Determination of aflatoxin M-1 in milk and dairy products using high performance liquid chromatography-fluorescence with post column photochemical derivatization

摘要

The determination of aflatoxin M-1 in milk using high performance liquid chromatography with photochemical post-column derivatization and fluorescence detection is described. The samples were first extracted and clean-up using the immunoaffinity AFLATEST column originally targeted for aflatoxins B-1, B-2, G(1) and G(2). The separation of aflatoxin M-1 were performed using C18 Hypersil gold (150 mm x 4.6 mm, 511,mu m) column at 40 degrees C under isocratic elution. Fluorescence detector (FLD) was set at 360 nm and 440 nm as excitation and emission, respectively. The use of methanol to replace acetonitrile as the mobile phase resulted in similar to 67% peak area enhancement of AFM(1). The limit of detection (LOD) and quantification (LOQ) of the analytical method after post-column derivatization without evaporation/reconstitution with mobile phase was 0.0085 mu gL(-1) and 0.025 mu gL(-1) respectively. However, LOD and LOQ improved to 0.002 and 0.004 mu gL(-1) respectively with the addition of evaporation/reconstitution step. The method was statistically validated, showing linear response (R-2 > 0.999), good recoveries (85.2-107.0%) and relative standard deviations (RSD) were found to be <= 7%. The proposed method was applied to determine AFM(1) contamination in various types of milk and milk products. Only 2 samples were contaminated with aflatoxin M-1 (10% incidence). However, the contamination level is below the Malaysian and European legislation limits. (C) 2017 Elsevier B.V. All rights reserved.