HPLC Determination of Norepinephrine Bitartrate in 5% Dextrose Injection on Underivatized Silica with an Aqueous-Organic Mobile Phase

A high performance liquid chromatographic procedure has been developed for the assay of norepinsphrine bitartrate in 5% dextrose injection containing up to a 500 fold excess of ranitidine. The separation and quantitation are achieved on a 22-cm underivatized silica column at ambient temperature (22 +/- 1-degrees-C) using a mobile phase of 50:50 v/v 5 mM phosphate buffer, pH 3.0 - acetonitrile at a flow rate of 1.0 mL/min with detection at 280 nm. It was shown that the predominant mechanism of retention for the drug on silica was cation exchange. The method showed linearity for norepinephrine over the 1 - 128 mug/mL range (r2 = 0. 9999, n = 8). Accuracy and precision were in the 0.9 - 2.3% and 0.63 - 3.3% ranges, respectively. The limit of detection was 26 ng/mL based on a signal-to-noise ratio of 3.