十六烷基三甲基溴化铵对石墨烯电极在多巴胺共存时测定抗坏血酸的研究

制备了石墨烯碳糊电极,利用十六烷基三甲基溴化铵作为区分试剂考察了抗坏血酸在此电极上的电化学行为,讨论了电极制备条件、十六烷基三甲基溴化铵的用量及多巴胺的存在对抗坏血酸电化学行为的影响。结果表明,在pH=6.5的磷酸盐缓冲溶液中,并于1.0×10-5mol/L多巴胺存在下,抗坏血酸氧化峰电流与其浓度在2×10-5~5×10-4mol/L范围呈线性关系,最低检出限为8×10-6mol/L。并用塔菲尔法测定了抗坏血酸电极过程的动力学参数,其电荷传递系数β=0.443,标准速率常数k0=（3.73±0.10）×10-5cm/s。电位阶跃法测得抗坏血酸的扩散系数D=4.86×10-5cm2/s。此电极有良好的重复性和稳定性。应用此方法分析了含多巴胺的抗坏血酸的混合溶液,测定结果的相对标准偏差R=1.24%,回收率在100.74%～102.34%之间。

Effects of cetyltrimethyl ammonium bromide on graphene electrode for determination of ascorbic acid in the presence of dopamine

This paper presents the preparation of the graphene paste electrode,the effects of cetyltrimethyl ammonium bromide on the electrochemical behaviors of ascorbic acid and determination of ascorbic acid in the present of dopamine.The results showed that the peak currents depended linearly on the concentration of ascorbic acid from 0.02 to 0.50 mmol/L with R=0.998 7(n=8) in the phosphate buffer solution of pH=6.5 including 1.0×10-5 mol/L dopamine.The detection limit was(8.6±0.001) μmol/L.The electron transfer coefficient β was evaluated to be 0.443,the standard rate constant k0 was estimated to be(3.73±0.10)×10-5 cm/s.The diffusion coefficient for ascorbic acid was found to be 4.86×10-5 cm2/s.This electrode had excellent reproducibility and stability.The determination for the real tablets yielded a good mean recovery of 100.74%～102.34% with a relative standard deviation of 1.24%.