Comparison of Flow Injection and Continuous Sample Introduction for Automatic Simultaneous Determination of As, Sb, and Se by Hydride Generation and Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

The determination of As, Sb, and Se using flow injection sample introduction, hydride generation, and inductively coupled plasma optical emission spectrometry has been studied. Measurements were made with the use of a simultaneous three-channel system and compared with continuous hydride generation using the same detection system. In general, peak signals obtained with the flow injection system, with 750-μL injections, were approximately three times lower than steady-state signals for the continuous introduction system. Detection limits obtained by flow injection (As, 3.5 μg/L; Se, 3.6 μg/L; Sb, 7.0 μg/L) were also approximately three times poorer than they were for continuous introduction. By contrast, precision was approximately 150% better with flow injection, due to reduced pump pulsations in the flow injection system. Other advantages of the flow injection system are the reduced sample size necessary for analysis (≤750 μL vs. 4 to 5 mL for the continuous introduction system) and the potential for a greatly increased rate of sample throughput. Recovery studies with surface water samples showed acceptable accuracy for the flow injection system.