为获得不同pH值对测定六价铬（Cr(Ⅵ)）的影响，以标准分析方法二苯碳酰二肼(C₁₃H₁₄N₄O)分光光度法为基础，选用2种体积浓度的水样，分别加入不同的酸量，测定吸光度。经EXCEL软件对实测数据分析，得出加酸量与吸光度具有紧密的相关性，发现吸光度随着溶液pH值的减小而减小，酸度偏大，测定的实际结果比真实值小， pH值的不同对Cr(Ⅵ)测定结果具有影响。采用灰色系统模型GM（1，1）对实验数据进行处理，推导出不同酸度下的吸光度直线方程式。经t检验和F检验证明，计算出的吸光度值与测定值不存在显著性差异，可帮助定量掌握不同酸度条件下对测定Cr(Ⅵ)产生影响具有一定的作用。

Based on the 1,5-diphenylcarbazide spectrophotometry, we researched on the influence of pH value on the determination of hexavalent chromium. By adding different amounts of acid into two water samples with different volumes and concentrations, we measured the absorbances of the solutions so as to determine the hexavalent chromium. Through analysis by EXCEL on the measured data, we found that the absorbance reduced with the decrease of pH value. In the presence of high acidity, which means small pH value, the measured hexavalent chromium was smaller than the original value before adding acid. Therefore, the variation of pH value had an impact on the measurement of hexavalent chromium. Moreover, we employed the gray system model GM(1,1) to process the experimental data, and derived a linear equation for the absorbance under different acidities. Through t  test and  F  test, no significant difference was found between calculated absorbance and measured absorbance. This research is helpful to quantitatively looking into the influence of pH value on hexavalent chromium determination.