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

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(4)(2-)) 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-4 μm 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, 100 μL. 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(4)(2-) ions in the liquid aerosol of the actual sample were 5.7402 μg/m(3), 1.1599 μg/m(3), 3.3233 μg/m(3), 2.4861 μg/m(3), and 0.9745 μg/m(3), respectively. The mass concentrations of F(-), Cl(-), NO(2)(-), NO(3)(-), and SO(4)(2-) ions in the solid aerosol of the actual sample were 14.1037 μg/m(3), 5.0398 μg/m(3), 9.3052 μg/m(3), 8.4528 μg/m(3), and 5.6314 μg/m(3), 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.