提出了均相液液萃取-数字成像比色法测定水中痕量六价铬的方法。取2.5 mL水样,依次加入0.125 mL十二烷基硫酸钠溶液(20 g·L^-1)、0.3 mL硫酸溶液(0.5 mol·L^-1)和0.125 mL含0.04 mol·L^-1二苯碳酰二肼的丙酮溶液,摇匀,反应5 min。再用60 μL邻苯二甲酸二甲酯和400 μL异丙醇的混合液进行萃取,涡旋,离心,通过智能手机比色装置中的Color Grab软件读取萃取层的绿(G)值。结果显示:六价铬标准曲线的线性范围为4~60 μg·L^-1,检出限(3s/k)为1 μg·L^-1;对实际水样进行加标回收试验,本方法所得六价铬测定值与国家标准方法GB 7467-1987的基本一致,回收率为87.8%~109%,测定值的相对标准偏差(n=6)为2.4%~3.7%。

A method for the determination of trace hexavalent chromium in water by digital image colorimetry after homogeneous liquid-liquid extraction was proposed. 2.5 mL of the water sample was taken, then 0.125 mL of sodium dodecyl sulfate solution (20 g·L^-1), 0.3 mL of sulfuric acid solution (0.5 mol·L^-1) and 0.125 mL of acetone solution containing 0.04 mol·L^-1 diphenylcar-bozide were added in sequence, and shaken well, reacted for 5 min. A mixture of 60 μL of dimethyl phthalate and 400 μL of isopropyl alcohol was used for extraction. After vortex and centrifugation, the green (G) value of the extraction layer was read by the Color Grab software in the color colorimetric device of smart phone. It was shown that linear range of the standard curve of hexavalent chromium was 4-60 μg·L^-1, with detection limit (3s/k) of 1 μg·L^-1. Test for recovery was made on the actual water samples by standard addition method, and the determined values of hexavalent chromium obtained by this method was basically consistent with those of the national standard method GB 7467-1987, with values of the recovery in the range of 87.8%-109%, RSDs (n=6) of the determined values in the range of 2.4%-3.7%.