Determination of isotopic ratio of boron in boric acid solutions by ATR–FTIR spectroscopy

Due to the low atomic mass of boron, its different isotopes (B-10 and B-11) leads to a measurable impact on vibrational spectra. Indeed, a shift in the asymmetric stretching of the dissolved species has been found using attenuated total reflectance infrared spectroscopy, and those of acid species is higher than those of the borate ion (41 cm−1 vs. 20 cm−1, respectively). A calibration from pure B-10 to pure B-11 boric acid has been performed, leading to an accuracy higher than 0.5% on the B-10 percentage of 0.1 M solution of mixtures of the two isotopes.