| Title: | Room-temperature-ionic-liquid coated graphitized carbons for selective preconcentration of polar vapors |
| Author(s): | Wang J; Ma J; Zellers ET; |
| Address: | "Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, United States; Center for Wireless Integrated MicroSensing & Systems, University of Michigan, Ann Arbor, MI 48109-2122, United States. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, United States. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, United States; Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI 48109-2029, United States; Center for Wireless Integrated MicroSensing & Systems, University of Michigan, Ann Arbor, MI 48109-2122, United States. Electronic address: ezellers@umich.edu" |
| DOI: | 10.1016/j.chroma.2019.460486 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "Most adsorbent materials used for preconcentrating and thermally desorbing volatile and semi-volatile organic compounds (S/VOCs) in portable or 'micro' gas chromatographic (GC/microGC) instruments preferentially capture non-polar or moderately polar compounds relative to more polar compounds. Here, we explore the use of a known trigonal-tripyramidal room-temperature ionic liquid (RTIL) as a surface modifier for the graphitized carbons, Carbopack B (C-B) and Carbopack X (C-X), with the goal of enhancing their capacity and selectivity for polar S/VOCs. Breakthrough tests were performed by challenging tubes packed with approximately 2.5?ª+mg of C-B or RTIL-coated C-B (RTIL/C-B) with 13 individual S/VOCs, including several organophosphorus compounds and reference alkyl and aromatic hydrocarbons of comparable vapor pressures, at concentrations ranging from 14 to 130?ª+mg/m(3). The 10% breakthrough volume, V(b10), was used as the measure of capacity. For the RTIL/C-B, the V(b10) values of the five organophosphorus vapors tested were consistently approximately 2.5 times larger than those for the untreated C-B, and V(b10) values of the four non-polar reference vapors were 11-26 times smaller for the RTIL/C-B than for the untreated C-B. For compounds of similar vapor pressure the capacity ratios for polar vs. non-polar compounds with the RTIL/C-B ranged from 1.8 to 34. Similar results were obtained with C-X and RTIL/C-X on a smaller set of compounds. Tests at 70% relative humidity or with a binary mixture of a polar and non-polar compound had no effect on the capacity of the RTIL/C-B, and there were no changes in V(b10) values after several months of testing that included cycling from 25 to 250?ª+ degrees C. Capacity was strongly correlated with vapor pressure. Attempts to reconcile the selectivity using models based on linear-solvation-energy relationships were only partially successful. Nonetheless, these results indicate that RTIL coating of carbon adsorbents affords a simple, reliable means of rendering them selective for polar S/VOCs" |
| Keywords: | "Carbon/*chemistry Chromatography, Gas/instrumentation/*methods Gases/chemistry Graphite/chemistry Hydrocarbons, Aromatic/chemistry Ionic Liquids/*chemistry Temperature Volatile Organic Compounds/*chemistry Carbopack Ionic liquid Lser Organophosphonate Pre;" |
| Notes: | "MedlineWang, Junqi Ma, Jialiu Zellers, Edward T eng T42 OH008455/OH/NIOSH CDC HHS/ Evaluation Study Netherlands 2019/09/12 J Chromatogr A. 2020 Jan 4; 1609:460486. doi: 10.1016/j.chroma.2019.460486. Epub 2019 Aug 27" |
