Liquid chromatographic determination of major secondary metabolites produced by Aspergillus species from section Flavi

A liquid chromatographic (LC) method was developed for simultaneous determination of major secondary metabolites-including cyclopiazonic acid (CPA), O-methylsterigmatocystin (OMST), and the versicolorins-produced by Aspergillus species from section Flavi (A. flavus, A. parasiticus, A. tamarii, and A. caelatus) on a liquid medium. Metabolites were extracted with chloroform and quantitated without prior cleanup by means of normal-phase ion-pair partition LC on silica gel with a mobile phase of n-heptane-2-propanol-n-butanol-water-tetrabutylammonium hydroxide (2560 + 900 + 230 + 32 + 8, v/v). Recoveries of CPA and OMST from fungal cultures spiked at 10 μg/mL were 98.90 ± 3.27 and 95.92 ± 5.27% (n = 5), respectively. At spike levels of 100 μg/mL, recoveries were 98.89 ± 3.87 and 97.65 ± 4.32% (n = 5), respectively. Limits of detection for pure standards were 0.25 μg/mL for CPA (at 280 nm) and 0.30 μg/mL for OMST (at 310 nm). UV detector responses to CPA and OMST were linear to about 0.5 and 3.5 μg/injection, respectively.