Methods are described for continuous monitoring of signals required for precise analyses of 13C, 18O, and 15N in gas streams containing varying quantities of CO2 and N2. The quantitative resolution (i.e. maximum performance in the absence of random errors) of these methods is adequate for determination of isotope ratios with an uncertainty of one part in 10(5); the precision actually obtained is often better than one part in 10(4). This report describes data-processing operations including definition of beginning and ending points of chromatographic peaks and quantitation of background levels, allowance for effects of chromatographic separation of isotopically substituted species, integration of signals related to specific masses, correction for effects of mass discrimination, recognition of drifts in mass spectrometer performance, and calculation of isotopic delta values. Characteristics of a system allowing off-line revision of parameters used in data reduction are described and an algorithm for identification of background levels in complex chromatograms is outlined. Effects of imperfect chromatographic resolution are demonstrated and discussed and an approach to deconvolution of signals from coeluting substances described.

中文翻译：

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同位素比监测质谱数据的采集和处理

描述了对含有不同量 CO2 和 N2 的气流中的 13C、18O 和 15N 进行精确分析所需的信号的连续监测方法。这些方法的定量分辨率（即在没有随机误差的情况下的最大性能）足以确定同位素比，不确定度为 10(5) 中的一部分；实际获得的精度通常优于 10(4) 中的一部分。本报告描述了数据处理操作，包括色谱峰起点和终点的定义和背景水平的定量、同位素替代物质色谱分离效应的允许、与特定质量相关的信号的积分、质量区分效应的校正、识别质谱仪性能的漂移，和计算同位素增量值。描述了允许离线修改数据缩减中使用的参数的系统的特性，并概述了识别复杂色谱中背景水平的算法。演示和讨论了不完美的色谱分辨率的影响，并描述了从共流出物质中解卷积信号的方法。