以轻质溶剂辛醇为萃取剂, 建立了分散液液微萃取-石墨炉原子吸收光谱分析法(LDS-DLLME-GFAAS), 并应用于生活用水中痕量Pb及Cd的测定。 在分散液液微萃取(DLLME)中, 以二乙基二硫代氨基甲酸盐(DDTC)为螯合剂, 用微量注射器将辛醇和甲醇的混合溶液快速注入到样品溶液中发生雾化分散现象, Pb2+和Cd2+与DDTC的络合物被萃取到辛醇微滴中。 离心分离后, 以GFAAS测定萃取至上层辛醇相中的分析物。 实验考察了萃取剂种类和体积、 分散剂种类和体积、 pH、 DDTC浓度、 萃取时间等影响萃取效率的实验参数。 在最优实验条件下, Pb和Cd的检出限分别为0.15和0.03 μg·L-1, 富集倍数分别为87和48, 具有良好的线性和精密度。 该分析方法优势在于操作简便, 快速, 低成本, 高富集倍数, 萃取剂用量少, 已成功应用于自来水、 饮用水和南湖水中痕量Pb和Cd的检测。

A simple and efficient method for the determination of Pb and Cd in domestic water and drinking water was developed by combining low-density solvent based dispersive liquid liquid microextraction (LDS-DLLME) with graphite furnace atomic absorption spectrometry (GFAAS). In the LDS-DLLME, a mixed solution of octanol (extraction solvent) and methanol (dispersive solvent) was rapidly injected into the sample solution by a microsyringe to form a cloudy emulsion. With diethyldithiocarbamate (DDTC) as chelating agent, Pb2+ and Cd2+ were extracted into the highly dispersed octanol microdroplets. The mixture was then centrifuged and the chelates of Pb and Cd moving into the organic phase, which was analyzed by GFAAS subsequently. In addition, the experimental conditions were investigated and optimized, such as the type and volume of extractant and dispersant, pH, DDTC concentration and extraction time. Under the optimal experimental conditions, the detection limits of Pb and Cd were 0.15 and 0.03 μg·L-1, and enrichment factors were 87 and 48, respectively, with good linearity and precision. This method has the advantages of simplicity, rapidity, low cost, and high enrichment. It is successfully applied to the determination of trace Pb and Cd in tap water, drinking water and South Lake water.