Assay of ochratoxin A in wine and beer by high-pressure liquid chromatography photodiode array and gas chromatography mass selective detection

To routinely assay the concentrations of ochratoxin A (OTA) in wines and beers, two new methods were developed and evaluated. The first utilized solid-phase extraction on a C-18 cartridge to achieve a 100-fold sample concentration followed by high-performance liquid chromatography on a Cls column with gradient elution and quantitation at 333 nm by means of a photodiode array detector. Positive confirmation can be carried out by purity and match-factor analysis as well as peak shift following esterification with BF3. Total run time is 28 min. The limits of detection (LOD) and quantitation (LOQ) are 0.05 and 0.10 mug/L, respectively. Recovery and imprecision-ranged from 83 to 94% and from 4.0 to 8.9%, respectively. With a throughput of 35 assays per working day, this method is ideal for routine OTA analysis. It was used to survey the concentrations of OTA in 942 wines (2 of which gave values between 0.1 and 0.2 mug/L) and 107 beers (2 of which gave values between 0.05 and 0.1 mug/L): OTA was detected more frequently in red than white wines, with the highest incidence in red wines from Spain and Argentina. There was no association between OTA and country of origin or beverage type among the beers analyzed. The second method utilized gas chromatography with mass selective detection monitoring eight specific ions, preceded by extraction in dichloromethane and derivatization with bis[trimethylsilyl]trifluoroacetamide. LOD and LOQ were 0.1 and 2 mug/L, respectively; recovery and imprecision were 69-75 and 9.0-11.1%, respectively. The method is not suitable for routine quantitation but is potentially useful as a confirmatory tool:for samples with OTA greater than or equal to0.1 mug/L.