Sensitive Femtogram Determination of Aflatoxins B1, B2, G1 and G2 in Food Matrices using Triple Quadrupole LC/MS - Yang Chen and Jack Cappozzo

A simple and inexpensive sample cleanup procedure based on a dispersive solid phase adsorption approach (C18) is effective in removing background matrix contaminants for reliable determination of aflatoxins in food at the femtogram level by triple quadrupole LC/MS. This application demonstrates fast analysis time (< 6 min) with good chromatographic resolution and separation for all four aflatoxins. Standard curves for each aflatoxin analyte show good linearity (> 0.998) across a wide concentration range (0.1–100 μg/L). Recoveries using the dispersive solid phase adsorption approach were between 85–110% for each aflatoxin for all four spiked food matrices and were comparable to other widely used SPE routines. The limit of detection was determined to be < 0.15 μg/kg and the limit of quantitation < 0.5 μg/kg for all four sample matrices. Precision data was typically below 5% RSD for all analytes.

Introduction
Aflatoxins are a group of mycotoxins produced as metabolites by the fungi aspergillus flavus and aspergillus parasiticus [1]. They can be found in various foods including grains, nuts, and spices [2]. There are four major naturally occurring aflatoxins: B1, B2, G1 and G2 (Figure 1). Exposure to them can cause cancer in humans and live stock, therefore reliable and sensitive analytical methods for the determination of aflatoxins are required to safeguard our food supply.

Experimental
These analyses were performed using an Agilent G6460A Triple Quadrupole LC/MS/MS System equipped with Agilent Jet Stream Technology [3] using an Agilent 1200 Series SL LC. The LC system consisted of a binary pump (G1312B), vacuum degasser (G1379B), a low carryover automatic liquid sampler (G1367D), thermostatted column compartment (G1316B) and MassHunter data system.

Aflatoxin standards and foods
Purified aflatoxin standards (B1, B2, G1 and G2) were obtained from Sigma-Aldrich. Aflatoxin-free corn flour, wheat, peanut and walnut samples obtained from a local grocery store were used for recovery studies.