Use of rice husk as an adsorbent for performing MSPS technique for determining the aflatoxins occurrence in onion

Abstract

The simultaneous determination of aflatoxins (AFLA) B1, B2, G1 and G2 was investigated in onions by means of matrix solid-phase dispersion (MSPD) extraction methodology, and using rice husk as adsorbent element. The AFLA identification and quantification were carried out by using high efficiency thin layer chromatography (HPTLC) and high efficiency liquid chromatography coupled to a fluorescence detector (HPLC-FD). The best adsorbent was the compound constituted by the rice husk:celite mixture (1:1) in a 1:1 ratio with the mass of the sample, and employing the mixture chloroform:methanol (5:25) as eluent. The methodology showed the limit of detection ranging from 0.05 to 1 μg.kg-1, and of the accuracy from 78 to 93%; and variation coefficients ranged from 11 to 14%. After being validated, the methodology was tested on its applicability in determining the aflatoxins occurrence in onion samples, which were classified according to the standard MAPA. Aflatoxin contamination was found in 43% of analyzed samples with a maximum content of 90 μg.kg-1 of AFLAB2.