Mercury Speciation Analysis In Environmental Sample By HPLC-AFS Conbined Technique

Mercury is wide distributed in nature and plays an important role inhuman’s producting and living areas. However, it’s one of the mostharmful elements to human and environment. The amount of mercuryexits in environmental samples always very low, but owing to migration,transformation, chemical stability, it would be biomagnified through thefood chain. The toxicity of mercury species is strongly depended on itsform. Usually the orgnic mercury is far more toxic than inorganicmercury, and the most toxic mercury compound is methyl mercury.According to Chinese standards that the total mercury is detected byAtomic Fluorescence Spectrometry and the speciation of mercury isdetected by Gas Chromatography. Unfortunately, no method in Chinesestandard was established to detected the different mercury species at thesame time. Thus, speciation of mercury and detection of total mercurybecame more and more important.In this paper, High Performance Liquid Chromatography or HydrideGeneration combined with Atomic Fluorescence Spectrometry methodwere proposed to detect the total and species mercury in environmentalsample. The main work and conclusions are as follow:An ionic liquid based dispersive liquid-liquid microextractioncombined with HPLC-AFS method for the preconcentration and determination of Hg²⁺, MeHg⁺, EtHg⁺and PhHg⁺in environmental watersample is described. The effect of instrument and preconcentrationconditions to extraction efficiency were compaired. In this thesis, ionicliquid [C8MIM][PF6] was used as the extractant,0.02%acetone-dithizoneas the dispersant-chelatant, and extract for5min. Under the optimizedconditions, the detection limits of the analytes were0.031μg/L for Hg²⁺,0.016μg/L for MeHg⁺,0.024μg/L for EtHg⁺and0.092μg/L for PhHg⁺,respectively. The repeatability of method,expressed as RSD, was between1.4%and5.2%（n=10）, and the average recoveries for spiked test were96.9%for Hg²⁺,90.9%for MeHg⁺,90.5%for EtHg⁺,92.3%for PhHg⁺,respectively. The developed method was successfully applied for thespeciation of mercury in environmental water samples.A ultrasonic extraction, High Performance Liquid Chromatography-Atomic Fluorescence Spectrometry was established for speciationanalysis of Hg²⁺, MeHg⁺, EtHg⁺in seafood. By compairing the extractant,chelatant, extraction time and centrifugation time to achieve the bestexperimental parameters. The mercury compounds were separated byVenusil MP C18column （4.6×150mm） with a mobile of5%CH3CN,0.12%L-cysteine and0.5%CH3COONH4. The samples were extractedby5mol/L HCl and ultrasonic for3.0h. Then adjust pH by NaOH aftercentrifugate and chelate with Na2S2O3. Finally, mercury species in samplewas analysised by HPLC-AFS. The method was applied to detect sevenseafoods, which were bought from WenZhou ChaShan market shows thatMeHg⁺is the main species in seafood, but under the Chinese standard.The linear ranges for Hg²⁺, MeHg⁺, EtHg⁺were between0²0μg/L, withcorrelative coefficients more than0.9990. The detection limits were1.04,1.09,1.29μg/L, respectively，and the relative standard deviations （n=10）for the mercury species were all under5%. The spiked recoveries formercury compounds in Wenzhou seafood were range from90.1%to107.3%. The proposed method of HPLC-AFS is simple, accurate, no interference, and was suitable for the speciation of mercury in seafood,especially for Chinese.Microwave digestion as pre-treatment, followed with HydrideGeneration-Atomic Fluorescence Spectrometry was proposed to detectthe mercury in cosmetics. The method and amount of pre-treatment andinstrument parameter was optimized. The HG-AFS operating conditionwas as follow:negative high boltage,300V;lamp current30Ma;flow ratesof Ar carrier gas and shielding gas,300and800mL/min;Height ofatomizer,8mm;intake volumn,0.7mL;carring agents,5%HCl;reducingagents,0.5%KOH+3%KBH4. Then good linearity ranging was got with acorrelation coefficient of0.9993, RSD=0.77%（n=10）,LOD=0.008μg/L.By compairing microwave digestion, acid extraction and wet digestion, Itwas indicated by investigation results that10mL HNO3+6mL H2O2as theagents for microwave digestion. And0.5g of emuision or cleansing cream,20mL lotion was used for mercury detection.20cosmetics were detectedby the developed method, the mercury in them were all less than Chinesestandard1mg/kg, spiked recoveries were range from90%to105%. Theoutcome was satisfied, and could meet the requirements for the analysisof mercury in cosmetics.