Development of a Carbon Mesh Supported Thin Film Microextraction Membrane As a Means to Lower the Detection Limits of Benchtop and Portable GC/MS Instrumentation

Abstract

In this work, a durable and easy to handle thin film microextraction (TFME) device is reported. The membrane is comprised of poly(divinylbenzene) (DVB) resin particles suspended in a high-density polydimethylsiloxane (PDMS) glue, which is spread onto a carbon fiber mesh. The currently presented membrane was shown to exhibit a substantially lesser amount of siloxane bleed during thermal desorption, while providing a statistically similar extraction efficiency toward a broad spectrum of analytes varying in polarity when compared to an unsupported DVB/PDMS membrane of similar shape and size which was prepared with previously published methods. With the use of hand-portable GC-TMS instrumentation, membranes cut with dimensions 40 mm long by 4.85 mm wide and 40 ± 5 μm thick (per side) were shown to extract 21.2, 19.8, 18.5, 18,4, 26.8, and 23.7 times the amount of 2,4 dichlorophenol, 2,4,6 trichlorophenol, phorate D10, fonofos, chloropyrifos, and parathion, respectively, within 15 min from a 10 ppb aqueous solution as compared to a 65 μm DVB/PDMS solid phase microextraction (SPME) fiber. A portable high volume desorption module prototype was also evaluated and shown to be appropriate for the desorption of analytes with a volatility equal to or lesser than benzene when employed in conjunction with TFME membranes. Indeed, the coupling of these TFME devices to hand-portable gas chromatography toroidial ion trap mass spectrometry (GC-TMS) instrumentation was shown to push detection limits for these pesticides down to the hundreds of ppt levels, nearing that which can be achieved with benchtop instrumentation. Where these membranes can also be coupled to benchtop instrumentation it is reasonable to assume that detection limits could be pushed down even further. As a final proof of the concept, the first ever, entirely on-site TFME-GC-TMS analysis was performed at a construction impacted lake. Results had indicated the presence of contaminants such as toluene, ethylbenzene, xylene, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and tris(1-chloro-2-propyl)phosphate, which stood out from other naturally occurring compounds detected.

Development, Optimization and Applications of Thin Film Solid Phase Microextraction (TF-SPME) Devices for Thermal Desorption: A Comprehensive Review

“…The geometry of the earlier developments of the technique was cumbersome, its large volume required specially suited large-volume injectors which not all labs were equipped for [12]. On a more fundamental note, an increase of extraction phase volume consequently increases the amount of background and bleed from the extraction phase itself and this critical drawback has only recently been addressed by newer generations of TF-SPME devices [19]. Although the desorption of TF-SPME devices can be fully automated, their geometry still poses a barrier for online extraction and analysis, and currently an auto-sampler that can both perform extraction and desorption for conventional TF-SPME devices has yet to be developed.…”

“…Since the advent of thermally stable extractive phases and binders, the TD of sorbents has been an attractive method for sample introduction to analytical instrumentation, as it requires no additional organic solvent as many other methods do [7][8][9]21]. As the science and engineering behind these thermally stable phases progress, the inherent background of newly developed phases (solid or liquid) is reduced, thus allowing the TD of appropriate sorbents to be applicable to ultra-trace level analysis [19,29,30]. Fundamentally, TD operates by heating a sorbent with hot gas to release all volatile analytes adsorbed onto the extraction phase, the increase in temperature driving the partition coefficient of the analytes to favor the gas phase thus releasing them from the sorbent.…”

“…Depending on the cryo-trap device used, the trap can be cooled by liquid gas (such as nitrogen and carbon dioxide) or a solid-state device. In the use of a cryo-trapping device, while the analytes are desorbed at high temperature in the TDU, the cryo-trap is held at a low temperature, −40 to 0 • C being appropriate for most volatiles [16,32,33] with highly volatile substances requiring lower temperatures trending toward −150 • C to properly pre-focus [8,19,29,[34][35][36]. Only after all compounds are thermally desorbed from the TF-SPME device and condensed in the cryo-trap, the temperature of the cryo-trap is increased at a high rate (usually 12 • C/s), achieving discrimination-free transfer of analytes into the analytical column with minimal sample loss.…”

Fabric Sol–gel Phase Sorptive Extraction Technique: A Review

“…The resulted samplers presented better stability and robustness thanks to the incorporation of the fabric substrate in their thin film structure. Recently, a carbon mesh support was presented by Grandy et al, as an alternative substrate for the TFME technique [15] for GC-toroidial ion trap MS (GC-TMS) analysis. The proposed carbon substrate seems to be more durable than other TFME designs.…”

Investigation of 1-Dodecylimidazolinm Modified Filter Papers as a Thin-Film Microextraction Phase for the Preconcentration of Bisphenol A from Plant Oil Samples

“…This change in geometry can practically increase the extraction recovery of analytes without sacrificing the analysis time due to the large extraction phase surface area-to-volume ratio of the adsorption thin-films. 15,16 Some reported applications of TFME have been published in different matrixes, such as biological matrixes, 17 water, 15,[18][19][20][21] indoor air, 22 human exhaled breath condensates 23 and wine. 24 Filter paper, as 100% naturally derived cellulose nanofibers with a surface area of larger than 100 m 2 /g, 25 has been used as a platform in analytical and clinical chemistry because it is affordable, sustainable, hydrophilic, inert, and stable over a broad range of pH/ionic strengths.…”