A toc system for the analysis of the d13c signature of estuarine and marine dissolved organic carbon

溶解有机碳的稳定同位素组成(d13C-DOC)为理解碳源和循环提供了强有力的信息，但由于分析限制，无法在天然河口和海水样品中进行常规测量。用来测量海洋样品中的d13C-DOC的方法往往冗长而繁琐，通常需要高度专业化、昂贵的设备、大量的样品体积，以及许多步骤来去除碳酸盐并将DOC定量转化为二氧化碳，以便最终通过质谱仪进行离线分析。最近，湿式氧化溶解有机碳分析仪和同位素比质谱仪的接口简化了淡水中d13C-DOC的测量，但对咸水河口/海洋样品的分析仍然被证明是困难的。我们通过低温捕集HTC分析仪出口的分析气体，成功地将高温催化氧化总有机碳分析仪与同位素比质谱仪(HTC-IRMS)连接起来，用于河口和海洋样品中d13C-DOC的常规分析(Panetta R.J.，Ibrahim M.，Gélinas，Y.(2008))。化学。80、5232-5239)。我们是目前世界上极少数能够在自然DOC浓度范围(从35微米到2000微米以上)和环境中遇到的盐度(&lt；0.1到36 g/kg)范围内常规测量样品的实验室之一，具有出色的d13C-DOC精度(±0.2/mil)和精密度(±0.3/mil)。

The stable isotope composition of dissolved organic carbon (d13C-DOC) provides powerful information towards understanding carbon sources and cycling, but analytical limitations have precluded its routine measurement in natural estuarine and seawater samples. The methods employed to measure d13C-DOC in marine samples tend to be long and tedious usually requiring highly specialized, expensive equipment, large sample volumes, and a number of steps to remove carbonates and quantitatively convert DOC into CO2 for eventual off-line analysis by mass spectrometry. Recent interfacing of wet oxidation-based dissolved organic carbon analyzers and isotope ratio mass spectrometers has simplified the measurement of d13C-DOC in freshwaters, but the analysis of salty estuarine/marine samples still proves difficult. We have successfully coupled the a high-temperature catalytic oxidation-based total organic carbon analyzer to an isotope ratio mass spectrometer (HTC-IRMS) through cryogenic trapping of analyte gases exiting the HTC analyzer for routine analysis of d13C-DOC in estuarine and marine samples (Panetta R.J., Ibrahim M., Gélinas, Y. (2008) Anal. Chem. 80, 5232-5239). We are one of the very few laboratories in the world currently capable of routinely measuring samples over the natural range of DOC concentrations (from 35 µM to over 2000 µM), and salinities (<0.1 to 36 g/kg) encountered in the environment, with excellent d13C-DOC accuracy (± 0.2 per mil) and precision (± 0.3 per mil).