Determination of nitrofuran metabolite residues in shrimp by LC-MS/MS (ASMS)

Importance of Topic

Detection of nitrofuran metabolites in seafood is critical for ensuring consumer safety and regulatory compliance. Nitrofuran antibiotics have been banned in many countries due to their potential health risks. Highly sensitive analytical methods are required to monitor trace residues of their metabolites in shrimp and other aquatic products.

Study Objectives and Overview

This work describes the development and validation of a rapid LC-MS/MS method to quantify four nitrofuran metabolites (AOZ, AMOZ, AHD, SEM) in shrimp. The goal was to achieve low detection limits, high accuracy, and reproducible results suitable for routine screening and regulatory analysis.

Methodology and Instrumentation

Sample Preparation:

• 2 g shrimp homogenate spiked with internal standards
• Acidic hydrolysis and derivatization with 2-nitrobenzaldehyde at 37 °C for 16 h
• Neutralization, extraction with ethyl acetate, centrifugation and nitrogen evaporation
• Reconstitution in mobile phase and filtration (0.22 µm)

Chromatography:

• UHPLC: Nexera LC-40 with Shim-pack GISS C18 (100×2.1 mm, 1.9 µm)
• Mobile phase A: 0.002 M ammonium acetate; B: methanol; gradient from 10% to 95% B over 4 min and total run time of 8 min
• Flow rate 0.35 mL/min, column temperature 35 °C

Mass Spectrometry:

• Shimadzu LCMS-8045 triple quadrupole with ESI in positive MRM mode
• MRM transitions optimized for each metabolite and corresponding isotopic internal standards
• LabSolutions MRM Connect used for automated ion source parameter optimization

Main Results and Discussion

Calibration and Sensitivity:

• Linear response for 0.5–20 µg/L, correlation coefficients > 0.999
• Limits of detection between 0.06 and 0.11 ng/mL

Repeatability:

• Retention time RSD: 0.08–0.13%
• Peak area RSD: 0.89–9.28%

Recovery:

• Spiking at 1, 5 and 10 µg/kg in blank shrimp gave recoveries of 82.3–112.7% with RSD below 8.5%

Real Sample Analysis:

• No nitrofuran metabolites were detected in three commercial shrimp samples

Benefits and Practical Application

This method combines high throughput (8 min per run) with ppb-level sensitivity and robust quantitation. It is suitable for routine QA/QC in food safety laboratories and supports regulatory monitoring of banned nitrofuran residues in seafood.

Future Trends and Possibilities

Further developments may include:

• Extension to other seafood and complex food matrices
• Integration with high-resolution mass spectrometry for non-target screening
• Automated sample preparation and miniaturized platforms for field analysis
• Simultaneous multi-residue methods covering a broader range of veterinary drug metabolites

Conclusion

A sensitive, rapid and reliable LC-MS/MS method was established for four nitrofuran metabolites in shrimp. The approach offers excellent linearity, precision, accuracy and can be adopted by laboratories for compliance testing and consumer safety assurance.