Reversed-phase high-performance liquid chromatographic and derivative UV spectrophotometric determination of α-phenylethylamine in phosphomycin

Two sensitive and selective methods were developed for the evaluation of α-phenylethylamine (α-PEA), an impurity possibly present in the antibiotic phosphomycin (PHO). The reversed-phase high-performance liquid chromatographic method uses a LiChrosorb NH2 column with acetonitrile-0.1M NaH2PO4 · H2O buffer as eluent and allows the simultaneous detection of PHO and α-PEA in a complex matrix such as pharmaceutical preparations. The amine gives a linear detection response over the range 15–85 μg/ml. The derivative spectrophotometric method can specifically discriminate the amine in the range 230–280 nm. The α-PEA concentration is determined by measuring the distance between the maximum at 250 nm and the adjoining minimum at 248 nm in the second-derivative spectrum. A linear correlation was found in the concentration range 15–160 μg/ml. For both procedures, no sample pretreatment is required.