Laser ablation IRMS – the minimally destructive alternative for in-situ 𝛅13C analyses of solid or liquid matrices

LA IRMS (laser ablation isotope ratio mass spectrometer) is a thrilling alternative to EA IRMS and opens a world of possibilities! We evaluated LA IRMS various organic materials (pollen, wood, collagen, bone, tooth, keratin, bee products, airborne particulate matter, blood, etc.). For some we also present EA data for method equivalency. We use two instrumental set-ups; sample introduction via 1. LSX 213 G2+ 213 nm wavelength laser ablation system or 2. Fusions CO2 laser (both Teledyne Photon Machines) and an HS2022 IRMS via a CryoFlex sample preparation module (all Sercon). The sample chamber is an isoScell Δ100 (Terra Analitic) specifically designed for LA IRMS. The EA IRMS used for inter-instrument comparison is also Sercon. This setup allows for blank levels as low as 6E-10 (ca. 2% of sample-peak size). Establishing the optimal laser parameters is a two-step process; the first one is fine tuning the laser energy to ensure the sample is ablated efficiently. The next step requires finding the optimal spot size and ablation time necessary for producing sufficient aerosol to be converted into CO2 in the combustion furnace. When spatial resolution is crucial samples (e.g., wood, hair, fingernail, tooth) can be ablated at intervals of down to 20 𝛍m. As each ablation removes a minute amount of sample, replicate analysis will not be an issue for homogenous matrices.We show that with LA matrix-matching the reference material to the unknown sample might be unnecessary.