Movable reduction bed hydride generation system as an interface for capillary zone electrophoresis and inductively coupled plasma atomic emission spectrometry for arsenic speciation analysis†

Abstract

Hydride generation can significantly improve the detection limits for a number of hydride-forming elements with atomic spectrometric determination. In order to harmonize the microliter level eluates from capillary electrophoresis and the milliliter sample volume commonly needed in ICP-AES, a specially designed technique, ‘movable reduction bed hydride generation’ has been developed, which is simple to operate and carries out the hydride generation for micro-sample volume without the use of a gas–liquid separator or the addition of an acid dehydrator. The technique can be used to convert arsenic compounds from capillary zone electrophoresis (CZE) separation to corresponding volatile hydrides followed by ICP-AES analysis. The separation characteristics of arsenic species by CZE are presented, including the optimization of experimental parameters such as pH, concentration of buffer solution, as well as sample injection volume. The RSDs of peak area for four arsenic species range from 1.9 to 11.7%. The detection limits for AsIII, disodium methylarsonate and AsV are 0.32 µg ml^–1, and 0.35 µg ml^–1 for dimethylarsinic acid.