Rapid and Quantitative Analysis of Aflatoxin M1 From Milk Using Atmospheric Pressure - Matrix Assisted Laser Desorption/Ionization (AP-MALDI)-Triple Quadrupole Selected Reaction Monitoring

Background: Aflatoxin M1 (AFM1) is a carcinogenic hydroxylated metabolite commonly found in milk. It is relatively stable toward decontamination procedures posing a major health risk, and it requires an international regulatory mandate of detection at trace levels. Objective: To develop a high-throughput, reliable, and compliant method for the identification of AFM1 in milk samples using atmospheric pressure - matrix assisted laser desorption/ionization (AP-MALDI) selected reaction monitoring (SRM) quantitation. Method: The milk sample was diluted in water and cleaned with immunoaffinity chromatography (IAC), followed by analysis using AP-MALDI hyphenated with a triple quadrupole mass spectrometer for SRM. Results: A fast and reliable AP-MALDI SRM quantitative method was developed for the determination of AFM1 with analysis time of 1 min per sample. The diagnostic product ions of AFM1 at 273.1 u and 229.2 u were monitored during the SRM. The calibration curves yielded excellent linearity (R2 = 0.99) with good recoveries for quality control samples (97-106%). The ion ratios of the qualifier to quantifier displayed excellent RSD (1-7.8%) for n = 3. Conclusions: The developed method provided rapid quantification for AFM1. The fast AP-MALDI SRM method can allow analysis of AFM1 in a large number of milk samples. Given the time required for analysis, cost-effectiveness, and superior analytical performance, this method can be adopted in commercial food testing laboratories. Highlights: Aflatoxins (AF) are a major health risk. Speedy analysis of large sample sizes from food is a risk mitigation strategy but remains an unmet need. Quantitative, chromatography-free, and internal standard-free AP-MALDI SRM based analysis of AF is a high-throughput and cost-efficient alternative. Satisfactory performance was achieved for quantitative AP-MALDI SRM analysis of AFM1 in milk subsequent to a simple sample clean-up step.