Development of a Hydrophilic Lipophilic Balanced Thin Film Solid Phase Microextraction Device for Balanced Determination of Volatile Organic Compounds

Abstract

A novel hydrophilic-lipophilic balanced (HLB) thin film solid-phase microextraction (TF-SPME) device is proposed for polarity-balanced determinations of volatile organic compounds. The proposed HLB particles used in the preparation of these membranes were prepared using a precipitation polymerization technique and determined to have a specific surface area of 335 m²/g with an average pore diameter of 13 Å. Membranes prepared from these particles were found to extract 1.8, 2.2, 1.9, 1.7, 2.0, and 1.3 times more benzene, 2-pentanone, 1-nitropropane, pyridine, 1-pentanol, and octane, respectively, than the established divinylbenzene/polydimethylsiloxane (DVB/PDMS)-based membranes. Furthermore, membranes prepared from these lab-made particles were shown to extract significantly ( p = 0.00047) larger amounts of these analytes than membranes prepared from comparative commercial HLB particles. The intermembrane extraction efficiency between 3 membranes was determined to be reproducible at 95% confidence for 4 different coating chemistries tested, including the DVB/PDMS membranes, and those prepared with 3 different HLB compositions. Furthermore, method reliability was established by confirming that, once extracted, modified McReynolds standards were stable on the HLB/PDMS membranes stored in thermal desorption tubes on an autosampler rack for at least 120 h, for 5 of the 6 standards, but only for 24 h for pyridine at a 95% level of confidence. Finally, using a TF-SPME enabled, portable GC/MS instrument, an entirely on-site proof of concept application was performed for the determination and quantitation of chlorination byproducts in a private hot tub, successfully identifying chloroform, bromodichloromethane, dichloroacetonitrile, chlorobenzene, benzonitrile, and benzyl chloride, while further quantifying chloroform and dichloroacetonitrile at levels of 270 and 79 ppb with %RSD values of 13% and 5%, respectively.