Abstract: Nicotinamide ribosome (NR), nicotinamide mononucleotide (NMN), nicotinic acid (NA) and nicotinamide (NAM) are 4 precursor compounds of NAD⁺, which can be converted to NAD⁺ in vivo to work after oral administration. This study established a method for simultaneous determination of NAD⁺ and its four precursors in tea by ultra-high performance liquid chromatography-tandem mass spectrometry. The tea samples were extracted by water, then diluted and directly analyzed by UPLC-MS/MS. Method validation shows this method has good linearity in their respective range with correlation coefficients (R²) higher than 0.99. The average recoveries ranged from 70.00 % to 120.00% with relative standard deviations (RSDs) of 2.09%-14.50%. The limits of quantitation (LOQs) were 0.10-0.50 μg·L^-1. The determination results of five target compounds in green tea, black tea and dark tea show that green tea and black tea were the good natural food sources of NR, NMN, NAD⁺. The results of principal component analysis show that the contents of five compounds could well distinguish black tea, green tea and dark tea. The cluster analysis shows the same type of tea from the same origin was of uneven quality, with high dispersion in samples, and it was difficult to identify each other.

Key words: tea, nicotinamideadenine dinucleotide (NAD⁺), nicotinamide nononucleotide (NMN), nicotinamide riboside (NR), UPLC-MS/MS