Quantification of Mycotoxins in Animal Milk from India (FS14-04-19)

Abstract

Objectives: Animal milk can be contaminated with mycotoxins (secondary metabolites of fungi) through poor quality feed and may be a source of human exposure. Our objective was to develop and optimize a method to detect biologically relevant concentrations of 8 mycotoxins (Aflatoxins B1, B2, G1, G2, M1, M2; Ochratoxins A, B) in animal milk. Methods: We used ultra-high performance liquid chromatogra-phy/tandem mass spectrometry using selected reaction monitoring (UHPLC/MS-SRM) to quantify mycotoxins in animal milk samples (total N = 38; n = 10 each from cow and commercial milk and n = 9 from buffalo and goat) from the southern Indian states of Karnataka and Tamil Nadu. Method development was conducted and stable isotope dilution employed, using AFB1-D3 for aflatoxins and OTA-D5 for ochratoxins. We validated the method and examined matrix effects, freeze-thaw and auto-sampler stability. Our dynamic ranges from quantification were between 7.8-5000 pg/mL. Results: Among samples collected from Southern India, 8 of 10 cow [median 103.35 pg/mL; n = 3 > 500 pg/mL]; 0 of 9 buffalo and 10 of 10 commercial [median: 151.5 pg/mL], milk samples were above the LOQ. AFM2 was also seen in samples from both regions, but in lower quantities when compared to AFM1 [median (north): 25.8 pg/mL; median (south): 70.95 pg/mL]. All except 3 samples were below the LOQ (31.3 pg/mL) for OTA, however we detected a sodium adduct of OTA above LOQ, across samples. We found [Na-OTA] in goat milk [median: 5.9 ng/ mL] > buffalo [median: 2.2 ng/mL] > commercial [median: 2.04 ng/ mL] > cow [median: 0.8 ng/mL]. Other mycotoxins were seen in concentrations close to or below LOQ. We did not identify significant stability issues. Conclusions: We developed a highly sensitive method with biologically relevant dynamic ranges for detection of mycotoxins in milk samples. We found AFM1, AFM2, and Na-OTA in milk samples from Southern India. Further studies with larger sample sizes are warranted to establish the extent of mycotoxin contamination in milk.