基于表面活性剂存在下电化学结合化学计量学同时测定3种着色剂

Simultaneous differential pulse stripping voltammetric determination of three food colorants in presence of CTAB with aid of chemometrics

利用微分脉冲伏安法研究了日落黄、苋菜红和柠檬黄等3种着色剂在裸玻碳电极上的电化学行为及定量分析测定的可行性。实验发现,在表面活性剂溴化十六烷基三甲铵(CTAB,浓度为40.0×10-6 mol.L-1)存在下,3种着色剂日落黄、苋菜红和柠檬黄均具有较高的电化学测定灵敏度,它们的线性范围分别为4.0～40.0,5.0～60.0和2.5～35.0nmol.L-1,对应的最低检测线分别为1.54,2.38和1.10nmol.L-1。但这3种被测物质中日落黄和苋菜红的伏安波谱相互重叠,因此在不进行化学分离预处理的情况下很难对这3种着色剂同时进行测定。采用偏最小二乘法、主成分分析以及它们的一阶导数等化学计量学方法对它们的重叠伏安谱图进行解析和定量分析,结果表明,导数偏最小二乘法的计算结果最好,总相对预测误差(RPET)为6.18%。利用提出的方法对冰激凌、汽水和糖果等实际样中的3种着色剂进行直接测定,获得了较好的定量分析结果。

The differential pulse stripping voltammetric （DPSV） method was developed, to determine hree colorants,sunset yellow,amaranth and tartrazine. The method proposed was based on the adsorptive accumulation of the colorants on the carbon electrode, and the oxidation of the absorptive species by the voltammetry. The 40.0×10^-6 mol.L^-1 of cetyltrimethyl ammonium bromide （CTAB） was used as the optimal for the experiment. The linear concentration ranges were found to be 4.0-40.0,5.0-60. 0 and 2. 5-35. O nmol. L^-1, for sunset yellow, amaranth and tartrazine, respectively. Their corresponding detection limits were 1.54,2.38 and 1.10 nmol.L-^-1. Since the voltammograms of these colorants were seriously overlapped,it was difficult to determine them individually from the voltammetric signals of the mixtures. Thus, some chemometrics methods,such as partial least squares （PLS）,principle component regression （PCR） and their first-order derivative methods （DPLS and DPCR）, were applied to quantitatively resolve the overlapping signals in this paper. We found that the DPLS gave the best results with total relative prediction er- ror （RPET） of 6.18 %. The method was applied to determine three colorants in several commercial food samples, like soft drink, ice cream and candy samples, and yielded satisfactory recoveries.