No abstract

In this study, a method of pretreatment and speciation analysis of mercury by dispersive liquid-liquid microextraction along with CE was developed. The method was based on the fact that mercury species including methylmercury (MeHg), ethylmercury (EtHg), phenylmercury (PhHg), and Hg(II) were complexed with 1-(2-pyridylazo)-2-naphthol to form hydrophobic chelates and L-cysteine could displace 1-(2-pyridylazo)-2-naphthol to form hydrophilic chelates with the four mercury species. Factors affecting complex formation and extraction efficiency, such as pH value, type, and volume of extractive solvent and disperser solvent, concentration of the chelating agent, ultrasonic time, and buffer solution were investigated. Under the optimal conditions, the enrichment factors were 102, 118, 547, and 46, and the LODs were 1.79, 1.62, 0.23, and 1.50 g/L for MeHg, EtHg, PhHg, and Hg(II), respectively. Method precisions (RSD, n = 5) were in the range of 0.29-0.54% for migration time, and 3.08-7.80% for peak area. Satisfactory recoveries ranging from 82.38 to 98.76% were obtained with seawater, lake, and tap water samples spiked at three concentration levels, respectively, with RSD (n = 5) of 1.98-7.18%. This method was demonstrated to be simple, convenient, rapid, cost-effective, and environmentally benign, and could be used as an ideal alternative to existing methods for analyzing trace residues of mercury species in water samples.

Simultaneous analysis and removal of various heavy metal ions has received increasing concerns because they are usually co-existent with different toxicological effects. Ion imprinted polymers (IIPs) can effectively identify water-soluble ions especially heavy metal ions, however, multi-ion imprinting is rarely performed owing to possible cross-reactivity and matrix interferences. In this work, a novel and generally applicable IIPs strategy was proposed for simultaneous preconcentration and removal of four heavy metal ions based on dithizone chelation. Multi-ion imprinted polymers (MIIPs) embedded in a sol-gel matrix were prepared by using Hg Consequently, the MIIPs were used as solid-phase extraction sorbents for preconcentration of trace Hg 2+ , Cd 2+ , Ni 2+ and Cu 2+ , presenting high detectability up to 6.0-22.5 ng L À1 and satisfactory recoveries ranging from 94.7-110.2% in seawater samples. The developed MIIPs-based method proved to be a practically feasible method in heavy metal removal and water pretreatment.

Ochratoxin A (OTA) is a well-known carcinogenic contaminant in food commodities. Highly sensitive and specific detection of OTA level is an essential way to prevent health risk of human/animal. In...

On the basis of the basic feature of the electron transfer reactions, a new theoretical scheme and application of a nonempirical ab initio method in computing the inner-sphere Ž . reorganization energies RE of hydrated ions in electron transfer processes in solution Ž . are presented at valence STO basis VSTO level. The potential energy surfaces and the various molecular structural parameters for transition metal complexes are obtained Ž . using nonempirical molecular orbital MO calculations, and the results agree very well with experimentally observed ones from vibrational spectroscopic data. The results of inner-sphere REs obtained from these calculations via this new scheme give a good agreement with photoemission experimental findings and those from the improved 2q Ž . . and Co redox couple systems and are better than those from semiempirical INDOrII MO method and other classical methods. Further, the observed agreement of the optimized structural data and the results of inner-sphere REs of complexes with Ž . experimental findings confirms the following: 1 the validity of nonempirical MO calculation method to get accurate structural parameters and inner-sphere RE for the Ž . redox systems for which reliable vibrational spectroscopic data are not available, 2 the Ž . validity of the improved self-exchange model proposed early for inner-sphere RE, and 3