Detection of a Novel Metabolite of Urea in Soil by Extractive Electrospray Ionization Mass Spectrometry

As an important nitrogen(N) source for the growth of many organisms, urea is intensively used as a nitrogen fertilizer. A better understanding of urea metabolism is required. Using extractive electrospray ionization tandem mass spectrometry(EESI-MSn), a new urea metabolite (3,3-diamino-3-hydroxypropanoic acid) was detected in soil extracts from the rhizosphere of Pinus massoniana. A 3, 3-diamino-3-hydroxypropanoic acid standard was synthesized from urea, sodium acetate and lithium tert-butoxide. The protonated molecular ion and the sodium adduct were observed in the mass spectrum. With tandem mass spectrometry, the two signals from the synthetic sample were quickly identified and verified the protonated molecular ion from the soil extracts. It can be inferred that 3,3-diamino-3-hydroxypropanoic acid is a metabolite from urea in soil, and this study provides clues for future research of nitrogen transformation processes in urea fertilized soils. EESI-MS is a promising tool for the rapid and accurate identification of trace levels of short-lived metabolites.