Green sampling of gas-phase volatile organic compounds using time-weighted average solid phase microextraction and gas chromatography - mass spectrometry: A critical review

Time-weighted average solid-phase microextraction (TWA-SPME) is a solvent-free passive sampling technique increasingly applied to volatile organic compounds (VOCs) monitoring in air. This review critically examines the theoretical foundations of TWA-SPME based on Fick’s laws of diffusion, highlights optimization of SPME coating, diffusion path length, and sampling duration, and compares quantification strategies based on both theoretical modeling and empirical calibration. Applications across ambient and indoor air, vehicle exhaust, industrial emissions, and clinical environments demonstrate their versatility and sensitivity relative to conventional sorbent-based methods. A greenness evaluation using the AGREEprep tool confirmed strong TWA-SPME alignment with green sampling preparation principles, particularly through elimination of solvents, low waste, and high operator safety. Challenges such as adsorption on metallic components and coating saturation are discussed alongside mitigation strategies and device refinements. Emerging designs and simulation-based models improve performance predictability and sampling efficiency under diverse environmental conditions. Comparisons with emerging alternatives such as thin-film SPME and needle trap devices highlight the unique advantages of TWA-SPME in robustness, simplicity, and reproducibility. Overall, TWA-SPME represents an environmentally friendly, accurate, and practical approach to VOC sampling, with growing relevance in environmental monitoring and occupational exposure assessments.