次甲基蓝-重铬酸钾体系测定草酸浓度的研究  

Determination of Oxalic Acid with Methylene Blue-Dichromate System

作　　者：梁磊[1] 谭贺[1] 金朝霞[1] 李宪臻[1] 

机构地区：[1]大连轻工业学院生物与食品工程系,辽宁大连116034

出　　处：《分析测试学报》2006年第1期98-101,共4页Journal of Instrumental Analysis

摘　　要：在酸性介质中草酸能够催化重铬酸钾对次甲基蓝的氧化脱色反应，这种催化效率与草酸浓度呈正相关，据此建立了次甲基蓝-重铬酸钾体系测定草酸的方法。实验证明，在660nm处不加草酸与加草酸的次甲基蓝-重铬酸钾体系反应后的吸光度差值△A在0～80μg／mL范围内与草酸浓度呈线性关系，线性方程为：△A=0．0984P草酸-0．0043，相关系数为0．9986。反应的最适条件为3．752×10^-5mol／L次甲基蓝、0．12mol／LH2SO4和2×10^-3mol／L K2Cr2O7。A method for the determination of oxalic acid with methylene blue - dichromate system has been developed. It is based on the catalytic effect of oxalic acid on the oxidation of methylene blue by dichromate in acidic media. The absorbance of methylene blue at the maximum wavelength of 660 nm was recorded at fixed reaction times. The absorbance differences （△A） of the methylene blue -dichromate system with and without oxalic acid were linearly correlated with the oxalic acid concentration. The linear range of the calibration graph for oxalic acid was 0 - 80μg/mL with a correlation coefficient of 0. 998 6. The optimum concentrations for methylene blue, H2SO4 and K2Cr2O7 were 3.752×10^-5 mol/L, 0. 12 mol/L and 2 mmol/L, respectively. The developed method is simple, sensitive and inexpensive.

关 键 词：草酸 次甲基蓝 重铬酸钾 分光光度法 

分 类 号：O657.32[理学—分析化学]