[Determination of five nucleotides in infant formula milk powder by modified high performance liquid chromatography]

A modified high performance liquid chromatographic (HPLC) method was developed for the determination of the five nucleotides (uridine monophosphate (UMP), adenosine monophosphate (AMP), inosine monophosphate (IMP), guanosine monophosphate (GMP) and cytidine monophosphate (CMP)) in infant formula milk powder. The samples were extracted by water, deproteinized by acetic acid and purified with an HLB SPE cartridge. The analytes were separated by a Waters XBrigde Amide column (150 mm×4.6 mm, 3.5 μ m). Acetonitrile, 10 mmol/L sodium dihydrogen phosphate aqueous solution and 0.12%(v/v) phosphoric acid aqueous solution were used as mobile phases with gradient elution. The detection wavelength of photodiode array detector was set at 254 nm. Five linear calibration curves were obtained with correlation coefficients (r²) of 0.9999. The recoveries were determined at three spiked levels ranging from 86.9% to 105.7%. The limits of quantification (LOQs) were from 5.6 mg/kg to 8.0 mg/kg. The intra-day and inter-day precisions were 0.5%-1.7% (n=5) and 0.6%-1.9% (n=9), respectively. The method is simple, effective, accurate and repeatable. It is suitable for thedetermination of the five nucleotides in infant formula milk powder.