Collaborative study of an on-column periodate reaction method for the determination of ephedrine sulfate in sirups.

Fifteen laboratories collaboratively studied a method for the quantitative ultraviolet determination of ephedrine sulfate in sirups. Ephedrine is separated from water-soluble impurities and strong acids by elution from a weakly basic Celite column. Further cleanup is accomplished by retention of the ephedrine on a weakly acidic column while the weak acids, weak bases, and organic-soluble neutral compounds are eluted. Ephedrine is eluted from the column after neutralization with NH3 and is converted to benzaldehyde via an on-column periodate reaction. The samples collaboratively studied consisted of 2 commericial ephedrine-containing sirups and 2 commercial non-ephedrine-containing sirups to which ephedrine was added. Recoveries for the spiked sirups averaged 100.7 and 100.3% for mixtures containing 2.5 and 5.0 mg ephedrine sulfate/ml, respectively. The means and standard deviations for the commercial preparations were 4.088 plus or minus 0.068 and 2.375 plus or minus 0.053 mg/ml. The method has been adopted as official first action and has been incorporated into the official method for phenylpropanolamine hydrochloride, 38.199-38.203.