Rapid and simple determination of low level fipronil and amitraz in egg samples using the Bruker EVOQ™ LC-TQ Elite MS/MS system

Significance of the Topic

This study addresses the critical need for rapid, sensitive, and reliable detection of fipronil and amitraz residues in eggs. Following high-profile food safety alerts in 2017, regulatory limits in the EU (0.005 mg/kg for fipronil and 0.01 mg/kg for amitraz) demand analytical methods capable of quantifying trace levels in complex biological matrices. Ensuring consumer safety and compliance with ISO 17025 and SANTE guidelines requires streamlined workflows with robust performance.

Objectives and Study Overview

The primary aim was to develop and validate a fast liquid–liquid extraction (LLE) method coupled to Bruker EVOQ LC-TQ Elite MS/MS for quantitation of fipronil, its sulfone metabolite, amitraz, and an amitraz metabolite (DMPF) in egg samples at low ppb levels. Key goals included simplicity of sample preparation, unattended analysis, and meeting method reporting limits (MRL) of 5 µg/kg.

Methodology and Instrumentation

Sample preparation involved:

• Weighing 2 g homogenized egg into a 20 mL tube
• Adding 2 mL acetonitrile, shaking 30 s, centrifuging at 4000 rpm
• Filtering 1 mL supernatant through 0.22 µm nylon
• Spiking with triphenylphosphate as internal standard

Instrumentation Used

The method employed:

• Bruker EVOQ LC-TQ Elite MS/MS with heated ESI probe
• Bruker Elute UHPLC, Intensity Solo C18 column
• Mobile phases: water and ACN each with 0.05% formic acid, 2 mM ammonium formate
• Gradient elution over 14 min, flow at 400 µL/min, injection 2 µL
• Data acquisition via Bruker MS Workstation and TASQ software

Main Results and Discussion

Validation demonstrated excellent linearity (R² > 0.99, RSD < 15%) across 5–100 ppb. Repeatability at 5 and 10 ppb showed RSDs of 2–7%, and recoveries ranged 80–102%. Signal-to-noise ratios at 5 µg/kg indicated sub-ppb detection limits. Full compliance with ISO 17025 and SANTE quality criteria was achieved for precision, accuracy, and sensitivity.

Benefits and Practical Applications

Key advantages of the method include:

• Minimal sample handling and rapid extraction
• Unattended, high-throughput analysis
• Sub-ppb detection capability for stringent residue monitoring
• Compatibility with routine food quality control and regulatory labs

Future Trends and Applications

Advances may include further miniaturization of sample prep, expansion to additional pesticide classes, and integration with automated data-processing platforms. Coupling this workflow with high-resolution MS or ambient ionization techniques could broaden screening capabilities for emerging contaminants.

Conclusion

An ultra-sensitive, fast, and robust LC-MS/MS method was established for fipronil and amitraz residues in eggs. Simple LLE and automated analysis meet regulatory requirements and support reliable food safety monitoring.

References

1. European Commission, SANTE/11945/2015
2. BBC News, 2017, "Fipronil in eggs"
3. NVWA, Dutch Food Safety Authority report
4. EURL Pesticides Data Pool
5. EU Pesticides Database
6. Commission Regulation (EU) No 1127/2014
7. Commission Regulation (EU) No 623/2017