HIGH-PRECISION LIQUID CHROMATOGRAPHY-COMBUSTION ISOTOPE RATIO MASS-SPECTROMETRY

Online liquid chromatography-combustion high-precision Carbon isotope ratio mass spectrometry (LCC-IRMS) is demonstrated for the first time with a direct interface to the liquid source. The interface is based on a continuously coated moving wire which facilitates reproducible solvent removal and analyte combustion, followed by drying of the CO2 and admission to the mass spectrometer. Routine precision and accuracy for compounds analyzed with the interface in the flow injection mode is about delta(13)C(PDB) = 0.5 parts per thousand over the range -28 < delta(13)C(PDB) < 83. Precision in the liquid chromatography mode is routinely similar to 1 parts per thousand and is limited by sample size. This system expands the range of online compound-specific isotope ratio analysis (CSIA) to thermally labile and nonvolatile compounds.