A ceramic microchip with LDA-APGD as the excitation source for OES - a sensitive Hg detecting sensor for microsample analysis

摘要

A novel portable excitation microsource for optical emission spectrometry (OES) based on atmospheric pressure glow discharge with a liquid drop anode (LDA-APGD), generated in a ceramic microchip (mch), was developed. This excitation microsource uses low temperature cofired ceramic (LTCC) microchips to provide electrical contact and fabricate a hollow to hold a microsample solution. Optimization of this new excitation source was performed for the quantification of Hg in liquid samples and discussed. Optimal parameters for Hg determination were: polarized liquid drop - anode, discharge current - 80 mA, solution drop volume - 15 μL, He flow rate - 300 mL min~(-1), chip hollow dimensions: diameter 3.0 mm and depth 0.6 mm, HNO_3 concentration - 0.10 mol L~(-1). The addition of low molecular weight organic compounds (LMWOCs) to the solution was also tested. The linearity range for mch-LDA-APGD was up to 30 mg L~(-1), and the limit of detection (LOD) of Hg was 47 μg L~(-1). Precision of this method was within 0.65-8.7% (as the relative standard deviation of repeated measurements). Recoveries obtained for tap water samples spiked with Hg(Ⅱ) ions at 100, 200, and 300 μg L~(-1) were within the range of 96-122%.