Isocratic zwitterionic HILIC-ESI-MS method for assay of ropinirole and quantitation of degradation impurities in...

Given the therapeutic importance of ropinirole in Parkinson's disease and its long-term use, reliable quality control of this drug is required, with particular emphasis on impurity control in the finished pharmaceutical product. A zwitterionic hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry (HILIC-ESI-MS) method was developed and validated for the determination of ropinirole and three degradation impurities in pharmaceutical tablets. Chromatographic separation was achieved on a ZIC®-HILIC column (150 × 2.1 mm, 3.5 μm particle size, 200 Å) under isocratic elution with a mobile phase of 18.8 mM aqueous ammonium formate solution at pH 6.20 and acetonitrile in an 8:92 (v/v) ratio, delivered at a flow rate of 0.25 mL min^-1. Detection was performed in positive electrospray ionization mode using selected ion monitoring and the target analytes were determined within 10 min for assay and 16 min for impurity testing. The method was validated for linearity, accuracy, precision, sensitivity, robustness, and selectivity. Calibration curves showed good linearity over the concentration range of 21 to 122 ng mL^-1 with correlation coefficients of at least 0.997. Intra-day precision (% CV) did not exceed 6.7 %, while total precision ranged between 2.5 and 8.8 % for all compounds. The method was successfully applied to the analysis of commercially available ropinirole extended-release tablets. To the best of our knowledge, this is the first reported HILIC-ESI-MS method for the assay of ropinirole and the quantitation of three degradation impurities in pharmaceutical tablets.