Although high-precision isotope determinations are routine in many areas of natural science, the instrument principles for their measurements have remained remarkably unchanged for four decades. The introduction of continuous-flow techniques to isotope ratio mass spectrometry (IRMS) instrumentation has precipitated a rapid expansion in capabilities for high-precision measurement of C, N, O, S, and H isotopes in the 1990s. Elemental analyzers, based on the flash combustion of solid organic samples, are interfaced to IRMS to facilitate routine C and N isotopic analysis of unprocessed samples. Gas/liquid equilibrators have automated O and H isotopic analysis of water in untreated aqueous fluids as complex as urine. Automated cryogenic concentrators permit analysis at part-per-million concentrations in environmental samples. Capillary gas chromatography interfaced to IRMS via on-line microchemistry facilitates compound-specific isotope analysis (CSIA) for purified organic analytes of 1 nmol of C, N, or O. GC-based CSIA for hydrogen and liquid chromatography-based interfaces to IRMS have both been demonstrated, and continuing progress promises to bring these advances to routine use. Automated position-specific isotope analysis (PSIA) using noncatalytic pyrolysis has been shown to produce fragments without appreciable carbon scrambling or major isotopic fractionation, and shows great promise for intramolecular isotope ratio analysis. Finally, IRMS notation and useful elementary isotopic relationships derived from the fundamental mass balance equation are presented.

中文翻译：

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高精度连续流同位素比质谱法。

尽管高精度同位素的测定在自然科学的许多领域中都是常规的，但其测量的仪器原理在过去的40年中一直保持显着不变。在同位素比质谱法（IRMS）仪器中引入连续流技术已促使1990年代高精度测量C，N，O，S和H同位素的能力迅速扩展。基于固体有机样品的快速燃烧的元素分析仪与IRMS相连，以促进对未处理样品的常规C和N同位素分析。气体/液体平衡器可对未经处理的含水流体（如尿液）中的水进行O和H同位素自动分析。自动低温浓缩仪可对环境样品中的百万分之一浓度进行分析。毛细管气相色谱通过在线微化学法与IRMS相连，有助于对1 nmol的C，N或O的纯化有机分析物进行化合物特异性同位素分析（CSIA）。基于GC和CSRMS的氢和液相色谱与IRMS的接口两者都得到了证明，并且持续的进步有望使这些进步成为常规用途。使用非催化热解的自动位置特异性同位素分析（PSIA）已显示产生的片段没有明显的碳加扰或主要的同位素分馏，并显示了分子内同位素比率分析的巨大希望。最后，提出了从基本质量平衡方程推导出的IRMS表示法和有用的基本同位素关系。