On-line adsorption/preconcentration using a knotted reactor for total Hg determination in drinking water by flow injection CV-AAS

Abstract

An on-line mercury pre-concentration and analysis system using atomic absorption spectrometry (AAS) and flow injection (FI) with cold vapor (CV) generation was studied. The mercury was retained as a mercury-2-(5-bromo-2-pyridylazo)-5-diethplaminophenol [Hg(II)-(5-Br-PADAP)] complex, at pH 9.2. The mercury complex was removed from the knotted reactor (KR) with 3 mol/L hydrochloric acid. An enrichment factor of 25 was obtained with respect to CV AAS. The detection limit for the pre concentration of 25 ml, aqueous solution was 5 ng/L. The precision, calculated at peak height for 10 replicate determinations at the 1 µg/L-Hg level, was 2.8% relative standard deviation (RSD): The calibration curve using;. the pre-concentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limits up to at least 100 µg/L. The method was successfully applied to the determination of mercury in drinking water samples.