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 o n a continuously coated moving wire which facilitates reproducible sol vent removal and analyte combustion, followed by drying of the CO2 and admission to the mass spectrometer. Routine precision and accuracy fo r 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 < de lta(13)C(PDB) < 83. Precision in the liquid chromatography mode is rou tinely similar to 1 parts per thousand and is limited by sample size. This system expands the range of online compound-specific isotope rati o analysis (CSIA) to thermally labile and nonvolatile compounds.