Amino-bonded silica as stationary phase for liquid chromatographic determination of cyclopiazonic acid in fungal extracts

A new high-performance liquid (HPLC) chromatographic method is described for cyclopiazonic acid (CPA) determination in fungal cultures on a propylamino-bonded stationary phase with a CH3CN/CH3COONH4 buffer as mobile phase. Retention of CPA on propylamino modified silica under acidic conditions (protonated amino groups and deprotonated CPA) is governed by a mixed ion-exchange-reversed-phase mechanism. In addition to non-polar (hydrophobic) interactions, polar interactions with the surface silanols are also possible and become important as the polarity of the mobile phase decreases. A detection limit of 25 pg of CPA standard is obtained that represents an improvement of more than two orders of magnitude compared to existing HPLC procedures. UV-detector response was linear to 200 ng of CPA. Fungal extracts can be analysed after a simple dilution step with UV diode array detection that provides peak identity/purity assessment. The suitability of the proposed method as a rapid confirmatory test to assess the toxigenic potential of different Aspergillus and Penicillium strains is demonstrated by the analysis of 54 fungal extracts. (C) 2002 Elsevier Science B.V. All rights reserved.