New method of citrinin determination by HPLC after polyamide column clean-up

In the past, various analytical methods of citrinin determination have been published; their application is not unproblematic. In this article, a HPLC method for sensitive fluorescence detection, based on solid phase extraction in combination with a HPLC gradient, is described. The samples are extracted with dichloromethane with the addition of phosphoric acid, and the extract is cleaned up on polyamide columns. According to this method, citrinin is detectable in cereals and milling products up to a detection limit of similar to1-2 mug/kg (limit of quantification: 3-5 mug/kg). The mean recovery rates amounted to 74-90%. Analyses of some samples containing ochratoxin A (OTA) show that citrinin is especially detectable in cereal products, such as brans, wheatings and shorts, which contain increased amounts of the outer layers of the kernel. Citrinin, as well as OTA, was also detected in cocoa shells and raisins. 14 OTA-containing samples had citrinin contents of 1-8 mug/kg. Further, it was demonstrated that the new method is also applicable for citrinin determination in red-fermented rice.