A High Sensitivity LC/MS/MS Method with QuEChERS Sample Pre-treatment for Analysis of Aflatoxins in Milk Powder Samples

Importance of the Topic

Aflatoxins are carcinogenic mycotoxins produced by Aspergillus species that can contaminate animal feed and dairy products. Their detection in milk powder is critical due to strict regulatory limits and potential health hazards.

Objectives and Study Overview

The study aimed to establish a high sensitivity LC/MS/MS method with QuEChERS sample pre-treatment for simultaneous quantification of aflatoxins B1, B2, G1, G2 and M1 in milk powder. The goal was to achieve rapid analysis with improved cost efficiency compared to immunoaffinity cleanup.

Methodology and Instrumentation

• Sample preparation followed a modified QuEChERS protocol using 2 g milk powder extracted with acetonitrile/water (3:1) containing 0.1% formic acid, degreased with hexane and cleaned by dSPE (MgSO4, PSA, C18).
• Extracts were evaporated under nitrogen and reconstituted in water/methanol (95:5) before injection.

Used Instrumentation

• Shimadzu LCMS-8060 triple quadrupole mass spectrometer with heated electrospray ionization interface.
• Kinetex C18 column (2.1 × 100 mm, 1.7 µm) with gradient elution of aqueous ammonium acetate/formic acid and methanol ammonium acetate.

Results and Discussion

• All five aflatoxins were baseline separated within 7.5 min with linear calibration (r2 > 0.999).
• Limits of detection and quantitation were below 0.83 pg/mL and 2.50 pg/mL respectively.
• Method repeatability showed RSD values below 7.5% and recoveries ranged from 70% to 88%.
• Matrix effects in milk powder were minimal (approximately 105–116%).
• Analysis of commercial milk powder samples revealed no detectable aflatoxins.

Benefits and Practical Applications

• High analytical sensitivity suitable for compliance with stringent regulatory limits.
• Cost and time savings due to simplified QuEChERS cleanup versus immunoaffinity columns.
• Suitable for routine quality control in food safety laboratories.

Future Trends and Opportunities

• Automation of QuEChERS workflows and online sample cleanup integration with LC/MS/MS.
• Expansion to multi-mycotoxin screening using high-resolution mass spectrometry.
• Development of portable and miniaturized platforms for on-site monitoring.

Conclusion

The proposed LC/MS/MS method combined with QuEChERS sample preparation offers a robust, sensitive and cost-effective approach for accurate quantification of aflatoxins in milk powder, meeting regulatory requirements and supporting food safety monitoring.

References

• Iqbal SZ Jinap S Pirouz AA Ahmad Faizal AR Trends in Food Science Technology 2015 46 110 119
• Cherkani-Hassani A Mojemmi B Mouane N Trends in Food Science Technology 2016 50 56 69