Study On The Method And Its Application On Speciation Determination Of Arsenic And Mercury In Aquatic Products

The quality safety problem of aquatic product problem has increasingly attracted greatattention of the international community, and the detection of heavy metals in aquaticproducts has become a check item ruled by food safety supervision departments of variouscountries. The toxicity and biological effects of heavy metals depend on their chemicalspeciation, so they cannot fully reflect the degree of harms only by the detection of totalheavy metals amount. Using the arsenic and mercury of typical aquatic products (fish andshrimp) as the research objects, this research on the speciation analysis method of mercuryand arsenic was conducted by high performance liquid chromatography-inductively coupledplasma mass spectrometry (HPLC-ICP-MS) through the optimizations of the samples’pretreatments, the heavy metal’ separation and enrichment, and the instrument parameters’selection, so as to provide technical supports for establishing simple, rapid and effectivespeciation analytical methods of arsenic and mercury in aquatic products. At the same time,the optimized detection methods were used in sampling inspection and survey analysis of thespeciation and pollution status of mercury and arsenic in typical aquatic products inZhongshan city, hoping to provide reference and basis for the safety supervision of aquaticproducts. In this paper, the main results are as follows:1. Optimization of the determination of arsenic speciation in aquatic products: the typesof chromatographic column, the concentrations and pH of mobile phase, the types ofextraction agent, and the methods of assisted–extraction were studied as influencing factorson the extraction rates of arsenic compounds. The column of Hamilton PRP-X100isdetermined as the best one for the complete separation of arsenic compounds byHPLC-ICP-MS within9min.15mmol·L-1NH4H2PO4with pH10.0was used as the mobilephase. The extraction solvent is acetic acid-water (1:19, V/V) and the time ofultrasonic-assisted extraction is26min. Under the optimized conditions, the linear range ofthese four kinds of arsenic compounds is2.5~100g·L-1, and the correlation coefficient ismore than0.995. The detection limit of As(Ⅲ), As(Ⅴ), MMA(V) and AsB are0.3g·L-1,0.7g·L-1,0.6g·L-1and0.8g·L-1respectively. The RSDs (Relative Standard Deviation) of these four kinds of arsenic compounds is less than5%, and the standard addition recoveriesmeet the requirements of the trace analysis for different concentrations of arsenic compounds.2. Optimization of the determination of mercury speciation in aquatic products:discussing the influence of different factors on the extraction rates of mercury compounds,such as the types and concentrations of acid extraction agents, the microwave dissolutiontemperature and time, the mobile phases and so on. Finally the best condition for the detectionof methyl mercury and ethyl mercury in aquatic products by HPLC-ICP-MS is determined:choosing5mol·L-1HCl for sample extraction, microwave dissolution at80C for10min, andadding0.12%(V/V) L-cysteine as the complexants. The linear range of these two kinds ofmercury compounds is0.05~10mg·L-1, and the correlation coefficient is0.9999. Thedetection limits of methyl mercury and ethyl mercury are0.024mg·L-1and0.042mg·L-1respectively. The RSDs of these two kinds of mercury compounds are both less than5%, andthe standard addition recoveries meet the requirements of the trace analysis for differentconcentrations of mercury compounds.3. Based on the optimized methods,160batches of8kinds of aquatic products inZhong-shan City from different market sources were detected for the speciation and contentsof mercury compounds and arsenic compounds. The results showed that the methyl mercurycompounds and inorganic arsenic compounds with high toxicity were not detected in therandom samples. Trace ethyl mercury were found in4batches and arsenobetaine appeared in22batches. The investigation indicates that the levels of mercury and arsenic pollution ofthese regional aquatic products are in safe ranges.