DIRECT DETERMINATION OF NON-UV-ABSORBING COMPOUNDS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A direct liquid chromatographic method with UV detection has been deve loped for the determination of ethambutol dihydrochloride, a chemother apeutic drug lacking in chromophoric groups. It allows the simultaneou s separation of [S,S(+)]-ethambutol from meso-[S,R(+/-)]-form and its synthetic precursor [S(+)]-2-amino-1-butanol, although it is not stere ospecific for the separation of the [R,R(-)]-enantiomer. Important fac tors affecting the selectivity and efficiency of separation (CuSO4 con centration, temperature and addition of an organic modifier in the mob ile phase) have been studied. Moreover the proposed method allows the quantitative determination of ethambutol dihydrochloride in pharmaceut ical formulations in order to verify the agreement with the claimed co ntent for the drug.