[en] Using the spectral method the isotope analysis of lithium is carried out to specify the value of anomalies of lithium isotope composition in salts. Accuracy of the results obtained has been checked according to standard mixtures, prepared of isotopically enriched lithium chlorides (lithium-6 chloride-90.5% ⁶Li and 9.5% ⁷Li; lithium-7 chloride-0.02% ⁶Li and 99.98% ⁷Li). The analysis has shown that commercial salts of lithium can have considerably shifted isotope composition, which must be taken into account when calibrating the instruments and applying salts as standards of isotope ratio