GC-MS/MS Approaches for Chlorinated POPs Analysis: What’s Next After Dioxins and Furans. Validation and Comparative Data Evaluation

Vendor Lunch Speaker
Oral Presentation

Prepared by , B. Chandramouli

Contact Information: Bharat.Chandramouli@sgs.com;


ABSTRACT

Standard methods for the analysis of chlorinated dioxins and furans, PCBs, pesticides and other halogenated compounds currently use GC-HRMS to achieve high sensitivity, specificity, and reliable quantification. These techniques have produced decades-worth of data that has been used to inform many regulatory, remediation and litigation projects. Adoption of new approaches, such as GC-MS/MS, requires compatibility with existing regulatory and reference methods, quality criteria, and demonstrated equivalency of this data with GC-HRMS data.

Our objectives with this study were first to produce a method equivalent to EPA Method 1613B for PCDD/PCDF analysis by MS/MS, validate this method in water, soil and tissue samples compare performance in real-world complex samples and produce an “Alternate Test Method” (ATM) which we have submitted to the EPA. We have now extended this approach to PCB congener analysis by EPA Method 1668 and to chlorinated pesticides analysis.

Using a Waters APGC-TQ-XS MS/MS system, we developed full analytical methods for each analysis, including key QA features of the 1600 series methods. Sample workup and GC separation protocols were unchanged from the reference methods and all comparative tests were run using extracts that had been analyzed by GC-HRMS. We developed replacement techniques for mass-resolution and accuracy checks for detecting matrix effects that can cause lock-mass deviations (in HRMS) or the analogous ionization suppression (in MS/MS). We investigated known interferences including PCBs and polychlorinated diphenyl ethers in dioxin analysis. We then validated the methods by analysis of various environmental samples and comparison to HRMS results.

Calibration results all showed equivalent/better performance on all instrumental criteria including linearity, dynamic range and sensitivity. Validation data including precision, accuracy and method detection limits all showed excellent compliance with standard methods. Comparative data in complex matrix samples demonstrated method equivalence, and the quality protocols were successful in identifying the same interferences and confirmation of removal of interferences as the standard methods. In conclusion, we will present data that demonstrate that these AP-GC-MS/MS approaches are equivalent to the existing GC-HRMS methods.