| With the rapid economic development, the increasing usage of heavy metals enhanced their pollution in the environmental and biology field. Studies of heavy metal pollution and harm have been one of the most important research topics in food and environment. The toxicity of different element forms varied greatly which affected the physiological, toxicological and environmental behavior of the organisms. The studies of lead and mercury could no longer limit to the determination of their total contents; the speciation analyses of them need much more attentions. Furthermore, simple, efficient and environmentally friendly preconcentration methods play an important role in the speciation analysis owing to the low content and the complex matrices of the heavy metals.A method for the rapid speciation of four mercury species by high performance liquid chromatography(HPLC) hyphenated with inductively coupled plasma mass spectrometry(ICPMS) was established. Effective separation of inorganic mercury(Hg2+), methylmercury(MeHg), ethylmercury(EtHg) and phenylmercury(PhHg) within 3 min was achieved on the reversed phase C18 column with 0.1% L-cysteine, 2 mmoL ammonium acetate and methanol(pH=6.8) as the mobile phase at gradient elution mode. The detection limits for Hg2+, MeHg, EtHg and PhHg were 0.06 μg/L, 0.05 μg/L, 0.08 μg/L and 0.06 μg/L, respectively. The linear relationship of the four mercury species with the linear range from 0.5 μg/L to 10 μg/L was good. Correlation coefficients of four mercury species were higher than 0.9995. Contents of Hg species and total mercury in certified reference materials of human hair(GBW 07601), yellow croaker(GBW 08573) and tuna fish( ERM-CE464) tested by this method were in good accordance with the certified values. The developed method was applied for the speciation analysis of mercury in two water samples and three fish samples. Recoveries ranged from 95%-122% when tested at two levels(0.5 μg/L、5 μg/L) in the two water samples were obtained. The relative standard deviation(RSD)(5.0 μg/L for each Hg species) were all lower than 5%. Satisfactory results of comparing the contents of the mercury species in the two fish samples to the data from other Food Laboratory were gained.A hybrid method for the rapid speciation of lead compounds by reversed-phase high performance liquid chromatography(HPLC) separation and inductively coupled plasma mass spectrometry(ICP-MS) detection was reported. Effective separation of inorganic lead(Pb2+), trimethyllead(TML), triethyllead(TEL) and triphenyllead(TPhL) was achieved within 3.5 min on a C18 reversed-phase column using a programmed gradient of 5:95 to 90:10 methanol-water(containing 5 mg/L sodium 1-pentanesulfonate, pH = 5) eluent. The detection limits lead was 0.01 μg/L for inorganic lead, and 0.02 μg/L for the other three organic lead species. The accuracy of the method has been verified by testing the lead species in two certified reference materials, water(GSBZ 50009-88) and sea water(GBW(E) 080040). The method has also been applied on two real water samples and the inorganic lead was detected in the river water sample.On the basis of the speciation of lead and mercury respectively, in this section, a simple method for the simultaneous determination of four lead species and four mercury species was developed using gradient high-performance liquid chromatography(HPLC) coupled to inductively coupled plasma mass spectrometry(ICP-MS). Baseline separation of the eight species was achieved in less than 5 min on a C18 column at gradient elution in a single injection with 0.1% L-cysteine(pH 2.5) and methanol as the mobile phase. The method detection limits, defined as three times the standard deviation were found to be 0.01~0.03 μg/L for lead, 0.04 ~ 0.05 μg/L for mercury respectively. The method was validated on river and tap water samples(0.45 μm) which spiked with 0.5 μg/L and 5 μg/L(as Pb and Hg) of each species, and the recoveries ranging from 86 to 108 % were obtained.On account of the low content of lead and mercury species in the environmental and biolocical samples, on the basis of the previous works, the study of simultaneous cloud point extraction for lead and mercury species was investigated to broaden the utilization of this method. The decomposition of organic leads in cloud point extraction and the influence of pH, time, temperature and the concentration of DDTC and organic leads on the decomposition were discussed in detail. Because of the decomposition of organic leads, only the qualitative analysis of four lead species and two mercury species by HPLC-ICP-MS after simultaneous cloud point extration has been investigated in this study, and the baseline separation of these species was acheieved. The quantitative analysis of the method and its application remains to be further explore. |
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