Selective pre-concentration of arsenite on mercapto-modified silica gel

Abstract

A surface-modified silica gel has been developed for the pre-concentration of arsenite from natural waters. The reaction of silica gel with (3-mercaptopropyl)trimethoxysilane produces a mercapto-modified silica gel with a silver capacity of ca. 0.9 mmol g^–1. This material selectively removes arsenite from samples that also contain arsenate, monomethylarsonate and dimethylarsinate, and can be employed for both the column and batch pre-concentration of arsenite. Under column and batch conditions recoveries of ca. 96 and 94% are obtained but reproducibility is better for the column technique.