Gas Chromatography/Femtosecond Multiphoton Ionization/Time-of-Flight Mass Spectrometry of Dioxins

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• 作者：Yuka Watanabe-Ezoe ; Xing Li ; Tomoko Imasaka ; Tomohiro Uchimura ; Totaro Imasaka
• 刊名：Analytical Chemistry
• 出版年：2010
• 出版时间：August 1, 2010
• 年：2010
• 卷：82
• 期：15
• 页码：6519-6525
• 全文大小：209K
• 年卷期：v.82,no.15(August 1, 2010)
• ISSN：1520-6882

文摘

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) was developed for trace analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The use of an ultraviolet femtosecond laser (266 nm) allowed the sensitive, as well as selective, determination of PCDD/Fs with short singlet-excited-state lifetimes; the detection limit was 19 fg for 1,3,6,8-tetraCDF. Performance of the analytical instrument was examined and was ascertained to be satisfactory for all the criteria (K0311) prescribed by the Japanese Industrial Standards (JIS). The relative ionization efficiencies of ¹²C-native PCDD/Fs against ¹³C-labeled PCDD/Fs were 1.002 ± 0.012. This suggests that ¹³C-labeled isotopes can be used as internal standards with no intensity calibration and that the concentrations of PCDD/Fs can be determined to within an error of ca. 1%. In addition, multiphoton ionization provides negligible levels of background interference for the real soil samples even with curtailed pretreatment. The toxicity equivalence (TEQ) of the real sample was determined using GC/MPI/TOF-MS for performance evaluation against high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The results suggest equivalent or even superior performance for GC/MPI/TOF-MS, due to low background interference and to the ability to check the reliability of the assignment from the intensity distribution of the isotope peaks.