以酸性铬蓝K-萘酚绿B为显色剂测定钙镁离子浓度的方法

Determination of the Concentration of Calcium and Magnesium Ions with Acid Chrome Blue K(ACKB)-Naphthol Green B as Chromogenic Agent

陈彦广 王海英 柳艳修 宋 华

CHEN Yan-Guang WANG Hai-Ying LIU Yan-Xiu SONG Hua

本文研究了以酸性铬蓝K（ACBK）和萘酚绿B（NGB）的混合指示剂K-B为显色剂，利用722紫外可见分光光度计测定部分水解聚丙烯酰胺溶液中Ca2+、Mg2+总浓度的方法，确定了最佳的测定条件。结果表明，在波长为472 nm下测定吸光度，ACBK与NGB的质量比为1:2，加入含Ca2+、Mg2+ 的混合盐溶液、K-B混合显色剂、pH=10的NH3-NH4Cl缓冲溶液体积比依次为1:3:8，Ca2+、Mg2+总浓度为0~32 mg/L时，绘制的标准曲线服从朗伯-比尔定律，浓度与吸光度的线性拟合方程为A=0.30124+0.01001cm，测定结果平均误差不大于±0.9%。

To determine the concentration of calcium and magnesium ions in polymer solution, the acid chrome blue K(ACBK) -naphthol green B(NGB) mixed indicator K-B was used as chromogenic reagent. In partially hydrolyzed polyacrylamide (HPAM) solution, the influencing factors on the concentration of calcium and magnesium ions were investigated by using 722 UV-Vis spectrophotometer. The results showed that the optimal measurement condition was as follows, the wavelength was 472 nm, the mass ratio of the ACBK to NGB was 1:2, the volume ratio among the mixed solution containing both Ca2+ and Mg2+, indicator K-B solution and NH3-NH4Cl buffer solution with pH value of 10 was 1:3:8, the total concentration of Ca2+ and Mg2+ was in the range of 0 to 32 mg/L. The obtained standard curve obeyed the Lambert-Beer law, and the linear regression equation between concentration and absorbance, A=0.30124+0.01001cm, was obtained, whose average error was less than ±0.9%.