Comparison between the post-column derivatization with bromine by HPLC and the fluorometric analysis for determination of aflatoxins in medicinal herbs and plant extracts

AimTo compare the post-column derivatization technique (IAC-PCD-HPLC) for the determination of aflatoxins B₁, B₂, G₁ and G₂ and the rapid procedure with fluorometric analysis (SFB) for the determination of total aflatoxins. MethodsThe method of post-column derivatization with bromine by HPLC consisted of extraction of the sample with MeOH-H₂O (70∶30) followed by clean-up of the extracts with immunoaffinity columns and finally, HPLC determination with fluorescence detection. Aflatoxins B₁ and G₁ were determined as their bromine derivatives, produced in an on-line post-column derivatization system. In SFB method, samples were ground and extracted with methanol-water (70∶30). A portion of the extract was cleaned up by passage through a immunoaffinity column, One mL of purified extract was derivatized with a bromine reagent, and fluorescence of the solution was immediately quantified with a calibrated fluorometer containing a broad wavelength pulsed xenon light source. ResultsIn IAC-HPLC method, the overall average recoveries for three different medicinal herbs spiked at levels of 1.3 and 2.6 ng·g^-1 of total aflatoxins ranged from 93% to 97%. The detection limit was 0.06 μg·kg^-1 for both G₂ and B₂ and 0.20 μg·kg^-1 for both G₁ and B₁, based on a signal/noise 3∶1 and the precision (within-laboratory relative standard deviation) ranged from 0.8% to 1.4%. Each of aflatoxins B₁, B₂, G₁ and G₂ in 39 kind medicinal materials were determined by IAC-PCD-HPLC, and the total aflatoxins were determined by SFB. ConclusionThe SFB method is not the suitable method for the determination of total aflatoxins in medicinal herbs and plant extracts.