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目的:建立碳糊电极(CPE)吸附催化伏安法测定大黄酸的方法。方法:在0.30mol.L-1NH3.H2O-NH4Cl(pH8.2)缓冲溶液中,0V(vs.SCE)富集60s,以250mV.s-1扫速线性扫描至-1.0V。大黄酸在CPE上于-0.67V处产生一灵敏的吸附催化伏安峰。结果:其二阶导数峰电流与大黄酸的浓度在4.0×10-11～2.0×10-9mol.L-1(富集60s)和2.0×10-9～4.0×10-8mol.L-1(富集30s)范围内成良好的线性关系,相关系数分别为0.9990和0.9989,检出限为2.0×10-11mol.L-1。初步探讨了大黄酸在CPE和汞电极上的伏安行为和电极反应机理,并用于中药大黄中的大黄酸的测定,结果满意。结论:电极制作简便,线性范围宽,方法灵敏度高。
Objective: To establish a method for the determination of rhein by catalytic voltammetry with carbon paste electrode (CPE) adsorption. Methods: In 0.30mol.L-1NH3.H2O-NH4Cl (pH8.2) buffer solution, 0V (vs.SCE) was enriched for 60s and linearly swept to -1.0V at 250mV.s-1. Rhein produced a sensitive, adsorptive voltammetric peak at -0.67 V at CPE. Results: The second derivative peak current and the concentration of rhein were in the range of 4.0 × 10-11 ~ 2.0 × 10-9 mol·L-1 (60s) and 2.0 × 10-9 ~ 4.0 × 10-8 mol·L-1 (Enrichment 30s) within a good linear relationship, the correlation coefficients were 0.9990 and 0.9989, the detection limit of 2.0 × 10-11mol.L-1. The voltammetric behavior and electrode reaction mechanism of rhein at CPE and mercury electrode were preliminarily discussed. The rhein was also used in the determination of rhein in Chinese rhubarb. The results were satisfactory. Conclusion: The electrode has the advantages of simple manufacture, wide linear range and high sensitivity.