Determining aflatoxins B1, B2, G1 and G2 in maize using florisil clean up with thin layer chromatography and visual and densitometric quantification

Abstract

1 Recebido para publicação em 25/01/00. Aceito para publicação em 07/05/01. 2 ministério da agricultura e do abastecimento -laboratório de controle de qualidade e segurança alimentar/LAV/MG. SUMMARY A method for determining aflatoxins B 1 (AFB 1), B 2 (AFB 2),G 1 (AFG 1) andG 2 (AFG 2) in maize with florisil clean up was optimised aiming at one-dimensional thin layer chromatography (TLC) analysis with visual and densitometric quantification. Aflatoxins were extracted with chloroform: water (30:1, v/v), purified through florisil cartridges, separated on TLC plate, detected and quantified by visual and densitometric analysis. The in-house method performance characteristics were determined by using spiked, naturally contaminated maize samples, and certified reference material. The mean recoveries for aflatoxins were 94.2, 81.9, 93.5 and 97.3% in the range of 1.0 to 242 µg/kg for AFB 1 , 0.3 to 85mg/kg for AFB 2 , 0.6 to 148mg/kg for AFG 1 and 0.6 to 140mg/kg for AFG 2 , respectively. The correlation values between visual and densitometric analysis for spiked samples were higher than 0.99 for AFB 1 , AFB 2 , AFG 1 and 0.98 for AFG 2 . The mean relative standard deviations (RSD) for spiked samples were 16.2, 20.6, 12.8 and 16.9% for AFB 1 , AFB 2 , AFG 1 and AFG 2 , respectively. The RSD of the method for naturally contaminated sample (n = 5) was 16.8% for AFB 1 and 27.2% for AFB 2 . The limits of detection of the method (LD) were 0.2, 0.1, 0.1 and 0.1mg/kg and the limits of quantification (LQ) were 1.0, 0.3, 0.6 and 0.6mg/kg for AFB 1 , AFB 2 , AFG 1 and AFG 2 , respectively. (218 words)