Solvent extraction of PM_2.5 samples collected on the filter is a preliminary step for assessing the PM_2.5 oxidative potential (OP) using cell-free assays, as the dithiothreitol (DTT) and the ascorbic acid (AA) assays. In this study, we evaluated the effect of the solvent choice by extracting ambient PM_2.5 samples with different solvents: methanol, as organic solvent, and two aqueous buffers, i.e., phosphate buffer (PB) and Gamble’s solution (G), as a lung fluid surrogate solution. Both the measured volume-based OP_V^DTT and OP_V^AA responses varied for the different extraction methods, since methanol extraction generated the lowest values and phosphate buffer the highest. Although all the tested solvents produced intercorrelated OP_V^DTT values, the phosphate buffer resulted the most useful for OP^DTT assessment, as it provided the most sensible measure (nearly double values) compared with other extractions. The association of the measured OP_V values with PM chemical composition suggested that oxidative properties of the investigated PM_2.5 samples depend on both transition metals and quinones, as also supported by additional experimental measurements on standard solutions of redox-active species.

对过滤器上收集的 PM _2.5样品进行溶剂萃取是使用无细胞检测评估 PM _2.5氧化潜力 (OP)的初步步骤，如二硫苏糖醇 (DTT) 和抗坏血酸 (AA) 检测。在本研究中，我们通过使用不同溶剂提取环境 PM _2.5样品来评估溶剂选择的影响：甲醇作为有机溶剂，以及两种水性缓冲液，即磷酸盐缓冲液 (PB) 和 Gamble 溶液 (G)，作为肺流体替代溶液。基于测量体积的 OP _V ^DTT和 OP _V ^AA不同提取方法的反应各不相同，因为甲醇提取产生的值最低，磷酸盐缓冲液的值最高。尽管所有测试的溶剂都产生了相互关联的 OP _V ^DTT值，但磷酸盐缓冲液对 OP ^DTT评估最有用，因为与其他提取物相比，它提供了最明智的测量（接近两倍的值）。测得的 OP _V值与 PM 化学成分的关联表明，所研究的 PM _2.5样品的氧化特性取决于过渡金属和醌，这也得到了对氧化还原活性物质标准溶液的额外实验测量的支持。