修饰电极伏安法快速测定食品中抗坏血酸和亚硝酸盐

Rapid voltammetric determination of ascorbic acid and nitrite in the food samples at a composite modified electrode

在玻碳电极基底上,采用多步电聚合修饰方法制备了一种含聚谷氨酸和稀土离子杂多核金属氰桥配位聚合物(Cy MCP)的新型复合化学修饰电极(Poly(glutamic acid)/Ho(Ⅲ)-Fe(Ⅲ)-WO2-4Cy M CP/GCE),并用扫描电子显微镜对修饰物的表观形貌进行了表征。电化学实验结果证明:此修饰电极对抗坏血酸(AA)和亚硝酸盐的直接电氧化反应呈现出优异的协同催化活性和抗毒化能力;用示差脉冲伏安法测定AA和NO_2^-的伏安峰形好,相互干扰少;两种测定物的氧化峰电流值(Ip)与其浓度(c)在20~10000μmol/L的范围内均有良好的双对数型线性关系,线性方程分别为lgIp(μA)=-1.425+0.8393lgcAA(μmol/L),R^2=0.9998和lgIp(μA)=-1.475+0.9282lgcNitrite(μmol/L),R^2=0.9992;对AA和NO_2^-的检出限分别为5.8μmol/L和3.9μmol/L(S/N=3)。用本方法对经简单预处理后的实际食品样进行了快速测定,加标回收率均在89.9%~125.6%范围内。

In this study,the composite material made up of poly（glutamic acid） and 3 d-4 f hybridmetallic cyano-bridged coordination polymer（Ho（Ⅲ）-Fe（Ⅲ）-WO2-4-Cy MCP） was successfully decorated onto a glassy carbon electrode using the multi-step electrochemical polymerization method.The surface morphologies of the chemically modified electrode were characterized by scanning electron microscopy（SEM）.All experimental results verified that there were the excellent synergistic catalytic performance and anti-fouling capability for the direct electro-oxidation reaction of ascorbic acid（AA）and nitrite（NO2^-）.In addition,by using differential pulse voltammetry（DPV）,AA and NO2^- were simultaneously detected with the good voltammetric peak profile and less mutual interference.Simultaneously,there was a good linear relationship between the logarithms of their oxidation peak current and concentration in the range from 20 to 10000 μmol/L at the modified electrode,and the linear regression equations were lgIp（μA） =-1.425 ＋ 0.8393 lg cAA（μmol/L）,R^2= 0.9998 and lgIp（μA） =-1.475 ＋ 0.9282 lg cNitrite（μmol/L）,R^2= 0.9992,respectively.The lower detection limits of AA and NO2^- were 5.8 μmol/L and 3.9 μmol/L（S/N = 3）.Therefore,the total content of AA and NO2^- in real food samples which merely underwent a simple pretreatment operation could be selectively and rapidly determined with a recovery of 89.9% ～ 125.6%.