Phenylpropanolamine（PPA）hydrochloride為一種通鼻塞藥劑，與2-hydroxynaphthaldehyde產生衍生化反應後，其可藉由二次衍生分光光度法檢測。吸收範圍介於386~392 nm。此方法應用於Tavegyl-D與Sinutab製備時phenylpropanolamine之檢測，變異係數為0.8~1.6%。經由氯仿萃取PPA後，以分光光度計可同時檢測水層中的paracetamol

Phenylpropanolamine (PPA) hydrochloride used as nasal decongestant agent was determined by second derivative spectrophotometry after derivatization with 2-hydroxynaphthaldehyde. The absorbance was measured between minimum-maximum of 386 nm-392 nm. The linear calibration range was obtained within 0.5~2.0 μg/mL. The method was applied for the determination of phenylpropanolamine from pharmaceutical preparations Tavegyl-D and Sinutab with coefficient of variation of 0.8~1.6%. Paracetamol present together with phenylpropanolamine could also be determined by spectrophotometry in aqueous phase after extraction of PPA in chloroform.