Determination of phenylpropanolamine and methoxamine using flow-injection with fluorimetric detection

A new flow-injection procedure for the determination of phenylpropanolamine and methoxamine is proposed. The method is based on the derivatization reaction of the primary amine group with o-phthalaldehyde in the presence of 2-mercaptoethanol using fluorimetric detection. The calibration graphs based on peak areas were linear in the ranges 5-200 ng ml(-1) for phenylpropanolamine and 0.2-6 ng ml(-1) for methoxamine. The detection limits were 3.8 and 0.13 ng ml(-1), respectively. The methods were applied to the determination of the drugs in commercial pharmaceutical preparations.