This work presents the association of cloud point extraction (CPE) and electroanalysis for the selective and sensitive determination of methyl parathion (MP) in honey. The CPE step provided the pre-concentration of MP from a complex sample, in which the optimized extraction parameters (Triton X-100 concentration of 0.75% w/v, NaCl concentration of 1.0% w/v and heating time of 30 min) were investigated using a factorial design (2³). The detection of MP was performed using a cathodically pre-treated boron-doped diamond (BDD) working electrode and square wave voltammetry (SWV), after a suitable dilution of the CPE extract in Britton–Robinson buffer pH 6.0 as the supporting electrolyte. MP presented three electrochemical processes over the BDD surface, but only the reduction peak at around −0.7 V was monitored for the MP determination (higher detectability). Improved reproducibility was reached by applying an in situ cleaning step (+2.0 V for 15 s) followed by a re-activation process (−2.0 V for 15 s) between measurements. Using the optimized variables, a linear range between 0.1 and 2.0 μmol L⁻¹ was obtained for MP with a limit of detection of 0.006 μmol L⁻¹, a 6-fold lower value when compared with the value attained without the CPE step. The experimental enrichment factor of MP was 6.1. Also, the optimized CPE allowed the determination of MP in honey samples with good accuracy (recovery between 94 and 106%), which was not possible using direct detection (without CPE) due to the matrix interference. This is the first paper that demonstrates the combination of CPE and electroanalysis for the determination of an organic compound.

中文翻译：

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与伏安法相关的浊点萃取：预浓缩和消除样品基质，用于痕量测定蜂蜜中的甲基对硫磷

这项工作提出了浊点提取（CPE）和电分析的关联，用于选择性和灵敏地测定蜂蜜中的甲基对硫磷（MP）。CPE步骤提供了对复杂样品中MP的预浓缩，其中优化的提取参数（Triton X-100浓度为0.75％w / v，NaCl浓度为1.0％w / v，加热时间为30分钟）为使用析因设计进行了调查（2 ³）。使用阴极预处理的硼掺杂金刚石（BDD）工作电极和方波伏安法（SWV）进行MP的检测，然后在Britton-Robinson缓冲液pH 6.0中适当稀释CPE提取物作为支持电解质。MP在BDD表面上呈现了三个电化学过程，但仅对-0.7 V左右的还原峰进行了MP测定（更高的可检测性）。通过在测量之间应用原位清洁步骤（+2.0 V，持续15 s），然后进行重新激活过程（-2.0 V，持续15 s），可以实现更高的重现性。使用优化的变量，MP的线性范围介于0.1和2.0μmolL ^-1之间，检出限为0.006μmolL ^-1与没有CPE步骤获得的值相比，该值低6倍。MP的实验富集系数为6.1。而且，优化的CPE可以高精度测定蜂蜜样品中的MP（回收率在94％至106％之间），由于基质干扰，使用直接检测（无CPE）无法实现。这是第一篇证明CPE与电分析相结合测定有机化合物的论文。