Analysis of biochemical pathways typically involves feeding a labelled precursor to an organism, and then monitoring the metabolic fate of the label. Initial studies used radioisotopes as a label and then monitored radioactivity in the metabolic products. As analytical equipment improved and became more widely available, preference shifted the use stable ‘heavy’ isotopes like deuterium (²H)‐, carbon‐13 (¹³C)‐ and nitrogen‐15 (¹⁵N)‐atoms as labels. Incorporation of the labels could be monitored by mass spectrometry (MS), as part of a hyphenated tool kits, e.g. Liquid chromatography (LC)–MS, gas chromatography (GC)–MS, LC–MS/MS. MS offers great sensitivity but the exact location of an isotope label in a given metabolite cannot always be unambiguously established. Nuclear magnetic resonance (NMR) can also be used to pick up signals of stable isotopes, and can give information on the precise location of incorporated label in the metabolites. However, the detection limit for NMR is quite a bit higher than that for MS.

中文翻译：

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使用稳定的同位素标记的前体分析植物的次生代谢。

生化途径的分析通常涉及将标记的前体喂入生物，然后监测标记的代谢命运。最初的研究使用放射性同位素作为标记，然后监测代谢产物中的放射性。随着分析设备的改进和广泛使用，人们偏爱使用稳定的“重”同位素，如氘（² H），碳13（¹³ C）和氮15（¹⁵N）-原子作为标签。作为结合工具套件的一部分，可以通过质谱（MS）监控标记的掺入，例如液相色谱（LC）–MS，气相色谱（GC）–MS，LC–MS / MS。MS具有很高的灵敏度，但是不能始终明确确定给定代谢物中同位素标记的确切位置。核磁共振（NMR）也可用于拾取稳定同位素的信号，并可提供有关代谢物中掺入标记物精确位置的信息。但是，NMR的检出限比MS的检出限高很多。