Development and optimisation of atom cells for sensitive coupled gas chromatography-flame atomic-absorption spectrometry

Abstract

The development of four novel atom cells for the determination of volatile organometallic compounds by coupled gas chromatography-flame atomic-absorption spectrometry is described. Tetraalkyllead compounds provided a model system in the optimisation of the four atom cells by the variable step-size simplex method. The effects of the various parameters on analytical performance are discussed. In the most sensitive system presented the effluent from the chromatograph was fed to a small hydrogen diffusion flame and the atoms from this flame were swept into a flame-heated ceramic tube. This simple, readily demountable arrangement enjoys the advantages of continuous operation associated with flames but, because of the relatively long atomic residence times, gave detection limits of 17 pg for both tetraethyl- and tetramethyllead. These limits are superior to any previously reported for a gas chromatographic-atomic-absorption spectrometric technique, including those employing electrothermal atomisation.