Isotope-ratio-monitoring liquid chromatography mass spectrometry (IRM-LCMS): First results from a moving wire interface system

A Liquid Chromatography-Combustion (LC-C) Interface, based on a moving wire technique, has been built and tested. The LC effluent is deposited onto a transport wire, which carries the sample through solvent evaporation and combustion ovens. CO2 from the combustion step is analysed in an isotope ratio mass spectrometer. Performance of the interface was tested by loop injections of sucrose and glucose into a liquid flow of methanol/water (80/20). Accuracy and precision of delta(13)C(PDB)<1 parts per thousand was achieved for sample concentrations >500 mu g/ul (5 mu l loop), sufficient for studies at natural isotope ratios. In case of C-13 tracer applications the detection limit was determined to be about 20 pg carbon tracer (on wire).