Simultaneous analysis of streptomycin, dihydrostreptomycin and their related substances by capillary zone electrophoresis

A capillary zone electrophoresis method was developed and validated for simultaneous separation of streptomycin (STM) and dihydrostreptomycin (DHS) with direct UV detection at 205 nm. Good selectivity was obtained within a short analysis time. Electrophoresis conditions were as follows: 50 mM sodium tetraborate including 5% (v/v) methanol at pH 10.25; fused-silica capillary, 44 cm (effective length 36 cm) x 50 mum I.D.; voltage, 15 kV; temperature, 25 degreesC. The method allows STM and DHS to be completely separated from their main related substances and each other, The robustness of the method was examined by means of a full-fraction factorial design to test the influences of buffer pH, concentration of buffer and of methanol. The parameters for validation such as linearity, precision, limit of detection, and limit of quantitation are also reported.