A sensitive and compact mercury analyzer by integrating dielectric barrier discharge induced cold vapor generation and optical emission spectrometry

An environmentally friendly, low power consuming, sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced cold vapor reactor and a dielectric barrier discharge optical emission spectrometer into a small polymethyl methacrylate plate (10.5 cm length×8.0 cm width×1.2 cm height). Mercury cold vapor was generated when standard or sample solutions with or without formic acid were introduced to the reactor to form thin film liquid and exposed to microplasma irradiation and subsequently separated from the liquid phase for transport to the microplasma and detection of its atomic emission. Limits of detection of 0.20 μg L^-1 and 2.6 μg L^-1 were obtained for the proposed system using or not using formic acid, respectively. Compared to the conventional microplasma optical emission spectrometry used for mercury analysis, this system not only retains the good limit of detection amenable to the determination of mercury in real samples, but also reduces power consumption, eliminates the generation of hydrogen and avoids the use of toxic or unstable reductant. Method validation was demonstrated by analysis of a certified reference material of water sample and three real water samples with good spike recoveries (88-102%).