Report on the inter-laboratory comparison organised by the European Union Reference Laboratory for Mycotoxins for the validation of a method for the determination of Ochratoxin A in liquorice roots and extracts - Method based on immunoaffinity column clean-up with high performance liquid chromatography and fluorimetric detection method

摘要

The European Union Reference Laboratory for Mycotoxins (EU-RL Mycotoxins), operated by the Institute for Reference Materials and Methods (IRMM) of the Joint Research Centre (JRC), organised a method validation study (MVS) for evaluating the effectiveness of a method for the determination of Ochratoxin A (OTA) in liquorice root and liquorice extracts. A test portion is extracted with a mixture of methanol and aqueous sodium bicarbonate solution. The extract is filtered, diluted with phosphate buffered saline (PBS), and OTA is purified with an immunoaffinity column containing antibodies specific to OTA. The purified extract is dried, reconstituted and quantified by high performance liquid chromatography-flourimetric detection.Twenty laboratories from 13 EU Member States, a laboratory in Uruguay, one in Turkey, one in Canada, and one in US participated in this study. Contents of OTA ranged from 26 to 141 µg/kg and from 8 to 52 µg/kg for liquorice extracts and root material respectively. Mean recoveries were calculated as 87 % for liquorice root, and 84 to 88 % for liquorice extracts.Based on results for the spiked and naturally contaminated samples the relative standard deviations for reproducibility (RSDR) ranged from 10 to 17 % and from 11 to 22 % in liquorice extracts and liquorice root respectively. Standard deviations for repeatability (RSDr) ranged from 4 to 9 % and from 6 to 9 % in liquorice extracts and liquorice root respectively. The Commission Regulation (EC) No 401/2006 lays down performance criteria that must be met by a method to determine OTA in food when used for official control purposes. These criteria have been met by this method for both the liquorice root and the liquorice extracts.