A novel approach is presented to determine hydrophilic phenols in olive oil samples, employing vortex-assisted reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) for sample preparation and screen-printed carbon electrodes for voltammetric analysis. The oxidation of oleuropein, hydroxytyrosol, caffeic acid, ferulic acid and tyrosol was investigated, being caffeic acid and tyrosol selected for quantification. A matrix-matching calibration using sunflower oil as analyte-free sample diluted with hexane was employed to compensate matrix effects. Samples were analyzed under optimized RP-DLLME conditions, i.e., extractant phase, 1 M HCl; extractant volume, 100 µL; extraction time, 2 min; centrifugation time, 10 min; centrifugation speed, 4000 rpm. The working range showed a good linearity between 0.075 and 2.5 mg L⁻¹ (r = 0.998, N = 7) for caffeic acid, and between 0.075 and 3 mg L⁻¹ (r = 0.999, N = 8) for tyrosol. The methodological limit of detection was empirically established at 0.022 mg L⁻¹ for both analytes, which is significantly lower than average contents found in olive oil samples. The repeatability was evaluated at two different spiking levels (i.e., 0.5 mg L⁻¹ and 2 mg L⁻¹) and coefficients of variation ranged from 8% to 11% (n = 5). The applicability of the proposed method was tested in olive oil samples of different quality (i.e., refined olive oil, virgin olive oil and extra virgin olive oil). Relative recoveries varied between 83% and 108% showing negligible matrix effects. Finally, fifteen samples were analyzed by the proposed method and a high correlation with the traditional Folin-Ciocalteu spectrophotometric method was obtained. Thereafter, the concentrations of the fifteen oil samples were employed as input variables in linear discriminant analysis in order to distinguish between olive oils of different quality.

提出了一种新颖的方法来测定橄榄油样品中的亲水性酚，采用涡流辅助反相分散液-液微萃取（RP-DLLME）进行样品制备，并使用丝网印刷碳电极进行伏安法分析。研究了橄榄苦苷，羟基酪醇，咖啡酸，阿魏酸和酪醇的氧化，选择了咖啡酸和酪醇进行定量。使用以葵花籽油为己烷稀释的无分析物样品进行基质匹配校准以补偿基质效应。在优化的RP-DLLME条件下分析样品，即萃取相1 M HCl；萃取剂体积为100 µL；提取时间2分钟；离心时间，10分钟；离心速度，4000 rpm。工作范围在0.075至2.5 mg L之间显示出良好的线性咖啡酸为^-1（r = 0.998，N = 7），酪醇为0.075至3 mg L ^-1（r = 0.999，N = 8）。根据经验，两种分析物的检测方法学极限均为0.022 mg L ^-1，这大大低于橄榄油样品中的平均含量。在两个不同的峰值水平（即0.5 mg L ^-1和2 mg L ^-1），变异系数范围为8％至11％（n = 5）。在不同质量的橄榄油样品（即精制橄榄油，初榨橄榄油和特级初榨橄榄油）中测试了该方法的适用性。相对回收率在83％至108％之间变化，表明基质效应可忽略不计。最后，通过该方法对15个样品进行了分析，并与传统的Folin-Ciocalteu分光光度法建立了高度相关性。此后，在线性判别分析中将15个油样品的浓度用作输入变量，以区分不同质量的橄榄油。