High Performance Gas Chromatography Time of Flight Mass Spectrometry Analysis of Halogenated Organic Compounds in Pet Food

Importance of the topic

The analysis of halogenated organic compounds (HOCs) in pet food is critical due to their widespread use as pesticides, flame retardants and industrial additives. These persistent, lipophilic pollutants can migrate into animal feed and pose serious health risks through bioaccumulation and biomagnification. Reliable analytical methods are therefore essential to ensure food safety and regulatory compliance.

Objectives and Study Overview

This study evaluates the performance of a high-resolution gas chromatography time-of-flight mass spectrometer (GC-TOFMS) with Folded Flight Path (FFP™) technology for the characterization of a broad range of HOCs in cat and dog food. Key goals include comparing sample cleanup strategies, assessing mass accuracy and resolving power, and demonstrating the instrument’s ability to distinguish coeluting isobaric species.

Methodology and Instrumentation

Sample Preparation:

• Pet food (1 g) spiked with surrogate standards (28 PCBs at 10 µg/mL) and homogenized in acetonitrile by QuEChERS salts.
• Dispersive SPE cleanup variants: Resprep Q213 (150 mg MgSO₄, 25 mg PSA, 7.5 mg GCB) and Resprep Q252 (150 mg MgSO₄, 50 mg PSA, 50 mg C₁₈, 50 mg GCB).
• Extracts spiked with internal standards (BDE-118, BB-209) and analyzed directly or after cleanup.

Chromatography and Mass Spectrometry:

• GC: Agilent 7890, Restek Rtx-1614 column (15 m × 0.25 mm, 0.18 µm film).
• Injection: splitless, 2 µL at 250 °C.
• Oven: 70 °C (1 min) to 320 °C at 20 °C/min (1.5 min).
• Carrier gas: He, 1.00 mL/min.
• MS: LECO Pegasus GC-HRT; EI source; HR mode (R≈25 000), UHR mode (R≈50 000); m/z 50–1000; 6 spectra/s.

Main Results and Discussion

Cleanup Performance and Matrix Removal:

• Resprep Q252 provided the most effective removal of fatty acids and sterols, yielding clean extracts with minimal matrix interferences.
• Direct extracts (no cleanup) still produced quality data in UHR mode, demonstrating the instrument’s selectivity.

Resolution and Mass Accuracy:

• High resolution mode resolved isobaric interferences such as BDE-47 vs. PCBs at nominal m/z 324.
• Mass accuracy for representative compounds (octadecanoic acid, cholesta-3,5-diene) was better than 0.2 ppm in HR and below 0.01 ppm in UHR.
• Calculated resolution exceeded 23 000 (m/Δm) in UHR for characteristic ions.

Screening Capability:

• Targeted and untargeted HOCs (PCBs, PBDEs, DBDPE, HBCD, dechlorane plus) were confidently identified via library matching (814–874/1000 similarity).
• Complex environmental and food matrices were successfully analyzed without extensive cleanup.

Benefits and Practical Applications

This methodology enables simultaneous quantification and screening of regulated POPs and emerging HOCs in pet food. High resolution and accurate mass reduce false positives from coeluting species, simplifying workflow by lowering cleanup demands. Laboratories conducting routine quality control and environmental monitoring can adopt this approach for rapid, reliable analysis.

Future trends and opportunities

Advancements may include expanded spectral libraries for novel halogenated compounds, automation of QuEChERS workflows, and coupling with software for real-time screening. Further application to other food matrices, feedstocks and environmental samples will broaden the impact of high-resolution GC-TOFMS.

Conclusion

The LECO Pegasus GC-HRT system delivers the resolution, mass accuracy and sensitivity required to analyze complex pet food matrices for a wide range of HOCs. Its ability to resolve isobaric interferences and operate effectively with minimal cleanup enhances throughput and confidence in regulatory compliance testing.

Reference

No formal reference list was provided in the original text.