Rapid Quantitation and Confirmation of Aflatoxins in Corn and Peanut Butter, Using a Disposable Silica Gel Column, Thin Layer Chromatography, and Gas Chromatography/Mass Spectrometry

Abstract

Asimple, rapid, and solvent-efficient method for determining aflatoxins in corn and peanut butter is described. Aflatoxins B1, B2, G1, and G2 were extracted from SO g sample with 200 mL methanol-water (85 + 15). A portion of the extract was diluted with 10% NaCl solution to a final concentration of 50% methanol, and then defatted with hexane. The aflatoxins were partitioned into chloroform. The chloroform solution was evaporated, and the residue was placed on a 0.5 g disposable silica gel column. The column was washed with 3 mL each of hexane, ethyl ether, and methylene chloride. Aflatoxins were eluted with 6 mL chloroform-acetone (9 + 1). The solvent was removed by evaporation on a steam bath, and the aflatoxins were determined using thin layer chromatography (TLC) with silica gel plates and a chloroform-acetone (9 + 1) developing solvent. Overall average recovery of aflatoxin B] from corn was 82%, and the limit of determination was 2 ng/g. For mass spectrometric (MS) confirmation, aflatoxin B1, in the extract from 3 g sample (20 ng/g) was purified by TLC and applied by direct oncolumn injection at 40°C into a 6 m fused silica capillary gas chromatographic column. The column was connected directly to the ion source. After injection, the temperature was rapidly raised to 250¯C, and the purified extract was analyzed by negative ion chemical ionization MS.

Deciphering drought‐induced metabolic responses and regulation in developing maize kernels

“…Inoculated ears with or without drought treatments were collected at 60 DAP for use in aflatoxin analysis and quantification. Aflatoxin extraction and analysis were conducted according to Guo et al (1996) using thin-layer chromatography (TLC; Park et al, 1994;Robertson et al, 1967;Trucksess et al, 1984). The aflatoxin standards were purchased from Sigma-Aldrich (St. Louis, MO), and all the samples were analysed in three replicates.…”

Methods for Detection of Aflatoxins in Agricultural Food Crops

“…Different analytes, depending on their molecular structures and interaction with the stationary and mobile phases, either adhere to the stationary phase more or remain in the mobile phase, thereby allowing for quick and effective separation. Thin-layer chromatography has been widely used in the determination of aflatoxins in different foods [59][60][61] and as low as 1-20 ppb of aflatoxins has been reported [62]. The advantage of using the TLC method is that it can detect several types of mycotoxins in single test sample [30,62].…”

Aflatoxins isolated by immunoaffinity chromatography from foods consumed in the Gambia, West Africa

“…The development of methods to assess human exposure to environmental carcinogens requires techniques that are sensitive, specific, and amenable to large numbers of samples. For example, the chromatographic methods [Trucksess et al, 1984;Groopman and Donahue, 19881 have the power to resolve mixtures of aflatoxins into the individual components, providing that the extraction procedure does not introduce high levels of interfering compounds. The antibody-based methods [e.g., Chu et al, 19871 are more specific and selective than straightforward chromatography but immunoassays are compromised by the intrinsic cross-reactivity of an antibody for multiple aflatoxins.…”

“…Many analytical methods exist for the measurement of aflatoxins in food. These techniques include chromatography following extraction with solvent, such as the minicolumn, thin-layer chromatography and high-pressure liquid chromatography (HPLC) [Trucksess et al, 1984;Groopman and Donahue, 19881, and immunological assays using specific antibodies or antisera, such as enzyme-linked immunosorbent assays and radioimmunoassays [Trucksess et al, 1989;Chu et al, 19871. 0 1992 Wiley-Liss, Inc Each method has unique characteristics with respect to specificity and sensitivity; some methods are adequate only for qualitative analysis and some are quantitative. A major problem in measuring trace amounts of aflatoxins in a food is the lack of selectivity of extraction with solvents.…”