滤膜冷凝收集-离子色谱法测定固液气溶胶中5种水溶性阴离子北大核心CSCD

水溶性离子是固、液气溶胶的重要组成部分,对于气溶胶的理化性质和空气质量具有重大影响,研究水溶性离子的含量对于大气环境的污染与防治具有深远意义。该研究建立了一种滤膜冷凝收集-离子色谱技术采集固体气溶胶和液体气溶胶并测定其中的5种水溶性阴离子(Cl^(-)、F^(-)、NO^(-)_(3)、NO2^(-)、SO4^(2-))含量的方法。首先,采用固体颗粒过滤器和冷凝收集法分别收集固体气溶胶和液体气溶胶,固体气溶胶以固体颗粒物的形式被收集在固体颗粒过滤器内,液体气溶胶以冷凝液的形式在冷阱中被收集。其次,以离子色谱法对固、液体气溶胶中的水溶性阴离子含量进行检测。在以Dionex IonPac AS11-HC-4μm作为分析柱,流速为1 mL/min,柱温为30℃,淋洗液氢氧化钾(KOH)浓度在0~40 min内由1 mol/L线性增至25 mol/L,进样量100μL的条件下,各离子在40 min内有效分离,5种阴离子在0.1~10 mg/L范围内线性关系良好(相关系数为0.9992~0.9997),检出限低(0.02~0.04 mg/L)。对样品采集条件(采样时间、采样温度和采样流量)进行了优化,结果表明,在采样时间2 h、采样温度-13℃、采样流量1.0 L/min的条件下,可获得较为满意的结果。在优化的条件下分别对实际样品的两类溶胶中的5种阴离子含量进行了检测,测得实际样品的液体气溶胶中5种阴离子含量分别为5.7402μg/m^(3)(F^(-))、1.1599μg/m^(3)(Cl^(-))、3.3233μg/m^(3)(NO^(-)_(2))、2.4861μg/m^(3)(NO^(-)_(3))和0.9745μg/m^(3)(SO^(2-)_(4)),固体气溶胶中5种阴离子含量分别为14.1037μg/m^(3)(F^(-))、5.0398μg/m^(3)(Cl^(-))、9.3052μg/m^(3)(NO^(-)_(2))、8.4528μg/m^(3)(NO^(-)_(3))和5.6314μg/m^(3)(SO^(2-)_(4))。该方法可应用于实际的大气检测中,也为其他离子的采集和分析条件的摸索提供了方法。

Determination of five water-soluble anions in solid and liquid aerosols by ion chromatography with a filter membrane and condensation collection

Water-soluble ions are important components of solid and liquid aerosols.The ions have a significant impact on the physical and chemical properties of the aerosols and air quality.Thus,determining the concentrations of water-soluble ions in solid and liquid aerosols has far-reaching significance for mitigating pollution and protecting the atmospheric environment.In this study,a technology combining membrane filtration,condensation,and ion chromatography has been established to collect solid aerosols and liquid aerosols and to measure the amount of five water-soluble anions(Cl^-,F^-,NO^-₃,NO^-₂,and SO^2-₄)in these aerosols.First,a solid particle filter was used to collect the solid aerosol,and the condensation collection method was used to collect the liquid aerosol.The solid aerosol was collected in the solid particle filter in the form of solid particles,and the liquid aerosol was collected in the cold trap in the form of a condensate.Next,the amount of water-soluble anions in the solid aerosols and liquid aerosols was detected by ion chromatography using Dionex IonPac AS11-HC-4μm as the analytical column.The chromatographic separation conditions were as follows:flow rate,1 mL/min;column temperature,30℃;potassium hydroxide(KOH)concentration of the eluent,1 to 25 mol/L(linear increase)within 0-40 min;and injection volume,100μL.The ions were separated effectively within 40 min.The five anions showed good linear relationships in the range of 0.1-10 mg/L(correlation coefficients ranged from 0.9992 to 0.9997)and the detection limits were 0.02-0.04 mg/L.Finally,the sample collection conditions(sampling time,sampling temperature,and sampling flow rate)for the five water-soluble anions in the solid aerosols and liquid aerosols were optimized,and 2 h,-13℃,1.0 L/min were chosen.Under the optimized conditions,the amounts of the five anions in the solid and liquid aerosols of the actual samples were detected.The mass concentrations of F^-,Cl^-,NO^-₂,NO^-₃,and SO^2-₄ ions in the liquid aerosol of the actual sample were 5.7402μg/m³,1.1599μg/m³,3.3233μg/m³,2.4861μg/m³,and 0.9745μg/m³,respectively.The mass concentrations of F^-,Cl^-,NO^-₂,NO^-₃,and SO^2-₄ ions in the solid aerosol of the actual sample were 14.1037μg/m³,5.0398μg/m³,9.3052μg/m³,8.4528μg/m³,and 5.6314μg/m³,respectively.The method can be applied to the detection of actual atmospheric ions detection.In addition,the collection and analysis methods are suitable for exploring the collection and analysis conditions of other ions.