Development of porous carbon/polydimethylsiloxane thin-film solid-phase microextraction membranes to facilitate on-site sampling of volatile organic compounds

This work presents the development of carboxen/polydimethylsiloxane (Car/PDMS) based thin film-solid phase microextraction (TF-SPME) method capable of identifying volatile organic compounds (VOCs) in hot-tub-air and human-breath samples. The proposed TF-SPME membranes were developed using carbon mesh sheets loaded with Car/PDMS and nanocarbon/polydimethylsiloxane (NCar/PDMS) sorbents consistent with sustainable chemistry principles. The membrane surfaces were examined using a stereo microscope system and were evaluated based on the effect of various particle ratios (1%, 2.5%, 5%, 10%, and 15%). The results showed that membranes with higher particle ratios provided a higher extraction efficiency when used with McReynolds standards; however, membranes containing 10% and 15% carbon were fragile and suffered from substantially higher background bleed. Hence, a sorbent with a 5% particle ratio was deemed to be optimal, and the carboxen coating was found to capture the highest amounts of the McReynolds standard. Moreover, Car/PDMS and NCar/ PDMS were found to provide good repeatability, as their intra-membrane %RSDs fell within an acceptable range-1.2%-21.9% and 1.7%-20%, respectively-for all analytes tested. Finally, for proof-of-concept applications, the developed membranes were used to sample chlorination by-products (chloroform and dichloroacetonitrile) from hot tub headspace and were identified using a hand portable gas chromatography-mass spectrometry (GC-MS) system. In second application 33 VOCs in human-breath samples sampled and identified using a benchtop GC-MS system.

Automated summary

A Car/PDMS based TF-SPME method was developed for identifying VOCs in hot tub air and human breath samples. Membranes with a 5% particle ratio were found to be optimal for extraction efficiency, with Car/PDMS coating capturing the highest amounts of target compounds. Both Car/PDMS and NCar/PDMS showed good repeatability for all analytes tested, making them suitable for various applications.