title: Speciation analysis of mercury in water samples by dispersive liquid-liquid microextraction coupled to capillary electrophoresis.
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 μg/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.
authors.affiliation: College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, P. R. China; Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, P. R. China.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Yang
authors.forename: Jinhua
authors.initials: J
authors.lastname: Li
authors.forename: Wenhui
authors.initials: W
authors.lastname: Lu
authors.forename: Yingying
authors.initials: Y
authors.lastname: Wen
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Cai
authors.forename: Jinmao
authors.initials: J
authors.lastname: You
authors.forename: Jiping
authors.initials: J
authors.lastname: Ma
authors.forename: Yangjun
authors.initials: Y
authors.lastname: Ding
authors.forename: Lingxin
authors.initials: L
authors.lastname: Chen
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D057230:Limit of Detection; D016014:Linear Models; D059627:Liquid Phase Microextraction / Q000379:methods*; D008628:Mercury / Q000032:analysis* / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification; D009284:Naphthols / Q000737:chemistry; D009941:Organomercury Compounds / Q000032:analysis* / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification; D015203:Reproducibility of Results; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification
chemical_list: D009284:Naphthols; D009941:Organomercury Compounds; D014874:Water Pollutants, Chemical; C041728:1-(2-pyridylazo)-2-naphthol; D008628:Mercury
keywords: Capillary electrophoresis; Dispersive liquid-liquid microextraction; Mercury speciation; Water sample