基于溶解度参数的计算检测沉积物中微塑料

Determination of microplastics in sediments based on solubility parameter calculation

目前,密度分离法广泛应用于各种环境介质中微塑料的提取。为了进一步准确测量沉积物中微塑料的质量浓度,本研究开发了一种基于溶解度参数(δ)计算的选择性检测方法,建立了加速溶剂萃取(ASE)-微塑料选择性析出-傅里叶变换红外光谱仪(FTIR)检测的技术路线。6种微塑料[聚丙烯(PP)、聚乙烯(PE)、聚苯乙烯(PS)、聚碳酸酯(PC)、聚氯乙烯(PVC)和聚对苯二甲酸乙二醇酯(PET)]被添加到沉积物中,所得到的提取液分别通过3种方式进行预处理:(a)直接抽滤;(b)浓缩;(c)浓缩后调节溶剂体系溶解度参数。结果表明,微塑料的回收率均随着溶剂体系溶解度参数与微塑料的差值│Δδ│的增大有明显提高。此外,增大│Δδ│值对微塑料的选择性析出可明显去除FTIR检测过程中的干扰。将本方法应用于采集自黄河三角洲地区的30个实际沉积物样品的分析检测,共检出4种微塑料,其赋存特征与已有报道一致。本研究所建立的方法可为复杂环境固体基质中微塑料的精确测量提供技术支持。

Density separation method was widely used as a pretreatment procedure for microplastics analysis in various environmental matrices.To accurately measure the mass concentration of microplastics in sediment,a selective-purification procedure based on solubility parameter(δ)calculation was developed.The technical roadmap of accelerated solvent extraction(ASE)-selective precipitation of microplastics-Fourier Transform infrared spectroscopy(FTIR)analysis was established.Six types of microplastics[polypropylene(PP),polyethylene(PE),polystyrene(PS),polycarbonate(PC),polyvinyl chloride(PVC)and polyethylene terephthalate(PET)]were spiked into sediments for method development.The obtained extract was treated in three different ways:(a)direct filtration;(b)concentration;(c)adjust solubility parameters of the solvent system after concentration.The effect of three kinds of purification treatments was evaluated.The results indicated that the recoveries of microplastics increased obviously with the increase of│Δδ│value between the solubility parameters of the solvent system and the microplastics.Besides,the interference of FTIR analysis could be removed obviously by increasing the│Δδ│value for the selective precipitation of microplastics.The established method was successfully applied to the analysis of 30 sediment samples.Four kinds of microplastics were detected,and their occurrence characteristics were consistent with the previous reports.This work provided technical support to meet the need of accurate measurement of microplastics in complex environment solid matrices.