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RATIONALE Boron isotopes are a powerful tool for pH reconstruction in marine carbonates and as tracer for fluid-mineral interaction in geochemistry. Micro-analytical approaches based on laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) often suffer from effects induced by the sample matrix. In this study, we investigated matrix-independent analyses of B isotopic ratios and applied this technique to cold-water corals. METHODS We employed a customized 193 nm femtosecond laser ablation system (Solstice, Spectra-Physics) coupled to a MC-ICP-MS (Nu Plasma II, Nu Instruments) equipped with electron multipliers for in situ measurements of B isotope ratios (11B/10B) at the micron-scale. We analyzed various reference materials of silicate and carbonate matrices using non-matrix match calibration without employing any correction mode. This approach was then applied to investigates defined increments in coral samples from a Chilean fjord. RESULTS We obtained accurate B isotope ratios with a precision of ± 0.9‰ (2 SD) for various reference materials including silicate glasses (GOR132-G, StHs6/80-G, ATHO-G, and NIST SRM 612), clay (IAEA-B-8) and carbonate (JCp-1) using the silicate glass NIST SRM 610 as calibration standard, which shows that neither laser-induced nor ICP-related matrix effects are detectable. The application to cold-water corals (Desmophyllum dianthus) reveal little intra-skeleton variations in δ11B with average values between 23.27 and 26.09‰. CONCLUSIONS Our instrumental set-up provides accurate and precise B isotopic ratios independently of the sample matrix at the micron-scale. This approach opens a wide field of application in geochemistry, including pH reconstruction in biogenic carbonates and deciphering processes related to fluid-mineral interaction.