Determination of arsenic by hydride generation inductively coupled plasma mass spectrometry using a tubular membrane gas–liquid separator

Abstract

A silicone rubber membrane gas–liquid separator (MGLS) has been used to determine arsenic by hydride generation inductively coupled plasma mass spectrometry (ICP-MS). The use of a membrane separator eliminated the polyatomic ion interference of ArCl⁺ on As⁺, which is a significant interference in pneumatic nebulization ICP-MS and a residual problem with hydride generation using a conventional U-shaped gas–liquid separator. Optimum operating conditions for the MGLS were identified as 0.1% m/v sodium tetrahydroborate, 4 mol dm^–3 hydrochloric acid, 0.9 l min^–1 argon purge gas flow, 0.8 l min^–1 auxiliary gas flow and 1.8 kW forward power. Use of the MGLS enables the determination of arsenic in solutions of hydrochloric acid by ICP-MS. The arsenic content (25 ng ml^–1) of a reference water sample was successfully determined.