Low level quanti fication of PCDD/Fs in animal feedstuffs using the Thermo Scientific TSQ 9000 GC-MS/MS system with AEI source

Significance of the Topic

Polychlorinated dibenzo p dioxins and polychlorinated dibenzo furans commonly known as dioxins are highly toxic persistent organic pollutants that bioaccumulate in animal fat and enter the human food chain primarily through meat dairy fish and shellfish. Due to their endocrine immune and carcinogenic effects regulatory bodies enforce stringent maximum levels in food and animal feed while requiring analytical methods capable of reliable quantification at one fifth of these limits.

Objectives and Study Overview

This study evaluates the performance of the Thermo Scientific TSQ 9000 triple quadrupole GC MS MS system equipped with an Advanced Electron Ionization source for the quantification of PCDD Fs in animal feedstuffs. Key aims include demonstrating compliance at one fifth of EU maximum levels assessing sensitivity selectivity and robustness and verifying routine suitability across diverse sample matrices.

Used Instrumentation

• Thermo Scientific TSQ 9000 triple quadrupole mass spectrometer with AEI source
• Thermo Scientific TRACE 1310 GC system
• Thermo Scientific TriPlus RSH autosampler
• Thermo Scientific LinerGOLD single taper liners and TraceGOLD TG Dioxin GC column (60 m x 0 25 mm 0 25 µm)
• Chromeleon 7 2 chromatography data system with eWorkflows and integration to SampleManager LIMS SDMS LES

Methodology

Feed samples including alfalfa pork fat premix and sheep feed were supplied by a reference institute. European method EN 1948 standard solutions were used for calibration and quantitation. Key GC parameters included a splitless injection at 280 °C helium carrier gas at 1 2 mL/min and an oven program from 120 to 320 °C over 39 7 min. The MS operated in timed SRM mode with an AEI source at 300 °C electron energy 50 eV collision gas argon at 70 psi and unit mass resolution on both quadrupoles. Calibration covered 0 01 to 320 pg/µL with internal standard recovery correction. The limit of quantification was defined as the lowest calibration point with relative response deviation below 30 percent.

Main Results and Discussion

• Chromatographic separation achieved better than 25 percent peak to peak resolution for critical isomer pairs such as HxCDF congeners.
• Instrumental detection limit for 2 3 7 8 TCDD was below 0 6 fg on column demonstrating attogram sensitivity.
• On column LOQs ranged from 20 fg for low chlorinated congeners to approximately 300 fg for OCDD and OCDF complying with sample intake as low as 5 g.
• Response factors exhibited excellent linearity over the calibration range with RSDs between 1 8 and 7 3 percent.
• Ion ratio stability remained within plusminus15 percent across a two day sequence confirming robustness for both native and labelled congeners.
• Quality control feed samples showed upper bound total TEQ values significantly lower than one fifth of the maximum level providing confidence in method accuracy.
• Real sample analyses of alfalfa premix pork fat and sheep feed all produced TEQ values below regulatory limits.

Benefits and Practical Applications

The TSQ 9000 GC MS MS with AEI source offers high sensitivity and selectivity allowing reliable quantification of PCDD Fs at sub femtogram levels. The low sample intake requirement and robust performance facilitate routine monitoring in quality control laboratories ensuring compliance with EU legislation and reducing human exposure risk.

Future Trends and Potential Applications

• Further lowering detection limits through advanced ionization source designs and microfluidic GC interfaces.
• Integration of automated sample preparation and AI driven data evaluation to enhance throughput and reduce operator intervention.
• Expansion of the method to other persistent organic pollutants and complex environmental and biological matrices.
• Real time monitoring and remote data access via cloud connected laboratory information management systems.

Conclusion

The Thermo Scientific TSQ 9000 GC MS MS system equipped with an AEI source meets current EU requirements for dioxin analysis in feedstuffs delivering attogram sensitivity stable quantitation and robust ion ratio performance. This method provides an effective tool for routine compliance monitoring and risk management in the food supply chain.

Reference

• European Commission Directive 2002/32/EC on undesirable substances in animal feed
• EN 1948 Determination of PCDD/Fs in food and feed by HRGC HRMS Wellington Laboratories Inc