在125 mL分液漏斗中，加入水样50 mL、50%（体积分数）硫酸溶液0.5 mL、50%（体积分数）磷酸溶液0.5 mL、2.0 g·L^-1二苯碳酰二肼（DPCI）显色剂溶液2.0 mL，摇匀，静置5 min，加入5.0 g·L^-1十二烷基硫酸钠溶液2 mL、正丁醇2 mL，摇匀，加入5 mL三氯甲烷，剧烈振摇2 min，形成微乳液，静置分层，使DPCI和六价铬在酸性条件下生成的紫红色络合物可以被萃取到三氯甲烷中。将底层的三氯甲烷相转移到样品比色皿中，利用自搭数字图像比色装置进行数字图像比色分析。该装置采用智能手机采集检测区域照片，通过Color Grab软件获取待测物照片R（红色）、G（绿色）、B（蓝色）值中的G值来对水样中的六价铬进行定量。结果显示：六价铬质量浓度在0.010~0.160 mg·L^-1范围内与三氯甲烷层G值呈线性关系，方法检出限（3s/k）为0.008 mg·L^-1。将该方法用于水样中六价铬的测定，测定值的相对标准偏差（n=10）为1.0%~4.2%，加标回收试验结果为95.0%~97.5%。按此方法分析了加标水样，本方法与国家标准方法得到的结果一致。

50 mL of water sample, 0.5 mL of 50% (volume fraction) sulfuric acid solution, 0.5 mL of 50% (volume fraction) phosphoric acid solution and 2.0 mL of 2.0 g·L^-1 DPCI solution were taken and placed into a 125 mL separating funnel, and the mixture was shaken well. After the solution was kept under steady condition for 5 min, 2 mL of 5.0 g L^-1 sodium dodecyl sulfate solution together with 2 mL of n-butanol was added. After shaking, 5 mL of chloroform was added, and the solution was shaken vigorously for 2 min to form microemulsion. The mixture was kept under steady condition to to have the purple complex formed by DPCI and hexavalent chromium under acidic conditions extracted to the chloroform. The bottom chloroform phase was transferred to the sample cuvette, and a self-built digital imaging colorimetric devicethe was used for digital image colorimetric analysis. A smart phone was selected to collect the photos of the detection area, and G values of the R (red), G (green), and B (blue) values of the analyte picture given by Color Grab software was used to quantify the hexavalent chromium in the water sample. As shown by the results, the linearity range between the mass concentration of hexavalent chromium and the G value of the chloroform layer was found in the range of 0.010-0.160 mg·L^-1, with detection limits (3s/k) of 0.008 mg·L^-1. This method was used for the determination of hexavalent chromium in water samples, and values of RSDs (n=10) were found in the range of 1.0%-4.2%. The spiked recovery test was made, giving recoveries ranged from 95.0%-97.5%. The proposed method was used to analyze the spiked water samples, and consistent results were found for this method and the standard method.