Gamella M, Campuzano S, Reviejo A J, Pingarrón J M
Department of Analytical Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
J Agric Food Chem. 2006 Oct 18;54(21):7960-7. doi: 10.1021/jf061451r.
The use of a laccase biosensor, under both batch and flow injection (FI) conditions, for a rapid and reliable amperometric estimation of the total content of polyphenolic compounds in wines is reported. The enzyme was immobilized by cross-linking with glutaraldehyde onto a glassy carbon electrode. Caffeic acid and gallic acid were selected as standard compounds to carry out such estimation. Experimental variables such as the enzyme loading, the applied potential, and the pH value were optimized, and different aspects regarding the operational stability of the laccase biosensor were evaluated. Using batch amperometry at -200 mV, the detection limits obtained were 2.6 x 10(-3) and 7.2 x 10(-4) mg L(-1) gallic acid and caffeic acid, respectively, which compares advantageously with previous biosensor designs. An extremely simple sample treatment consisting only of an appropriate dilution of wine sample with the supporting electrolyte solution (0.1 mol L(-1) citrate buffer of pH 5.0) was needed for the amperometric analysis of red, rosé, and white wines. Good correlations were found when the polyphenol indices obtained with the biosensor (in both the batch and FI modes) for different wine samples were plotted versus the results achieved with the classic Folin-Ciocalteu method. Application of the calibration transfer chemometric model (multiplicative fitting) allowed that the confidence intervals (for a significance level of 0.05) for the slope and intercept values of the amperometric index versus Folin-Ciocalteu index plots (r = 0.997) included the unit and zero values, respectively. This indicates that the laccase biosensor can be successfully used for the estimation of the polyphenol index in wines when compared with the Folin-Ciocalteu reference method.
本文报道了一种漆酶生物传感器在分批和流动注射（FI）条件下，用于快速可靠地安培法测定葡萄酒中多酚类化合物总含量的应用。该酶通过与戊二醛交联固定在玻碳电极上。选择咖啡酸和没食子酸作为标准化合物进行此类测定。对酶负载量、施加电位和pH值等实验变量进行了优化，并评估了漆酶生物传感器操作稳定性的不同方面。在-200 mV下使用分批安培法，没食子酸和咖啡酸的检测限分别为2.6×10⁻³和7.2×10⁻⁴mg L⁻¹，与先前的生物传感器设计相比具有优势。对红葡萄酒、桃红葡萄酒和白葡萄酒进行安培分析时，仅需将葡萄酒样品用支持电解质溶液（pH 5.0的0.1 mol L⁻¹柠檬酸盐缓冲液）进行适当稀释这种极其简单的样品处理。当将生物传感器（分批和FI模式）获得的不同葡萄酒样品的多酚指数与经典Folin-Ciocalteu方法获得的结果作图时，发现具有良好的相关性。应用校准转移化学计量模型（乘法拟合）使得安培指数与Folin-Ciocalteu指数图（r = 0.997）的斜率和截距值的置信区间（显著性水平为0.05）分别包含单位值和零值。这表明与Folin-Ciocalteu参考方法相比，漆酶生物传感器可成功用于葡萄酒中多酚指数的测定。
