Forced degradation study of abacavir using the electrochemistry-mass spectrometry setup

This article investigates the electrochemical oxidation of abacavir using a simple online setup, coupling an electrochemical flow cell with a mass spectrometer, as an alternative approach to forced oxidative degradation studies. Electrochemical oxidation of abacavir was performed on a glassy carbon electrode in only 3 min, using four different solvents: three containing 0.5 mol/L ammonium acetate, pH 7.0, with 0, 50, and 90% (v/v) methanol, and one containing 0.1 mol/L NaClO₄ in pure methanol. A total of seven degradation products were observed, with detector signals in different ratios depending on the solvent used. The results obtained in the EC-MS setup were compared with offline electrooxidation in static mode, performed for 5 h on the same working electrode, at the same potential, and in the same solvents as the oxidation in the EC-MS setup. The offline degraded samples were analyzed by HPLC with UV/VIS and MS detection. Of the seven monitored degradation products, six were observed in the offline mode. The abundance of individual signals was compared between the two approaches. The vast majority of degradation products were identical in both methods, and the most abundant ones were also in agreement. The study thus shows that, keeping in mind certain limitations in comparing the data, the online EC-MS approach can be used as a fast and simple indicative method for rapid screening of drug stability and susceptibility to oxidative degradation.