title: [Analysis of total mercury and methylmercury concentrations in four commercially important freshwater fish species obtained from Beijing markets].
abstract: OBJECTIVE
  The present paper makes an attempt to evaluate the risk of mercury exposure to human by analyzing the total mercury and methylmercury concentrations of four commercially important freshwater fish species in Beijing market.
  
  
  METHODS
  Fish samples of common carp, grass carp, bighead carp, and snakehead were purchased from Beijing market. Then their muscle, liver and gills were taken out. The total mercury and methylmercury concentrations were determined using ultrasonic-assisted solvent extraction coupled with inductively coupled plasma-mass spectrometry. Samples were digested with 6mol/L HCl and sonicated for 2 hours. Subsequently, some aliquots were directly diluted for determination of total mercury concentrations; the remained extracts were extracted with CH2 C12 , and then back extracted with H20 for determination of methylmercury concentrations. To evaluate the validity of the method, the standard materials of DORM-2 and DOLT-3 were also measured.
  
  
  RESULTS
  According to the concentrations oof total mercury and methylmercury in the muscles, an order was obtained as: snakehead > bighead carp > grass carp > common carp, which showed that the accumulation of mercury in fish was closely related to food chain. Methylmercury were about 80% of the total mercury, whereas there was a positive relationship between total mercury and methylmercury. The mercury distributions in the bighead carp and snakehead fish showed that the order of mercury concentrations was: muscle > liver > gill, the ratio of methylmercury to total mercury was: muscle > gill > liver. Methylmercury was mainly accumulated in the muscle of fish.
  
  
  CONCLUSIONS
  mercury concentrations of the four fishes in Beijing markets were all below the standard level according to the National Standard of China, therefore, it is safe to human health.
authors.affiliation: Key Lahoratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Chun-ying
authors.initials: CY
authors.lastname: Chen
authors.forename: Bai
authors.initials: B
authors.lastname: Li
authors.forename: Yu-feng
authors.initials: YF
authors.lastname: Li
authors.forename: Jiang-xue
authors.initials: JX
authors.lastname: Wang
authors.forename: Yu-xi
authors.initials: YX
authors.lastname: Gao
authors.forename: Zhi-fang
authors.initials: ZF
authors.lastname: Chai
mesh_terms: D000818:Animals; D002681:China; D005399:Fishes / Q000378:metabolism*; D013058:Mass Spectrometry; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D018570:Risk Assessment
chemical_list: D008767:Methylmercury Compounds; D008628:Mercury