Detection of Persistent Organic Pollutants Using Atmosheric Pressure Gas Chromatography and a Novel Acquisition Mode for Quadruple Time-of-Flight MS
Oral Presentation
Prepared by K. Rosnack1, L. Mullin1, K. Graham1, G. Cleland1, A. Ladak2, I. Ericson Jogsten3, B. van Bavel3
1 - Waters Corporation, 34 Maple Street, Milford, MA, 01757, United States
2 - Waters Corporation, 100 Cummings Center, Ste 407N, Beverly, MA, 01915, United States
3 - Orebro University, MTM Research Centre, SE-701 82, Orebro, , Sweden
Contact Information: [email protected]; 508-482-4639
ABSTRACT
The detection of persistent organic pollutants (POPs) must meet low regulatory limits, typically on the order of sub ppb-levels in complex environmental matrices. Additionally, the identification of product ions for confirmatory identification is important and can be achieved using MRM transitions. The following work shows the utility of a novel data acquisition mode for quadrupole time-of-flight MS which utilizes a targeted enhancement of selected product ions. This acquisition mode is demonstrated for the detection of polychlorinated dibenzo p-dioxins and furans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and other POPs in a complex biological sample.
Established gas chromatography injector and oven conditions were employed with atmospheric pressure chemical ionization. Data was acquired on a quadrupole time-of-flight MS using targeted enhancement of product ions established in previous studies for selected PCDD/Fs. Simultaneous full scan data was also acquired in the same injection. Calibration standards of PCDD/Fs were prepared across 3 orders of magnitude, and were assessed for linearity. Preliminary sample batches of whale blubber extracts were analyzed. These samples were also qualitatively investigated for the presence of additional environmental contaminants. Identifications were obtained using comparisons of exact mass, isotope distribution patterns and searching of online databases.
Previous assessments comparing sensitivity using the targeted enhancement method applied here show increased sensitivity of MS signal by at least 5 times over normal full scan mode. This is achieved by the focusing of the quadrupole on a specified precursor ion, followed by an enhanced duty cycle on named product ions. Product ions are generated by CID in one of two collision cells prior to targeted enhancement. As the two commonly monitored product ions of PCDD/Fs are respective 35Cl and 37Cl isotopes, targeted enhancement of the average mass was found most suitable. Increased sensitivity was evident for PCDD/Fs monitored in this targeted experiment. Moreover, the main advantage for using this acquisition method was the reduction of noise, afforded by the focused quadrupole and enhanced duty cycle. The most toxic known PCDD congener (2,3,7,8-TCDD) was detected in the lowest calibration standard, at 100 fg. For the same congener, linearity was acceptable with an R2 value of 0.996. The masses of selected PBDEs were extracted from the full scan data, and positive identifications of several congeners in the blubber extracts. Based on this preliminary work, future analyses are intended in other complex biological matrices for PCDD/Fs.
Oral Presentation
Prepared by K. Rosnack1, L. Mullin1, K. Graham1, G. Cleland1, A. Ladak2, I. Ericson Jogsten3, B. van Bavel3
1 - Waters Corporation, 34 Maple Street, Milford, MA, 01757, United States
2 - Waters Corporation, 100 Cummings Center, Ste 407N, Beverly, MA, 01915, United States
3 - Orebro University, MTM Research Centre, SE-701 82, Orebro, , Sweden
Contact Information: [email protected]; 508-482-4639
ABSTRACT
The detection of persistent organic pollutants (POPs) must meet low regulatory limits, typically on the order of sub ppb-levels in complex environmental matrices. Additionally, the identification of product ions for confirmatory identification is important and can be achieved using MRM transitions. The following work shows the utility of a novel data acquisition mode for quadrupole time-of-flight MS which utilizes a targeted enhancement of selected product ions. This acquisition mode is demonstrated for the detection of polychlorinated dibenzo p-dioxins and furans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and other POPs in a complex biological sample.
Established gas chromatography injector and oven conditions were employed with atmospheric pressure chemical ionization. Data was acquired on a quadrupole time-of-flight MS using targeted enhancement of product ions established in previous studies for selected PCDD/Fs. Simultaneous full scan data was also acquired in the same injection. Calibration standards of PCDD/Fs were prepared across 3 orders of magnitude, and were assessed for linearity. Preliminary sample batches of whale blubber extracts were analyzed. These samples were also qualitatively investigated for the presence of additional environmental contaminants. Identifications were obtained using comparisons of exact mass, isotope distribution patterns and searching of online databases.
Previous assessments comparing sensitivity using the targeted enhancement method applied here show increased sensitivity of MS signal by at least 5 times over normal full scan mode. This is achieved by the focusing of the quadrupole on a specified precursor ion, followed by an enhanced duty cycle on named product ions. Product ions are generated by CID in one of two collision cells prior to targeted enhancement. As the two commonly monitored product ions of PCDD/Fs are respective 35Cl and 37Cl isotopes, targeted enhancement of the average mass was found most suitable. Increased sensitivity was evident for PCDD/Fs monitored in this targeted experiment. Moreover, the main advantage for using this acquisition method was the reduction of noise, afforded by the focused quadrupole and enhanced duty cycle. The most toxic known PCDD congener (2,3,7,8-TCDD) was detected in the lowest calibration standard, at 100 fg. For the same congener, linearity was acceptable with an R2 value of 0.996. The masses of selected PBDEs were extracted from the full scan data, and positive identifications of several congeners in the blubber extracts. Based on this preliminary work, future analyses are intended in other complex biological matrices for PCDD/Fs.
