Determination of Hg2+ by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry

Abstract

A simple and sensitive method to determine Hg2+ was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized l-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg2+ elution conditions, namely, an FI flow rate of 2.0mLmin−1 and an eluent comprised of 10% thiourea in 0.2molL−1 HNO3. The detection limit of FI–SCGD-AES was determined to be 0.75μgL−1, and the precision of the 11 replicate Hg2+ measurements was 0.86% at a concentration of 100μgL−1. The proposed method was validated by determining Hg2+ in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310).