Gura Sigalit, Tarifa Anamary, Mulloor Jerome, Torres Michelle N, Almirall José R
Department of Chemistry and Biochemistry, International Forensic Research Institute, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA.
Anal Chim Acta. 2018 Jul 19;1014:27-40. doi: 10.1016/j.aca.2018.01.043. Epub 2018 Feb 14.
A novel phenyl modified PDMS (PhPDMS) sol-gel adsorption phase was developed for use with the capillary microextraction of volatiles (CMV) device, and determined to provide significant enhancement in BTEX recoveries when sampling trace (ng) amounts of these volatiles at ambient conditions. The previously reported reusable PDMS-CMV device has been demonstrated to rapidly and efficiently extract target compound's vapors in forensic and environmental applications. An improved recovery for VOCs was achieved with a cryofocusing system while extracting at -10 C, but it was found to be impractical for field sampling. This report details a modification to the CMV's chemistry, by the successful introduction of phenyl groups to the PDMS sol-gel adsorption phase, allowing enhanced performance at ambient extraction conditions. Higher average recoveries, determined through a broad concentration range, were demonstrated for PhPDMS-CMV over its original PDMS-CMV, from cans simulating a closed space set-up. Within 7.8 (±10%) and 3.5 (±6%) folds higher for benzene and toluene, respectively and 2 (±2%) folds for ethylbenzene and xylenes. Significant higher retaining capabilities were demonstrated also at the more challenging set-up, simulating an open space environment. Whereas, benzene had completely breakthrough the PDMS-CMV, its reliable detection was still confirmed with PhPDMS-CMV pumping at 2 L or 6 L air, concentration dependent. At least 50 folds (±26%) more toluene was retained with PhPDMS-CMV at 6 L air than with PDMS-CMV. The enhanced overall performance lead to determination of trace LODs with the new CMV of 0.002, 0.00035 and 0.00015 ppm for benzene, toluene, ethyl benzene and xylenes, respectively. As proof of concept, for the first time solvent extraction is presented for the new CMV as an alternative to thermal desorption extraction. Extraction efficiencies of 60% for TEX, and lower concentration dependent for benzene, were demonstrated with the ease and rapid application of 100 μL acetone through the device. The improvements described in this study continues to build on the potential for the use of the reusable new CMV device by expanding its possible potential applications for fast and sensitive air sampling of VOCs. The solvent extraction step may offer compatibility with LC-based systems.
一种新型的苯基改性聚二甲基硅氧烷（PhPDMS）溶胶 - 凝胶吸附相被开发用于挥发性物质的毛细管微萃取（CMV）装置，并确定在环境条件下对痕量（纳克）挥发性物质进行采样时，能显著提高苯系物的回收率。先前报道的可重复使用的PDMS - CMV装置已被证明在法医和环境应用中能快速有效地萃取目标化合物的蒸汽。在 - 10°C下萃取时，通过低温聚焦系统实现了挥发性有机化合物回收率的提高，但发现其对于现场采样不实用。本报告详细介绍了对CMV化学性质的改进，成功地将苯基引入到PDMS溶胶 - 凝胶吸附相中，从而在环境萃取条件下实现了性能的提升。通过模拟封闭空间设置的罐子，在较宽的浓度范围内测定，PhPDMS - CMV相对于其原始的PDMS - CMV具有更高的平均回收率。苯和甲苯的回收率分别提高了7.8（±10%）倍和3.5（±6%）倍，乙苯和二甲苯提高了2（±2%）倍。在模拟开放空间环境这一更具挑战性的设置中，也展示了显著更高的保留能力。虽然，苯已完全穿透PDMS - CMV，但通过PhPDMS - CMV以2L或6L空气泵吸时，仍能可靠检测到苯，这取决于浓度。在6L空气条件下，PhPDMS - CMV保留的甲苯比PDMS - CMV至少多50倍（±26%）。整体性能的提升使得新型CMV对苯、甲苯、乙苯和二甲苯的痕量检测限分别为0.002、0.00035和0.00015ppm。作为概念验证，首次展示了新型CMV的溶剂萃取方法，作为热解吸萃取的替代方法。通过该装置轻松快速地加入100μL丙酮，对TEX的萃取效率为60%，对苯的萃取效率则较低且与浓度有关。本研究中描述的改进继续基于可重复使用的新型CMV装置的潜力，通过扩大其在挥发性有机化合物快速灵敏空气采样方面的潜在应用。溶剂萃取步骤可能与基于液相色谱的系统兼容。
