Determination of Ochratoxin A in wine by packed in-tube solid phase microextraction followed by high performance liquid chromatography coupled to tandem mass spectrometry

- An in-tube SPME method was developed for the determination of Ochratoxin A in wine.
- The in-tube SPME method was optimized using a central composite design.
- Acetonitrile percentage and sample load time were investigated and optimized.
- The proposed method was validated according to international guidelines.
- The validated method was useful for determination of OTA in wine samples.

Ochratoxin A (OTA), a widely studied mycotoxin, can be found in a variety of food matrices. As its concentration in food is generally low (in the order of μg kg−1), sample preparation techniques are necessary for the analyte purification and pre-concentration in order to achieve the required low detection limits. The separation and detection methods used for OTA analysis should also offer proper sensitivity in order to allow the adequate quantification of the analyte. This manuscript addresses the development of a methodology aiming the analysis of OTA in wine samples by packed in-tube SPME in flow through extraction mode coupled to HPLC-MS/MS. The in-tube SPME set up utilized a PEEK tube packed with C18 particles as the extraction column. The method was optimized by a central composite design 22 + 3 extra central points, having as factors the percentage of ACN and time in the sample load step. The functionalities of the method were attested and its analytical conditions, enhanced by using 22% of ACN and 6 min in the sample load step. Validation of the method was also accomplished prior to analyses of both dry red wine and dry white wine samples. The method demonstrated proper sensitivity, with detection and quantification limits equal to 0.02 and 0.05 μg L−1, respectively. Linearity and precision exhibited a 0.996 correlation coefficient and RSD under 6%, respectively. The method proved to be accurate at medium and higher concentration levels with a maximum recovery of 73% at higher concentration levels. OTA was not detected in either dry red and dry white wine samples evaluated in this work. If present, it would be at concentrations lower than the detection and quantification limits established for the proposed method, and considered not a potential danger to human health according to our present knowledge.