Vapor generation coupled with furnace atomization plasma emission spectrometry for detection of mercury

A low power atmospheric pressure plasma source, furnace atomization plasma emission spectrometry (FAPES), was directly coupled to both a conventional chemical vapor generation system based on use of tin chloride reductant as well as a UV-photoreduction system for detection of cold vapor mercury. The resonance line emission at 253.7 nm was monitored. The 70 W low power He plasma was tolerant to the introduction of water vapor from the gas–liquid separator and, with the furnace heated to 400 °C, a precision of measurement of 2.4% RSD at 1 ng mL−1 was achieved. A limit of detection of 250 pg mL−1Hg in river water samples via UV-photoreduction and 240 pg mL−1 using conventional tin chloride reduction was obtained. The LOD could be improved 5-fold through use of a simple gold amalgamation system. Conventional chemical generation of mercury using the NaBH4/HCl system produced too much hydrogen to permit efficient coupling to the FAPES source as the He plasma is extinguished by the load of molecular vapor (i.e., hydrogen).