On-line chloride interference removal for arsenic determination in waste water and urine by ICP-MS using a modified capillary

The determination of arsenic in environmental samples like waste waters from industrial effluents and in biological samples like urine is very important due to the toxic nature of some of its species at moderate levels, of exposure. The objective of this study was to evaluate the capability of modified anionic capillaries to remove chloride for ICP-MS determination of arsenic, which causes spectral interference due to formation of (ArCl+)-Ar-40-Cl-35. Also high chloride content gives non-spectral interferences. The results indicate that arsenic at a concentration higher than 1 mug L-1 in a matrix with a chloride content up to 600 mg L-1 can be accurately determined using a 3-aminopropyltrimethoxysilane (APTMS) modified capillary connected to a microconcentric nebuliser (MCN). The interference level of chloride is considerably reduced due to its retention in the capillary. The method has been successfully applied and validated for waste water and by recovery tests for urine (diluted 1 : 15) samples.