DETERMINATION OF TRACE-ELEMENTS IN TRIMETHYLGALLIUM BY ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY AND INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

Three different methods are described for the determination of trace elements in trimethylgallium (TMG), involving the use of electrothermal atomisation atomic absorption spectrometry (ETAAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The TMG, diluted with xylene, was decomposed by its gradual addition to cooled hydrochloric acid in an atmosphere of argon. The gallium-free xylene phase obtained by the decomposition was used for the determination of organic silicon by ICP-AES. Inorganic silicon in the hydrochloric acid phase was determined by ETAAS, with the use of a lanthanum-coated graphite tube, after the concentration of inorganic silicon by diisopropyl ether extraction and lanthanum hydroxide coprecipitation techniques. Thirteen other elements were also determined by ETAAS after the separation of gallium by diisopropyl ether extraction. Detection limits for organic silicon, inorganic silicon and the other elements were 0.02, 0.05 and 0.01 p.p.m., respectively.