Headspace Solid Phase Microextraction - GC/C-IRMS for Delta 13CVPDB Measurements of Mono-aromatic Hydrocarbons Using EA-IRMS Calibration

This work concerns the calibration of the delta 13C vs. VPDB of BTEX compounds using EA-IRMS with the aim of using them as standards on a headspace-SPME-GC-C-IRMS system. NBS19 and LSVEC isotopic reference materials were used to establish the scale for the delta 13C vs. VPDB measurements by EA-IRMS of i) the CO2 gas used as an in-house reference on a headspace-SPME-GC-C-IRMS system and of ii) five pure-liquid-phase organic compounds (BTEX). As the BTEX compounds could not be analysed without He dilution, a set of reference materials was analysed similarly and used for validation. The measured delta 13C vs. VPDB of these references with He dilution show systematic bias of 1 permil relative to their assigned values. The bias was corrected using a calibration applied to the measured delta 13C vs. VPDB of the BTEX. A comparison was made between the delta 13C vs. VPDB measured on the same BTEX components by EA-IRMS (with calibration) and by headspace-SPME-GC-C-IRMS techniques and this showed good agreement.JRC.D.4-Isotope measurement