Determination of phenylpropanolamine hydrochloride and acetaminophen in pharmaceutical preparations by Raman spectroscopy.

Phenylpropanolamine hydrochloride and acetaminophen in mixtures have been determined, without prior separation, by Raman spectroscopy. Results are reported for both solution and solid samples. Direct measurement of solid samples, requiring only a brief period of mixing and grinding with potassium nitrate added as an internal standard, is shown to be particularly convenient and effective. Various data treatments to compensate for spectral overlap have been compared, and a correlation method has been shown to be most effective. For a sample typical of a cold remedy, in which the concentration of acetaminophen is 10 times that of the phenylpropanolamine hydrochloride, accuracy and precision were shown to be better than 1% for the measurement of acetaminophen and better than 3% for the measurement of phenylpropanolamine hydrochloride.