One-year monitoring of aflatoxins and ochratoxin A in tiger-nuts and their beverages.

A sensitive and selective liquid chromatography-triple quadrupole-tandem mass spectrometry (LC-ESI-MS-MS) method was developed for the routine analysis of aflatoxins (AFB(1), AFB(2), AFG(1) and AFG(2)) and ochratoxin A (OTA) in tiger nuts and tiger-nut beverage (horchata). A matrix solid phase dispersion was adapted to eliminate lipidic interferences. The solid support was C(18), while the elution solvent was acetonitrile. Mean recoveries obtained at two fortification levels were 72-83% and 71-81% for horchata and tiger nut respectively with relative standard deviations (RSDs) <13% and 15% respectively. The LC-MS-MS method allowed quantification and identification at low levels in two matrices. The method was applied for the routine analysis of tiger-nuts and horchata samples collected from different supermarkets of Valencia (Spain) during one year (March 2009-March 2010). A total of 238 samples were analysed and 32 samples were found positives for OTA, AFB(1), AFB(2) and AFG(2).