The high resolution, accurate mass Exactive mass spectrometer was 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 ppm with lock mass. Milk samples prepared by dilute-and-shoot showed severe ion suppression that was reduced with a simple 1-minute isocratic HILIC LC separation, after which a consistent response factor of 0.3-0.5 for each sample matrix was obtained for quantitation. Quantitation limits were less than 44, 65, and 110 ppb for coffee cream, infant formula and 3-in-1 instant coffee mix, respectively, exceeding the requirement of 250 ppb LOQ as stated by US FDA for infant formula. 賽默飛Q Exactive Plus LCMS 系統(tǒng)