2023 Volume 44 Issue 2 Pages 77-82
A sophisticated pretreatment method that combines solid-phase dispersive extraction (SPDE) and solid-phase fluorescence derivatization using immunoaffinity (IA) gel was developed to analyze aflatoxin M1 (AFM1) in cheese by liquid chromatography. Cheese samples were homogenized by adding acetonitrile/methanol/purified water mixture (6:1:3, v/v/v), followed by purification using SPDE. Trifluoroacetic acid was added to the IA gel for on-site solid-phase fluorescence derivatization. Recovery experiments (high concentration = 1 ng/g and low concentration = 0.1 ng/g) were performed. The limit of detection (S/N = 3) of AFM1 was 0.006 ng/mL, the limit of quantification (S/N > 10) was 0.02 ng/mL. The repeatability and intermediate precision were < 12% and < 14%, respectively, and the accuracy was 109–116%. For external accuracy control, the calculated HorRat values were less than 2 for both high- and low-concentration samples. A survey of 10 commercial cheeses was performed, and trace amounts of AFM1 were detected in cottage and mascarpone cheeses. In the proposed method, the validity, reliability, practicality, and robustness of the developed method were demonstrated. By using SPDE and solid-phase fluorescence derivatization in combination for AFM1 analysis, fluorescence derivatization during clean-up was realized, leading to simplification of the pretreatment operation.
