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 be ers, two new methods were developed and evaluated. The first utilized solid -phase extraction on a C-18 cartridge to achieve a 100-fold sample concentr ation followed by high-performance liquid chromatography on a Cls column wi th gradient elution and quantitation at 333 nm by means of a photodiode arr ay detector. Positive confirmation can be carried out by purity and match-f actor analysis as well as peak shift following esterification with BF3. Tot al 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 fro m 83 to 94% and from 4.0 to 8.9%, respectively. With a throughput of 35 ass ays 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 valu es 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 wi nes, with the highest incidence in red wines from Spain and Argentina. Ther e was no association between OTA and country of origin or beverage type amo ng the beers analyzed. The second method utilized gas chromatography with m ass selective detection monitoring eight specific ions, preceded by extract ion in dichloromethane and derivatization with bis[trimethylsilyl]trifluoro acetamide. LOD and LOQ were 0.1 and 2 mug/L, respectively; recovery and imp recision 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.