Determination of the structure of a synthetic impurity in guaifenesin: modification of a high-performance liquid chromatographic method for phenylephrine hydrochloride, phenylpropanolamine hydrochloride, guaifenesin, and sodium benzoate in dosage forms.
An impurity present in all commercial guaifenesin-containing dosage forms examined was isolated and identified as 2-(2-methoxyphenoxy) 1,3-propanediol (VI). The eluant of a previously developed stability-indicating liquid chromatographic method for phenylephrine hydrochloride (I), phenylpropanolamine hydrochloride (II), and guaifenesin (III) was modified to yield a better separation between phenylpropanolamine and the impurity. The method was expanded to include sodium benzoate (IV), a preservative found in some liquid formulations.
D001565:Benzoates / Q000032:analysis; D019817:Benzoic Acid; D002214:Capsules; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004340:Drug Contamination; D004355:Drug Stability; D006140:Guaifenesin / Q000032:analysis*; D010656:Phenylephrine / Q000032:analysis; D010665:Phenylpropanolamine / Q000032:analysis
D001565:Benzoates; D002214:Capsules; D010656:Phenylephrine; D010665:Phenylpropanolamine; D006140:Guaifenesin; D019817:Benzoic Acid