determination. The method is applied to fresh and sea water samples. The detection limit is 6 ngl-1.

Occurrence of tri- and dialkyllead species in environmental water.

Rain, snow, and surface water was sampled in or near Antwerp, Belgium. The ionic alkyllead compounds were extracted as diethyldithiocarbamates, enriched, derivatized with n-butyl-Grignard reagent, and determined by using gas chromatography - atomic absorption spectrometry. In wet atmospheric deposition the individual tri- and di-alkyllead species tend to occur at the 10-100 ng.L/sup -1/ level. The highest concentrations (maximum 200 ng.L/sup -1/) were detected at busy traffic sites in the city center. The ratio of total ionic alkyllead to inorganic lead is ca. 0.07%, more or less independent of sampling site and time. In surface water, the trimethyllead concentration typically amounts to about 5 ng.L/sup -1/ whereas the dialkyllead species are generally present at a significantly lower level, below 1 ng.L/sup -1/. 25 references, 2 figures, 4 tables.

Speciation of ionic alkyllead in grass and tree leaves

Abstract A preliminary study aimed at outlining the potential of the extraction/derivatization/gas chromatography-atomic absorption spectrometry methodology for the species-specific determination of ionic organolead compounds in grass and tree leaves is described. A pretreatment procedure based on leaching the species from the matrix using tetramethylammonium hydroxide appeared to be efficient. In grass, concentrations up to 100 ng Pb g-1 were detected; a reliable differentiation between the amount taken up and the amount superficially adsorbed could not yet be achieved.

Speciation of ionic alkyllead in potable water and soil

Various potable water and soil samples have been analyzed for tri- and dialkyllead compounds using a sensitive speciation procedure based on diethyldithiocarbamate extraction, Grignard derivatization and gas chromatography-atomic absorption spectrometry. The species are generally present as ultra-trace contaminants, and their abundance is critically discussed. In addition, a degradation study of ionic alkyllead in ambient matrices is presented.

Speciation of ionic alkyllead in aerosols by gas chromatography-atomic absorption spectrometry

Abstract A sensitive method is described to determine the individual ionic alkyllead species associated with the air particulate matter fraction. The optimization of the procedure and the application to residential aerosols are discussed.

Occurrence of monoalkyllead species during the speciation of organolead

Abstract When tri-levels are determined in environmental samples by a method based on Grignard derivatization and subsequent gas chromatography/atomic absorption spectrometry, monoalkyllead species are sometimes detected. A rearrangement process during or following Grignard derivatization explains this occurrence at least partly. The accuracy of the determination does not suffer significantly from this limited-scale reaction but the detection of a monoalkyltributyllead species does not necessarily mean that the sample contains monoalkyllead compounds.

Factors influencing sensitivity and accuracy for the determination of alkylselenides and tetra alkyllead compounds by gas chromatography/atomic absorption spectrometry

Abstract Factors affecting the quantitative collection of dimethylselenide, diethylselenide and dimethyldiselenide, as well as of tetraalkyllead compounds fromt he air by the cryogenic trap technique and their determination, by gas chromatography/atomic absorption spectrometry are described. Flash injection (and the addition of ca 10% of hydrogen to the carrier gas0 provide a highly sensitive detection.

Ionic alkyllead compounds in environmental water and sediments

To elucidate the occurrence and fate of ionic alkyllead species in environmental water and sediments, a procedure, based on the existing methodology for speciation of lead in the biosphere, has been optimized. It allows species-specific detection of the degradation products of tetraalkyllead at levels down to 150 pg · L−1 in water or 25 pg · g−1 in sediment.