Quantitation of Mycotoxins in Four Food Matrices Comparing Stable Isotope Dilution Assay (SIDA) with Matrix Matched Calibration Methods by LC-MS/MS

Importance of the Topic

The occurrence of mycotoxins in agricultural products represents a major concern for public health and food industry economics. Mycotoxins such as aflatoxins, fumonisins, deoxynivalenol, ochratoxin A, HT-2 toxin, zearalenone and T-2 toxin can contaminate corn, wheat, peanuts and other commodities, leading to acute and chronic health effects in humans and animals. Accurate and reliable quantification methods are essential for regulatory compliance and risk management in food and feed analysis.

Objectives and Study Overview

This study compares the performance of stable isotope dilution assay (SIDA) versus matrix matched calibration for the quantitation of twelve mycotoxins across four food matrices: corn flour, peanut powder, brown rice flour and a corn/wheat mix. The main goals are to evaluate recovery, precision, linearity and the ability of each calibration approach to compensate for matrix effects inherent in electrospray ionization LC-MS/MS analysis.

Methodology

A streamlined “dilute-filter-shoot” sample preparation was employed. Homogenized samples (1 g) were extracted with water:acetonitrile (50:50 v/v), vortexed and centrifuged. The supernatant was filtered (0.2 µm PTFE), diluted and injected (5 µL) onto a biphenyl UHPLC column. A seven-minute gradient from 30% to 90% methanol (both phases containing 2 mM ammonium formate and 0.1% formic acid) was used for chromatographic separation.

Instrumentation Used

• UHPLC system: Shimadzu Nexera X2
• Mass spectrometer: Shimadzu LCMS-8060 in positive ESI mode
• Analytical column: Raptor Biphenyl 2.7 µm, 50 mm × 2.1 mm

Main Results and Discussion

The method achieved baseline separation of all 12 analytes in 5.5 minutes, including isobaric fumonisins B2 and B3. Matrix matched calibration recoveries varied widely (27.7%–204%) with RSDs below 11%, reflecting inconsistent extraction efficiencies and matrix interferences, notably for T-2 toxin in peanut powder. In contrast, SIDA demonstrated excellent linearity (r2 ≥ 0.9996) over a 1000-fold concentration range and average accuracies between 91.4% and 98.6% (RSDs 2%–7%). Analysis of Fapas reference materials confirmed the robustness of SIDA, while non-matched internal standards yielded unacceptable biases for analytes lacking labeled analogues.

Benefits and Practical Applications

The SIDA approach provides superior compensation for ion suppression/enhancement and enables reliable quantification of mycotoxins in diverse, complex matrices. Laboratories requiring routine, high-throughput screening can adopt this method for regulatory compliance and quality control. Matrix matched calibration remains a viable alternative when isotopic standards are unavailable, but demands careful validation for incurred toxins and potential co-eluting interferences.

Future Trends and Potential Applications

• Broader adoption of uniformly labeled internal standards to extend SIDA to additional mycotoxins and emerging contaminants.
• Integration of ultrafast UHPLC and high-resolution MS to expand analyte coverage and throughput.
• Development of automated, miniaturized sample preparation platforms for on-site or field testing.
• Application of chemometric and machine learning tools to predict matrix effects and optimize calibration strategies.

Conclusion

This work demonstrates that SIDA outperforms matrix matched calibration in precision, accuracy and resilience to matrix effects for the quantitation of twelve mycotoxins in four food matrices. The rapid LC-MS/MS workflow supports effective monitoring in food safety laboratories. Where isotopic standards are not accessible, matrix matched calibration serves as an alternative but may not fully correct for all matrix-induced variabilities.

References

No formal literature references were provided in the source document.