Simultaneous determination of arsenic(III) and arsenic(V) by flow injection–inductively coupled plasma–atomic emission spectrometry (ICP-AES) with ultrasonic nebulization

Abstract.

A dual-column protocol for the sequential determination of As(III) and As(V) is described using inductively coupled plasma–atomic emission spectrometry (ICP-AES) with ultrasonic nebulization (USN). This procedure employed a 16-way valve containing two different homemade mini columns for selective preconcentration of As(III) and As(V). One column was filled with Muromac A-1, which selectively preconcentrated As(III) at pH 3 after complexation with ammonium pyrrolidine dithiocarbamate (APDC, 0.05%). The effluent of the first column was then passed through the second column, which was filled with an anion-exchange resin to collect As(V). By using 0.6 M sodium hydroxide, both species were eluted sequentially and measured by ICP-AES. Enrichment factors of 136 (17 for micro column ×8 for USN) for As(V) and 160 (20 for micro column ×8 for USN) for As(III) were achieved with 4 min preconcentration. With the proposed procedure, the detection limits were calculated to be 0.7 µg L^–1 for As(V) and 0.8 µg L^–1 for As(III) based on (3σ) blank determination (N=10). The relative standard deviations for 20 µg L^–1 of As(V) and As(III) were 5.8% and 6.5%, respectively. The recovery for spiked water samples was in the range of 85–112%.