Determination of phosphorus and arsenic in trichlorosilane by electrothermal vaporization-inductively coupled plasma mass spectrometry with prior concentration by cuprous chloride.

A method for the determination of trace impurities of phosphorus and arsenic in trichlorosilane with prior separation followed by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed. The preconcentration of the analytes from the sample matrix was made by adding cuprous chloride to a 10 mL trichlorosilane sample for the formation of non-volatile compounds with the elements of interest. Upon evaporation of trichlorosilane, the analytes retained in the residue were then determined in the presence of copper as modifier by ETV-ICP-MS. The dual role of cuprous chloride both in the preconcentration and instrumental determination was investigated and discussed. By meticulous control of experimental conditions, limits of detection for these two elements as low as sub-ng/g can be achieved. The method was applied to the determination of phosphorus and arsenic in a commercially available trichlorosilane sample.