Determination of Ochratoxin A in Coffee via FREESTYLE ThermELUTE™ with Online HPLC-Measurement

Importance of the Topic

Ochratoxin A is a highly toxic fungal metabolite commonly found in coffee and other stored products. Regulatory limits set by the European Commission require sensitive and reliable methods to ensure food safety and compliance.

Objectives and Study Overview

This study describes an automated workflow combining FREESTYLE ThermELUTE™ immunoaffinity cleanup with online HPLC-fluorescence detection to quantify Ochratoxin A in coffee within 30 minutes per sample. The method aims to maximize throughput, precision, and sensitivity.

Methodology and Instrumentation

Samples were extracted, diluted, and filtered following OtaCLEAN SMART protocols. An aliquot in a 16 mL vial is processed by the FREESTYLE ThermELUTE system, which performs cleanup on OtaCLEAN SMART immunoaffinity columns and injects the eluate into the HPLC system automatically. Key instrumentation includes:

• FREESTYLE Basic and SPE modules
• FREESTYLE ThermELUTE™
• OtaCLEAN SMART immunoaffinity columns
• UltiMate™ 3000 RS fluorescence detector

HPLC conditions: RP C18 column; mobile phase acetonitrile/water/methanol (5/40/55, v/v/v) with 1% acetic acid; flow rate 0.6 mL/min; excitation at 335 nm and emission at 465 nm.

Main Results and Discussion

Recovery rates for spiked samples were consistently high: approximately 98% for chili, coffee, and paprika, 97% for beer, and 104% for rice at a 5 ppb spike level. Calibration was linear from 0 to 12.5 ppb (R² = 0.9992), with a limit of detection of 0.05 ppb (S/N = 5). Chromatograms demonstrated clear OTA peaks in both standard mixtures and a real contaminated coffee sample. A comparison with an external laboratory showed excellent agreement between methods.

Benefits and Practical Applications

The integrated system delivers rapid, unattended analysis, processing over 70 samples per day. It achieves precise quantification in the low ppt range, making it well suited for routine quality control and compliance testing in food laboratories.

Future Trends and Potential Uses

Upcoming developments may include coupling with mass spectrometry for multi-mycotoxin analysis, integrating IoT for remote monitoring, further miniaturization of sample preparation, and adaptation to additional contaminant classes.

Conclusion

The FREESTYLE ThermELUTE with online HPLC-FLD offers a robust, high-throughput approach to OTA determination in coffee, ensuring regulatory compliance and efficient laboratory operation.

References

• Commission Regulation (EU) No 105/2010 amending Regulation (EC) No 1881/2006 on maximum levels of Ochratoxin A in foodstuffs.
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