| 英文摘要 |
Assessment of residual concentration of alkenes and alkanes is crucial to evaluate the remediation efficiency of contaminated sites with chlorinated alkenes and alkanes. Chlorinated alkenes and alkanes are toxic, bio-accumulative, and persistent compounds that cause adverse effects on human health and the environment in cases of improper treatment. Analysis of alkenes and alkanes is commonly performed using chromatographic separation followed by non-mass spectrometric detection. However, conventional methods are time-consuming and are limited to the applicability of detectors. Moreover, the accuracy, i.e., false positive or false negative results, might be an issue. This project aims to develop an efficient method for the quantitative analysis of ethylene, ethane, and methane using mass spectrometry. Two sample preparation methods, i.e., deuteratedinternal-standards spiked samples and samples mixed with interferences, were utilized in this report. In addition, two sample introduction methods, i.e., via the direct injection and solid phase microextraction (SPME)-preconcentration, were used. Correlation coefficients (r) of 0.9995, 0.9985, and 0.9974 in the range of 1.28-1278.9, 1.28-1282.8, and 6.77-676.70 mg/L were obtained for deuteratedinternal-standards-spiked ethylene, ethane, and methane, respectively in the direct injection mode. r of 0.9993, 0.9999, and 0.9978 in the same range of concentrations were obtained for ethylene, ethane, and methane presenting in matrices, respectively, in the direct injection mode. Quality assurance and quality
control were implemented, and results indicated that the direction injection method is a reliable for quantitative analysis.
Second, solid phase microextraction (SPME) was utilized to upconcentrate analytes of interest. Carboxen/polydimethylsiloxane (CAR/PDMS) coating yielded the best result in this study. Extraction was completed in a minute. Signals were enriched by factors of 22.4±2.8 to 16.4±0.4 and 65.1±6.6 to 43.4±4.9 for ethylene and ethane, respectively, under different concentrations. Calibration curves in ranges of 1.28-1278.9、0.13-1282.8 mg/L were built for deuterated-internal-standards-spiked ethylene and ethane, respectively, where r of 0.992 and 0.999 were obtained. However, CAR/PDMS was not applicable to
methane. For ethylene and ethane in matrices, r of 0.9703 and 0.9852 were obtained, respectively. The SPME method yielded a high relative standard deviation (RSD) in the range of 6.16-39.29 %. In between shots, a re-generation time of 26 minutes at 290 °C was required for mitigating the carry-over effect. More parameters need to be conducted to achieve quantitative analysis. SPME was currently suggested to be a screening method for environmental trace analysis.
Third, a laboratory-built fieldable mass spectrometry integrating multiplexed ion sources is developed for real-time analysis. Capabilities of proton transfer reaction-selective reagent ion (PTR-SRI) and dielectric barrier discharge ionization (DBDI) for ethylene, ethane, and methane analysis are being improved. The performance of an internal electron ionization (iEI) source is being verified. Furthermore, efficiencies of sample introduction and ionization via electron impact are being optimized. Performance on detecting ethylene, ethane, and methane is being modified, even though none was detected in real samples. Ethylene and ethane were not detected using a commercial GC-MS in ten real samples. Methane was detected from 16.8 to 106.91 mg/L among ten real samples. Two workshops for technological innovation diffusion were held on the 24th of Oct. and the 31st of Oct. 2022.
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| 英文關鍵字 |
ethylene, ethane, methane, solid phase microextraction, gas chromatography-mass spectrometry, fieldable mass spectrometry, proton transfer reaction-selective reagent ion, dielectric barrier discharge ionization, internal electron ionization
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