We provide ¹³C isotope analysis of water-soluble organic compounds in aqueous mobile phase using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Compounds must generally be isolated from bulk sample materials, such as soils, sediments, or biological tissues, using multi-step preparative procedures prior to chromatographic analysis. Unlike GC-C-IRMS, LC-IRMS does not require the derivatization of compounds prior to analysis. In LC-IRMS, individual compounds are first separated via high-performance liquid chromatography in an aqueous mobile phase.  Following separation, the organic carbon of each compound is then oxidized to CO₂ and transferred to an IRMS where the ¹³C/¹²C ratio of the CO₂ is measured.

Please note that nitrogen isotope ratios (¹⁵N/¹⁴N) cannot be currently analyzed by LC-IRMS.