土壤中一种新的尿素衍生物的电喷雾萃取电离质谱分析

采用电喷雾萃取电离串联质谱(EESI-MSⁿ)技术直接分析马尾松根际土壤溶液, 发现了一种不稳定的尿素衍生物3,3-二氨基-3-羟基丙酸. 为确证其结构, 以尿素为原料合成了该衍生物, 并采用EESI-MSⁿ分析合成产物. 结果表明, 合成产物与土壤溶液中的3,3-二氨基-3-羟基丙酸的EESI-MSⁿ分析结果相吻合, 说明土壤中确实存在该衍生物, 其可能是一种尿素在土壤里代谢过程的中间体. 本文结果表明, EESI-MS技术可以直接分析复杂基体样品中痕量物质的信号, 为研究尿素在土壤中的氮素转化机理提供了新的思路.

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.