Simple and Rapid Screening of Melamine in Milk Products with High Resolution Accurate Mass Benchtop Orbitrap LC/MS

摘要

1) The high resolution, accurate mass Exactive mass spectrometer is shown to be sensitive in detecting <0.1 ppb melamine (0.5 pg on column) in neat standard and response is linear from 0.1 to 100 ppb. The error for mass accuracy is <2-3 ppm with lock mass. 2) Milk samples prepared by dilute-and-shoot have shown severe ion suppression that has been reduced with a simple and rapid HILIC LC separation (1 minute run), after which a consistent response factor of 0.3-0.5 for each sample matrix can be used for quantitation. 3) Quantitation limits are less than 44, 65, and 110 ppb for coffee cream, infant formula and 3-in-1 instant coffee mix, respectively, exceeding the requirements of 100-250 ppb LOQ such as by US FDA (250 ppb in infant formula).