Fast isotopic separation of B-10 and B-11 boric acid by CZE was demonstrated. The BGE contained 25 mM phenylalanine and 5 mM putrescine (pH 8.95). The running conditions were +25 kV at 20 degrees C with indirect photometric detection at 210 nm. Baseline separation was achieved in less than 9 min. RSD of migration times and corrected peak areas were less than 0.5 and 3%, respectively (n = 5). Linearity was demonstrated in the range 0.22 mM for B-11 and 0.2-0.5 mM for B-10.