微萃取原子吸收法检测水中微量铬

采用分散液液微萃取分离技术结合火焰原子吸收法,提出了一种新的环境水样中痕量铬的检测方法。用吡咯烷二硫代氨基甲酸铵做螯合剂,四氯化碳做萃取剂,乙醇做分散剂。选定并优化了萃取的影响参数。这些参数包括萃取剂和分散剂的类型以及它们的体积、萃取时间、酸碱度和螯合剂的用量等等。通过条件优化,Cr（Ⅵ）和总铬富集率分别达到270和259。校准曲线在1～50μg·L^-1的浓度范围内呈线性,Cr（Ⅵ）和总铬的检出限分别为0.12和0.15μg·L^-1,相对标准偏差分别为2.1%和2.7%。（N=5）该法简便快速,用于自来水、井水和河水中铬的形态分析,结果较满意。

Determination of trace chromium by combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry

The dispersive liquid-liquid microextraction（DLLME） was combined with the flame atomic absorption spectrometry（FAAS） for determination of chromium in the water samples.Ammonium pyrrolidine dithiocarbamate（APDC）,carbon tetrachloride and ethanol were used as chelating agent,extraction solvent and disperser solvent respectively.Effects influencing complex formation and extraction（such as pH,temperature,time,solvent and the amount of chelating agent） have been optimized.Enrichment factors up to 270 and 259 were obtained for Cr（VI） and total Cr,respectively.The calibration graph is linear from 1 to 50μg·L^-1,and detection limits are 0.12 and 0.15μg·L^-1 for Cr（VI） and total Cr,respectively.Relative standard deviations（RSD） were obtained to be 2.1% for Cr（VI） and 2.7% for total Cr（n=5）.