Behavior of several lead compounds in organic medium with a hydride generator. Direct determination of lead in gasoline

Abstract

A study was carried out with atomic absorption spectrometry (AAS), using a silica tube, to determine whether lead hydride could be generated In organic medium, using solvents N,Ndimethylformamlde, formamide, and dimethyl sulfoxide. Pb-(N03)2 was used as a standard of Pb(II) and Pb02, Pb(C2-H302)4, and PbR4 (where R = CH3 or C2H5) were used as standards for Pb(IV). It was found that even with wide ranges of NaBH4 concentrations, type and concentration of the acid medium, and various oxidants, no plumbane Is generated. However, the hydrogen given out In the decomposition of NaBH4 carries the tetraalkyl compound to the silica tube. This tetraalkyl compound can be carried to the silica tube by C02, generated In situ by adding NaHCOg In acid medium, Instead of using NaBH4. This permits the determination of volatile organometallic lead. The optimal conditions for direct volatilization of PbR4, delivery to the silica tube, and AAS measurement were determined. The detection limit was found to be 17 ppb of Pb In a 20-mL sample. The relative standard deviation Is 2.31 %. Pb was directly determined In several gasoline samples.The widespread use of organometallic compounds as antiknock agents in gasolines has added considerably to the amount of lead in the environment. This element, whose toxicity is well-known, is found in the environment in many different forms: lead oxide, metallic lead, and different alkyllead compounds.Methods have been developed for speciating alkyllead derivatives. Messman et al. (!) used a combination of liquid chromatography and atomic absorption spectrometry (AAS) to differentiate between tetramethyl-, trimethylethyl-, dimethyldiethyl-, methyltriethyl-, and tetraethyllead compounds in gasoline, and Walter et al.(2) combined gas chromatography and AAS to analyze these compounds independently.

Determination of lead in wine and rum samples by flow injection-hydride generation-atomic absorption spectrometry

“…The hydride generation has been used for determination of Pb in gasoline [23] and in chloroform extracts of lead pyrrolidine-1-carbodithioate from particulate matter [24]. A great deal of effort has been spent to develop a robust and reliable method for analysis of alcoholic beverages, such as wine.…”