Solid Phase Extraction and SFC-MS/MS Method for Analysis of Aflatoxins M1, M2, B1, B2, G1 and G2 in Milk Powders

Aflatoxins B1, B2, G1 and G2 are secondary metabolites that are produced by Aspergillus fungi. If aflatoxins B1 and B2 are present in feeds consumed by lactating animals, they can be converted to hydroxylated metabolite aflatoxins M1 and M2 in the animals respectively, which are found eventually in the milk [1]. Aflatoxins B1, B2, G1, G2 are carcinogenic and aflatoxin M1 is potentially carcinogenic. The levels of these aflatoxins in dairy products like milk powders are strictly regulated around the world. For example, European Union regulation limits aflatoxin M1 in milk below 0.050 μg/kg [2]. Many LC/MS/MS methods were reported for analysis of aflatoxins B1, B2, G1, G2 and M1, but few including aflatoxin M2 [4]. In addition, sample preparation method is varied for different matrixes and is often a critical factor to the analysis sensitivity and accuracy. The aim of this study is to develop a novel method - supercritical fluid chromatography SFC-MS/MS for high sensitivity analysis of aflatoxins B1, B2, G1, G2, M1 and M2 in milk powders. The supercritical fluid (SF) CO2 mobile phase has advantages of cost-effective and environmental friendly as compared to organic solvents. A special sample preparation procedure was explored, which involved extraction with adding Q-Sep extract salt and purification with Supel? Tox Alfazea SPE cartridge. Conventional SPE uses the concept of binding target compounds to the stationary phase first and eluted out by organic eluent subsequently. However, Supel? Tox Alfazea SPE cartridge acts as a filter where the sample matrix is trapped while the target aflatoxins are eluted out.