Loss of di- and trimethylarsine on Nafion membrane dryers following hydride generation

Abstract

Complete loss of trimethylarsine upon passage through a Nafion membrane dryer was identified. Pronounced loss of dimethylarsine—19 and 66%, depending on dryer dimensions—was also observed; arsine and methylarsine did not exhibit significant losses. Arsines were generated from corresponding precursors at the 2 ng ml⁻¹ level by tetrahydroborate reduction, after passing through the dryer separated by cryotrapping and thermal desorption and detected by atomic absorption spectrometry with a quartz multiatomizer. Since Nafion membrane dryers have been commonly used in analytical atomic spectroscopy, implications for trace and speciation analysis of arsenic are discussed. A dryer based on sodium hydroxide pellets is proposed as an alternative, safe for all arsines.