[Determinnation of nucleosides and nucleotides in milk powder by UPLC-MS/MS]

To establish a method for the determination of five nucleosides, including adenosine( A), guanosine( G), cytidine( C), uridine( U), inosine( I), and five nucleotides, including cytidine monophosphate( CMP), uridine monophosphate( UMP), adenosin monophosphate( AMP), inosine monphosphate( IMP), guanosine monophosphate( GMP), from milk powder products by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry( UPLCMS/MS).

After hydrolysis with warm water, the sample was deproteinated by25% acetic acid in water. The analysis was performed on a T3 column( 2. 1 mm × 100 mm, 1. 8 μm) and gradiently eluted using 0. 1% formic acid in both acetonitrile and water as the mobile phase. The samples were determined by mass spectrometry in the positive ion mode with the multiple reaction monitoring mode, quantified by the external standard method.

Five kinds of nucleosides and five kinds of nucleotides were separated within ten minutes. IMP and GMP were linear in the concentration range of 10-1000 ng/m L, and theother nucleosides and nucleotides were linear in the concentration range of 5-1000 ng/m L. The limits of detection for five nucleasides and nucleatides were in the range of 0. 002-0. 150 mg/kg. Recoveries of five nucleasides and nucleatides at different levels were in ranges of 89%-121%, with the relative standard deviations were in ranges of 0. 91%-8. 84%( n = 6).

This method is fast, accurate and sensitive and the preprocessing is simple, which can be used for determination of five nucleosides and five nuclestides in milk powder products effectively.