Determination of spectinomycin dihydrochloride by liquid chromatography with electrochemical detection

Spectinomycin dihydrochloride is determined by liquid chromatography with electrochemical detection. The drug is chromatographed on a reverse-phase Nucleosil C18 column using an eluent containing 0.02 M sodium citrate and 0.0015 M octyl sodium sulfate (pH 6.10 with perchloric acid) and acetonitrile (100:4). Detection is performed using a coulometric detector (porous carbon working electrode) at +0.85 V. The drug and primary degradation product are detectable. Detector response is linear to at least 20 micrograms/ml, which is four times the assay level. The procedure has relative standard deviations of +/- 1.21 to +/- 2.72% for three lots of bulk drug. Sensitivity is greater than 0.1 microgram/ml of spectinomycin (5 ng on column). Repeatability at this level is +/- 4.94%.