Evaluation of analytical assays efficiency to detect aflatoxin M<inf>1</inf> in milk from selected areas in Egypt and South Africa
Department of Animal Health, Faculty of Agriculture and Technology, North West University, Mafikeng Campus, Private Bag X2046, Mmabatho, South Africa; Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut, Egypt; College of Applied Medical Sciences, Medical laboratories Department, Majmaah University, Saudi Arabia; Chemistry Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut, Egypt
Recently, methods to analyze aflatoxin M<inf>1</inf> (AFM<inf>1</inf>) in milk and dairy products have been developed for both screening purposes (i.e., rapid, economical, and simple methods) and for confirmation by accurate, reproducible, and sensitive quantification. The aim of this study was to evaluate the efficiency of different rapid kits and techniques available on the market by using different analytical methods: thin layer chromatography (TLC), immunoaffinity column, AFM<inf>1</inf> immunochromatographic strip, and ELISA; some samples were also submitted to HPLC for comparison of results. One hundred thirty-eight samples were collected from rural subsistence and commercial dairy farms in selected areas of Egypt and South Africa and analyzed for the presence of AFM<inf>1</inf>. The results obtained by AFM<inf>1</inf> immunochromatographic strip indicated the lowest frequency of occurrence, with a detection incidence of 20.45% in Egyptian samples and 16% in South African samples. Aflatoxin M<inf>1</inf> was detected by ELISA in 65 (73.9%) Egyptian milk samples, with a range of 8.52 to 78.06 ng/L, and in 34 (68%) South African milk samples, with a range of 5 to 120 ng/L. A higher incidence of AFM<inf>1</inf> in Egyptian milk samples was shown by TLC (81.8%) compared with ELISA (73.9%). Samples analyzed by ELISA in South African milk samples demonstrated satisfactory correlation when compared with HPLC coupled with Coring cell (an electrochemical cell for the derivatization of AFM<inf>1</inf>). Among the positive samples, 18 of the Egyptian samples (20.45%) positive by ELISA had levels of AFM<inf>1</inf> above the European Union (EU) regulatory limit (50 ng/L), whereas 65 samples (73.9%) were above the Egyptian regulatory limit (0 ng/L). Six of the South African samples (12%) tested by ELISA were above the South African (50 ng/L) and EU regulatory limits. The mean concentration of AFM<inf>1</inf> was 25.79 ng/L in Egyptian samples and 17.06 ng/L by ELISA and 39 ng/L by HPLC in South African samples. These contamination levels would not represent a serious public health hazard according to EU legislation. © 2015 American Dairy Science Association.