Optimizing solvent extraction methods for activated carbon-based passive samplers in atmospheric volatile organic compound analysis: minimizing analytical interferences from pretreatment solvents and ensuring quantitative reliability.

Abstract

A passive sampler was used to effectively monitor trace volatile organic compound (VOC) concentrations in the atmosphere. VOCs are typically extracted from passive samplers using CS₂, which is a volatile and hazardous chemical that can leave residues and damage the mass spectrometry (MS) system during gas chromatography (GC)-MS. This study aims to develop and validate alternative solvent extraction methods using acetone, ethanol, n-hexane, and a solution of 99% acetone and 1% CS₂ (ATCS) for VOCs from passive samplers using a standard GC-MS system. ATCS had the highest VOC extraction efficiency with the average value of 42.4 ± 21.4%, followed by acetone at 29.9 ± 17.6%. Ethanol and n-hexane exhibited extraction efficiencies of less than 9%. Despite the ATCS extraction efficiency of less than 50%, it demonstrated excellent analytical reproducibility (relative standard deviation of 1.62 ± 0.64%) and detection limit of 20.5 ± 12.9 ppt, which was significantly lower than 1 ppb. When used to extract and analyze VOCs from ambient air samples, ATCS yielded VOC concentrations of 0.57 ± 0.33 ppb, consistent with urban air levels. The variance in the outdoor VOC concentrations was less than 0.1 ppb, confirming its high reproducibility. Thus, the ATCS solvent extraction method developed in this study enables the accurate quantification of trace VOCs below 1 ppb, reduces MS damage, and mitigates health risks to analysts using GC-MS.