Determination Of Mercury Speciation In Water By High Performance Liquid Chromatography Hydride Generation Atomic Fluorescence Spectrometry

Object Mercury,which belong to highly toxic substances,is one of the most poisonous heavy metals in the natural environment.China is the largest country for mercury emissions which can circulate and migrate into the environment.Then the surface water which was closely related to human life were polluted inevitably.However,the toxicity of mercury compounds was closely related to their morphology.The toxicity of organic mercury was higher than the inorganic forms.There are three primary forms of mercury in water sample:the bivalent mercury(Hg²⁺),methyl mercury?MeHg?and ethyl mercury?EtHg?.The methyl mercury among them is the most poisonous.The toxicity of mercury varies greatly from form to form.Nowadays research on mercury tends to morphology.At present,the limits of domestic drinking water and surface water in China are calculated on the basis of total mercury.However the determination of total mercury can't assess the actual harm of mercury scientifically.In this paper,the main is to establish a method for the determination of mercuric species in water by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry.The established method can be used to detect mercury species and applied in water samples from 10 different areas,which can also provide technical support for establishing standard detection method and health standard for mercury species in the future.Method Three forms of mercury were separated by C₁₈ reversed phase column in HPLC.The Hg²⁺,MeHg and EtHg were orderly determined by hydride generator-atomic fluorescence spectrometer after extracted from C₁₈ reversed phase column and later oxidized in the UV On-line digestion.Three forms of mercury were qualitative by the retention time and quantitative by peak area with external standard method.The optimized experimental conditions were tested and selected by single factor rotation method and orthogonal design method.And the detection limit,linear range,precision,accuracy and sample stability of the method were analysed and discussed in the study.The established method was used to detect 40 samples of water in river,lake and well under the optimal conditions,which were collected by volunteers from10 different areas.The uncertainty of the results of water samples were evaluated to ensure the reliability and accuracy of the test results.At the same time the accuracy and practicability of the established method were evaluate by measurement of actual water samples.Results The mobile phase was composed by 3%carbinol,70mmol/L ammonium acetate and 1.0g/L L-cysteine.The concentration of oxidizing agent were 10g/L for potassium persulfate and 5g/L for potassium hydroxide.The concentration of reducing agent were 5g/L for potassium borohydride and 5g/L for potassium hydroxide.The carrier liquid is 10%of nitrate acid.The on-line ultraviolet digestion device was used in the study.The conditions for atomic fluorescence spectrometry were 330V for negative high voltage,50mA for lamp current,700ml/min on carrier gas flow rate and 300ml/min on shielding gas flow rate.Under the above conditions,the correlation coefficients of standard curves for the three mercury species were all greater than 0.999.The three kinds of mercury were separated completely,and the chromatographic peaks were not disturbed.The detection time was short and fluorescent response was high.The linearity of the method were good for divalent mercury?y=197.32x+68.345?,methyl mercury?y=254.52x-53.162?and ethyl mercury?y=270.79x-84.555?.The detection limits were 0.21?g/L,0.64?g/L and0.72?g/L and the linear range were 0.21?g/L¹0.00?g/L,0.64?g/L¹1.00?g/L,0.72?g/L¹1.22?g/L for them respectively.The average recovery were 91.21%¹09.33%and the RSD of precisions were between 2.52%and 6.76%for the method.In the study,40 water samples were detected by the established method in which only one water sample was detected the bivalent mercury with concentration of 2.41?g/L.ConclusionThestudyestablishedahighperformanceliquid chromatography-hydride generation-atomic fluorescence spectrometry for the determination of mercury species in natural environment water.The single factor rotation method and the orthogonal design method were used to decision the best detecting condition such as mobile phase,the concentration of the carrier solution,the oxidant agent and reducing agent,UV on-line digestion device,negative high voltage,lamp current and carrier gas flow.The determination method of mercury species in water by HPLC-HG-AFS was simple,high-efficient and accurated which has the advantages of simple pretreatment,no digestion and direct filtration.In this study,the three forms of mercury had been separated betterly with a higher fluorescence response.It was suitable for speciation analysis of mercury in surface water and provided technical support for risk exposure assessment of mercury.This method could also be used for monitoring and analysing of mercury species in drink water samples and it was proved to have practical application value.