Abstract: TWO NEW NEUTRON ACTIVATION TECHNIQUES FOR SIMULTANEOUS DETERMINATION OF METHYLMERCURY AND INORGANIC MERCURY IN HUMAN HAIRFeng Weiyue;Qian Qinfang;Chai Zhifang;Zang Peiqun;Lu xiangli（Institute of High Energy Physics,Laboratory of Nuclear Analysis Techniques,the Chinese Academy of Sciences,P.O.Box 2732,Beijing 100080)Abstract:Two neutron activation analysis（NAA）methods for simultaneous determination of n1ethylmercury（MeHg）and inorganic mercury in human hair have been developed．One is based on the volatility of methylmercury cyanide,The sample is mixed with potassium hexacyanoferrate and sulphuric acid, forming methylmercury cyanide,Then the methylmercury cyanide is absorbed by cysteine paper, Finally,the cysteine paper is irradiated and measured by instrumental neutron activation analysis（INAA）．Another method is based on the hydrochloric acid extraction of methylmercury.The residue phase containing inorganic mercury can be detern1ined by NAA.Further,the MeHg contents in samples are able to be easily calculated by subtracting the inorganic mercury contribution from the total mercury given by INAA.The aqueous phase can be collected and directly determined for the methylmercury or the organic mercury by gas chromatography with electron capture（GC-EC）,cold vapor atomic absorption spectrometry（CV-AAS）,etc.The accuracy for inorganic and methylmercurv determination has been examined by many biological standard reference materials analyses and by interlaboratory comparisons.All the results are in good agreement with the certified values and those obtained by the reference laboratory（Jozef Stefan Institute,Ljubljana,Slovenija）.Keywords:Biological samples Inorganic mercury MethyIn1ercury Neutron activation analysis