Sensitive and ultra-fast determination of arsenic(III) by gas-diffusion flow injection analysis with chemiluminescence detection.

A novel chemiluminescence gas-diffusion flow injection system for the determination of arsenic(III) in aqueous samples is described. The analytical procedure involves injection of arsenic(III) samples and standards into a 0.3 mol L(-1) hydrochloric acid carrier stream which is merged with a reagent stream containing 0.2% (w/v) sodium borohydride and 0.015 mol L(-1) sodium hydroxide. Arsine, generated in the combined carrier/reagent donor stream, diffuses across the hydrophobic Teflon membrane of the gas-diffusion cell into an argon acceptor stream and then reacts with ozone in the flow-through chemiluminescence measuring cell of the flow system. Under optimal conditions, the method is characterized by a wide linear calibration range from 0.6 microg L(-1) to 25 mg L(-1), a detection limit of 0.6 microg L(-1) and a sample throughput of 300 samples per hour at 25 mg L(-1) and 450 samples per hour at 25 microg L(-1).