材料期刊网

以氯仿为萃取剂,甲醇为分散剂,铜试剂(二乙基二硫代氨基甲酸钠)为鳌合剂,建立了分散液相微萃取-分光光度法测定水中痕量铜的新方法。于50 mL离心试管中加入一定量的Cu2+标准溶液、50μL 1．0 g/L铜试剂溶液,加水稀释至近50 mL,用1 mol/L盐酸调节pH值为3．0,定容。然后将3．25 mL由氯仿与无水甲醇组成的体积比为3∶10的混合液快速打入该离心管中,使之混合形成均匀浊相,萃取4 min后在3000 r/min的条件下离心分离2 min,再抽取下层萃取液置于光程为1 cm的微型石英比色皿中。以空白试剂为参比,在波长为440 nm处测定其吸光度,结果表明,铜质量浓度在0．5~10μg/L范围内与其对应的吸光度呈良好的线性关系,相关系数(r)为0．9939,方法检出限为0．069μg/L。将实验方法应用于水样中痕量铜的测定,测得结果与火焰原子吸收光谱法(FAAS)基本一致,相对标准偏差(RSD,n=5)为3．1%~4．0%。

A new determination method of trace copper in water by dispersive liquid phase microextraction combined with spectrophotometry was established with chloroform as extraction agent, methanol as dispersant and copper rea-gent (sodium diethyldithiocarbamate) as chelating agent. Certain amount of Cu2+standard solution and 50μL of 1. 0 g/L copper reagent solution were added into 50 mL centrifuge tube. After dilution with water to about 50 mL, the pH of solution was adjusted to 3. 0 with 1 mol/L hydrochloric acid. Then, the solution was diluted to the mark. Af-ter that, 3. 25 mL of mixture composed by chloroform and methanol with volume ratio of 3 ∶ 10 was rapidly added into the centrifuge tube above to form uniformly turbid phase. After extraction for 4 min, the solution was centrifu-gally separated at 3 000 r/min for 2 min. The extract at lower layer was sampled into 1 cm micro quartz colorimetric utensil. The absorbance was measured at 440 nm with blank reagent as reference. The results showed that the mass concentration of copper in range of 0. 5-10 μg/L had good linear relationship with its corresponding absorbance. The correlation coefficient was 0. 993 9. The detection limit of method was 0. 069 μg/L. The proposed method was applied to the determination of trace copper in water sample, and the results were basically consistent with those ob-tained by flame atomic absorption spectrometry (FAAS). The relative standard deviations (RSD, n=5) were be-tween 3 . 1% and 4 . 0%.