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

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 2.0 mL min(-1) and an eluent comprised of 10% thiourea in 0.2 mol L-1 HNO3. The detection limit of FI-SCGD-AES was determined to be 0.75 mu g L-1, and the precision of the 11 replicate Hg2+ measurements was 0.86% at a concentration of 100 mu g L-1. The proposed method was validated by determining Hg2+ in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310). (C) 2014 Elsevier B.V. All rights reserved.