Determination of isopropylamine hydrochloride in isoproterenol hydrochloride, development and validation of analytical method

Isoproterenol hydrochloride; is a synthetic catecholamine that dilates blood vessels and stimulates β1 and β2 receptors. Isopropylamine is one of the starting materials used in the synthesis of isoproterenol hydrochloride active pharmaceutical ingredient, and its quantification is controlled by analytical method, since its amount in the final product should not exceed 0.15% according to the The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). In this study, determination of isopropylamine impurity was performed by high performance liquid chromatography system and pre-column derivatization. In the method, 1-naphthyl isothiocyanate was used as the derivatizing agent and the resulting 1-isopropyl-3-(naphthalen-1-yl)thiourea molecule was monitored at a wavelength of 230 nm. Analytical separation in the sample was made using a Phenomenex Luna Phenyl-Hexyl column (4.6 mm x 250 mm; 5.0 µm), 0.1% o-phosphoric acid and a 70:20:10 ratio acetonitrile, methanol and water mixed mobile phase system. Method validation studies were performed according to the ICH Q2(R1) guideline. Specificity from validation parameters; it was observed that the peak formed by the derivatized isopropylamine molecule was separated from the peak of the isoproterenol hydrochloride substance and the peaks of other impurities and was spectrally pure. The stability of the derivatized isopropylamine molecule was determined as 10 hours. The limit of detection (LOD) was calculated as 0.0021 µg/mL and the limit of quantification (LOQ) as 0.0071 µg/mL. It has been observed that the method is fast, robust, selective, reproducible and allows the determination of isopropylamine at low concentrations. Keywords: Isoproterenol hydrochloride, Isopropilamine, HPLC, Derivatization