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

• A modified SBA-15 mesoporous silica (SH-SBA-15) was synthesized as a sorbent.
• On-line SPE combined with SCGD-AES based on FIA was used to detect Hg2+ firstly.
• A simple, low-cost Hg2+ analysis in a complex matrix was established.
• The sensitive detection of Hg2+ was achieved with a detection limit of 0.75 μg L−1.

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 μg L−1, and the precision of the 11 replicate Hg2+ measurements was 0.86% at a concentration of 100 μg L−1. The proposed method was validated by determining Hg2+ in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310).

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