DETERMINATION OF SODIUM-ACETATE IN ANTISENSE OLIGONUCLEOTIDES BY CAPILLARY ZONE ELECTROPHORESIS

The determination of sodium acetate in antisense oligonucleotides puri fied by reverse phase chromatography in acetate buffer is important in both impurity profiling and drug concentration assay. A method has be en developed for the quantitation of sodium acetate in a 20-mer phosph orothioate oligonucleotide drug substance employing capillary zone ele ctrophoresis. Chloride was included as an internal standard to increas e accuracy and precision of the measurement. Interference due to oligo nucleotide matrix was eliminated by filtering the olignucleotide solut ion through a Centricon SR-3 column. The linear dynamic range for the method is 0.06-240 mu g/mL. The electrophoretic separation requires on ly 6 min. The method has been demonstrated to be simple and reliable f or the quantitation of acetate salts in oligonucleotide drug substance s.