Detection and Quantitation of Brominated and Chlorinated Hydrocarbons by DART with Linear Ion Trap and Triple Quadrupole Technology

Significance of the Topic

Persistent halogenated hydrocarbons such as brominated flame retardants (BFRs) and organochlorine pesticides (OCs) pose long-term environmental and health hazards due to their stability and bioaccumulative potential. Rapid and reliable monitoring of these analytes is vital for regulatory compliance, environmental risk assessment, and protection of public health.

Conventional chromatographic workflows demand extensive sample preparation and method development. The direct analysis in real time (DART) approach offers a streamlined alternative, reducing analytical turnaround and resource consumption while delivering robust detection of trace contaminants.

Objectives and Study Overview

This study aimed to evaluate a DART-based workflow for qualitative and quantitative analysis of representative BFRs and OCs. Key goals included confirmation of precursor and fragment ions using two mass analyzers, determination of method sensitivity, and demonstration of applicability to real water samples.

Methodology and Sample Preparation

Standards of nine brominated and one chlorinated compound were prepared in acetone at concentrations ranging from 10 ppb to 100 ppm. Kepone served as an internal reference at 100 ppb in all samples. Spiked and unspiked water aliquots were analyzed directly without additional cleanup.

DART-SVP ionization was performed in two modes:

• 1D transmission: grid 300 V, gas temperature 200 °C (linear ion trap) or 400 °C (triple quadrupole).
• Direct infusion: syringe pump at 1–5 µL/min for optimization of ionization and fragmentation conditions.

Used Instrumentation

• Thermo Scientific LTQ linear ion trap MS with DART-SVP source.
• Thermo Scientific TSQ Quantum Access MAX triple quadrupole MS with DART-SVP source.

Main Results and Discussion

All compounds except three were detected by the linear ion trap; the missing analytes were recovered with increased DART temperature on the TSQ system. Observed ionization pathways varied by molecular structure: non-aromatic hydrogen sites favored deprotonation ([M–H]⁻), while aromatic systems underwent hydroxide addition and HBr loss. Collision energy ramping on the TSQ enabled selection of sensitive SRM transitions.

Calibration demonstrated limits of detection as low as 50 ppb for several analytes. Quantitation of a San Francisco water sample spiked at 500 ppb revealed matrix-dependent signal variation, underlining the necessity of matrix-matched standards or isotope-labeled internal calibrants.

Benefits and Practical Applications

The DART approach delivers:

• Rapid screening without chromatographic separation.
• Minimal sample preparation, enabling high throughput.
• Comprehensive precursor and fragment ion information for confident identification.
• Sensitivity sufficient for regulatory monitoring of BFRs and OCs in environmental waters.

Future Trends and Opportunities

Further enhancements may include integration of isotope-labeled standards to correct spot-to-spot variability, automated DART-MS methods for large compound panels, and coupling with high-resolution mass analyzers for improved selectivity. Expansion to solid and biological matrices could broaden surveillance capabilities.

Conclusion

The combined use of DART-SVP ionization with linear ion trap and triple quadrupole mass spectrometers presents a viable platform for fast, reliable detection and quantitation of brominated and chlorinated hydrocarbons. The workflow minimizes sample handling while delivering essential structural information and quantitative performance suitable for environmental monitoring.

References

• de Wit CA, Kierkegaard A, Ricklund N, Sellström U, Eljarrat E, Barceló D (eds). Emerging Brominated Flame Retardants in the Environment. Springer-Verlag Berlin Heidelberg; Published online 9 December 2010.