Optimization of the sample pretreatment (chromatographic isolation) and the measurement protocol for the highly precise and accurate determination of the B-10/B-11 isotope ratio via multi-collector ICP-mass spectrometry with sample introduction via nebulization or laser ablation. Use of recent mussel shells of the Scheldt mouth for evaluation and calibration of the B isotope ratio proxy. Use of the proxy for obtaining information on the paleoclimate via analysis of, among other, fossil biogenic carbonates, speleothemes and ice cores.