Determination of Dicarboxylic Acids in Fine Atmospheric Particles by Micro-Pressurized Liquid Extraction Coupled with Gas Chromatography-Mass Spectrometer

Abstract

Abstract The method of micro-pressurized liquid extraction (μ-PLE) coupled with gas chromatography-mass spectrometer (GC-MS) for analysis of 4 dicarboxylic acids (DCAs, including malonic acid, succinic acid, glutaric acid, and adipic acid) in fine atmospheric particles was developed. PM2.5 filter sample was extracted by μ-PLE at a pressure of 8 MPa and temperature of 80 °C using methanol as extraction solution. After two static 5-min extractions and a rinsing step with 100 μL methanol, about 500 μL of extraction solution was obtained. The extraction solution was then blown to dry with high purity nitrogen and submitted to a silylation reaction at 60 °C for 30 min. After internal standard (IS) was added, the derivatization solution was directly injected for GC-MS analysis. For quantification of 4 normally DCAs in fine atmospheric particles, the calibration curve was obtained with a good linear relationship in the range of 0.2–20 ng μL−1. The limits of quantification (LOQs, S/N = 10) were in the range of 0.15–0.47 ng m−3. The relative recoveries were between 92% and 122% with the RSDs between 2.6% and 11.8% for spiked filter samples. The method developed here was used to determine malonic acid, succinic acid, glutaric acid, and adipic acid in real PM2.5 samples collected from Xinghai Bay of Dalian city, and the results were determined to be 64.6, 50.0, 41.8 and 20.2 ng m−3, respectively.