萃取-石墨炉原子吸收光谱法测定痕量铬及其价态

DETERMINATION OF TRACE CHROMIUM AND VALENCY STATES OF CHROMIUM BY EXTRACTION AND GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

研究了APDC-MIBK(吡咯啶二硫代甲酸铵-甲基异丁基酮)萃取体系石墨炉原子吸收光谱法测定铬及其价态的各种实验条件.采用调节pH值,在不同温度条件下使Cr(Ⅵ)与Cr(Ⅲ+Ⅵ)分别络合萃取的方法进行不同价态及总量的测定.用该法测定了地表水、人发及血清样品中铬的价态及总量,进行了方法考验,10次以上测定的变异系数及回收率分别为:7.51％,1.54％,3.51％和96％～106％,93％～100％,91％～109％.方法的线性范围为0～40μg/L,特征含量0.11ng(进样量为10μL).

A method for the determination of Cr(Ⅲ) and Cr(Ⅳ) in the ppb range by GFAAS is presented. Possible interferences from 34 cations and anions are tried and it is shown that their quantities below certain limits do not affect the analyses of Cr(Ⅲ) or Cr(Ⅳ). This method has been successfully tested with surface water, hair and serum. The calibration graphs are linear in the range of 1 to 40μg/L for Cr. Sensitivity is 0.11ppb of Cr per 1% absorption and the relative standard deviation of 10 determinations for samples at ppb magnitude is less than 8%, whereas the recovery is 91%~109%.