高等学校化学研究 ›› 2001, Vol. 17 ›› Issue (1): 41-47.
Catalytic Kinetic Determination of Micro Amounts of Oxalic Acid by Second-Order Derivative Oscillopolarography
LI Li-jun1, HONG Zhe2
- 1. Guangxi Institute of Technology, Liuzhou 545005, P. R. China;
2. Chemical Engineering Department, Dandong College, Dandong 118003, P. R. China
Catalytic Kinetic Determination of Micro Amounts of Oxalic Acid by Second-Order Derivative Oscillopolarography
LI Li-jun1, HONG Zhe2
- 1. Guangxi Institute of Technology, Liuzhou 545005, P. R. China;
2. Chemical Engineering Department, Dandong College, Dandong 118003, P. R. China
摘要： It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K2Cr2O7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃. Orange Ⅳ exhibited a sensitive second-order derivative polarographic wave at -0.50 V(vs. SCE). This provides the basis for a sensitive and selective catalytic kinetic method for oxalate determination with second-order derivative oscillopolarography. The effects of sulphuric acid, K2Cr2O7, and orange Ⅳ concentrations, reaction temperature and reaction time were investigated. A calibration curve of oxalate in the range of 0.1—2.0 μg/mL was obtained by the fixed-time procedure. The detection limit was 0.03 μg/ mL. The possible interference from co-existing substances or ions was examined. The new method has a high sensitivity and a good selectivity compared to other existing methods for oxalic acid determination. It has been applied to the determination of micro amounts of oxalate in real urine samples with satisfactory results.