Optimization of activated carbon cloth for the recovery of gasoline: analysis by GC-MS and DART-MS
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Abstract
Current fire debris analysis methods involve the use of Activated Charcoal Strips (ACS) and Gas Chromatography-Mass Spectrometry (GC-MS). Currently, a jar of 100 ACS costs $720.00 with no other commercially available alternatives. Other cost-effective adsorbent technologies such as Activated Carbon Cloth (ACC) should be explored along with analysis by Direct Analysis in Real Time-Mass Spectrometry (DART-MS). ACC is a technology that is cost efficient, commercially available, and can be modified by the user for the desired purpose. A comparison of solvent desorption with GC-MS and thermal desorption utilizing DART-MS was attempted.Heated passive headspace concentration was performed as the extraction method to compare the performance of gasoline recovery by the ACC and ACS. The following variables were tested for comparison: placing the adsorbents in the same paint can during extraction, varying volumes of gasoline, varying stages of weathered gasoline, diesel fuel, and desorption solvent. The evaluation of these variables was analyzed using the traditional method of GC-MS and integrating the area under the chromatographic peaks produced. The total integrated peak area served as a semi-quantitative measure of recovery in order to compare adsorbent performance. The extracts that were prepared for GC-MS were additionally analyzed by DART-MS. The ACC strips were analyzed directly by DART-MS in an attempt to thermally desorb the analytes off of the cloth.
The adsorbents performed comparably when recovering neat gasoline among the various variables mentioned. The ACC performed better than the ACS at recovering evaporated gasoline up to 75%. Above 75% evaporated gasoline, the ACS recovered more hydrocarbons than the ACC. The ACS also performed better when recovering diesel fuel. The ACC outperformed the ACS when using carbon disulfide as the desorption solvent. The mass spectral data of the extracts by DART-MS appeared similar to the solvent blanks analyzed. Concentrating the extracts to a 1:4 dilution did not improve the results. Thermal desorption of neat gasoline pipetted onto the ACC strips did not result in any profiles that resembled gasoline. DART-MS is not a viable technology to analyze fire debris extracts or adsorbents by thermal desorption at this time. The ACC proved to be a comparable adsorbent technology to the traditional ACS; therefore, crime laboratories could consider using the ACC to extract gasoline from fire debris.
Description
2025