Institute of Food Chemistry, University of Hohenheim, Garbenstraße 28, 70599 Stuttgart, Germany.
Nestlé Research Center, Route du Jorat 57, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
J Chromatogr A. 2019 Nov 22;1606:460380. doi: 10.1016/j.chroma.2019.460380. Epub 2019 Jul 25.
Extraction of chlorinated paraffins (CPs) in samples with high fat content is generally performed by a sulfuric acid treatment and liquid-liquid partitioning in n-hexane, followed by clean-up by column chromatography. Analysis and quantitation are commonly carried out via gas chromatography coupled with electron capture negative ionization mass spectrometry (GC/ECNI-MS) when low- and high-resolution MS (LRMS and HRMS) are used. In this work, we present a completely different and innovative approach for the determination of CPs by applying the planar solid phase extraction (pSPE) concept for a rapid and selective screening. pSPE offers the concentration of the analytes in a single target zone followed by the densitometric determination of the total CP content. After sulfuric acid treatment and liquid-liquid partition into n-hexane, pSPE was performed on silica gel plates employing a twofold development with cyclohexane/toluene (94:6, v/v) and methylene chloride/n-hexane (9:1, v/v) as mobile phases. CPs were quantified via the visual (VIS) absorption of the target zone after derivatization with o-tolidine, and amounts were calculated as the sum by means of a reference CP. Limits of detection and quantitation for the reference CP were 0.2 and 0.7 mg/kg oil, respectively, and recoveries from different vegetable oils were near 100%. The analysis of total CPs in dietary supplement samples by pSPE-VIS compared to GC/ECNI-HRMS proved the method as a reliable and suitable screening tool providing an appropriate alternative to existing time-consuming and complex methods.
提取高脂肪含量样品中的氯化石蜡（CPs）通常采用硫酸处理和正己烷液液分配，然后通过柱层析进行净化。当使用低分辨和高分辨质谱（LRMS 和 HRMS）时，通常通过气相色谱与电子捕获负电离质谱（GC/ECNI-MS）进行分析和定量。在这项工作中，我们提出了一种完全不同的创新方法，通过应用平面固相萃取（pSPE）概念进行快速选择性筛选来测定 CPs。pSPE 可将分析物浓缩在单个目标区域，然后通过密度计测定总 CP 含量。经过硫酸处理和正己烷液液分配后，采用环己烷/甲苯（94:6，v/v）和二氯甲烷/正己烷（9:1，v/v）作为流动相在硅胶板上进行 pSPE。CPs 通过与邻甲苯胺衍生后的目标区域的可见（VIS）吸收进行定量，并通过参考 CP 以总和的形式计算。参考 CP 的检出限和定量限分别为 0.2 和 0.7mg/kg 油，不同植物油的回收率接近 100%。通过 pSPE-VIS 对膳食补充剂样品中总 CPs 的分析与 GC/ECNI-HRMS 相比，证明该方法是一种可靠且适用的筛选工具，为现有的耗时复杂方法提供了合适的替代方法。
