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%）.

Reduction of mercury(Ⅱ)by electrons contained in carbon dots:An environmentally friendly cold vapor generation for mercury analysis

In this work,the reduction of mercury ions(Hg2+)to elemental mercury(Hg0)was easily achieved using highly reductive carbon dots(r-CDs),which synthesized from sucrose by a simple and cost-effective method.After a careful mechanistic study,the reduction was probably accomplished with the large numbers of electrons contained in r-CDs rather than the oxidation of its functional groups.Additionally,a3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay showed that the r-CDs were nontoxic to wildlife and human beings.Consequently,the r-CDs were used as an alternative to toxic reductants(SnCl2 or NaBH4)for the sensitive and in situ determination of mercury by cold vapor gene ration(CVG)coupled to a miniature point discharge optical emission spectrometer(μPD-OES).Limit of detection of 0.05μg/L was obtained for Hg2+,with relative standard deviation(RSD)less than 5.4%at a concentration of 5μg/L.The accuracy of r-CDs induced CVG-μPD-OES was validated by the determination of mercury in a certified reference material(DOLT-5,dogfish liver)and five natural water samples collected from different rivers and lakes in Chengdu City,Since r-CDs are nontoxic and prepared from abundant and inexpensive sucrose,the r-CDs induced CVG-μPD-OES retains the great potential for the inexpensive and enviro nmentally friendly field analysis of mercury in natural water.The accuracy of the proposed method was validated by the analysis of a certified reference material and several water samples with satisfactory results.