Analysis of the nitrogen mustard mechlorethamine in topical pharmaceutical preparations by high-performance liquid chromatography

Mechlorethamine in topical pharmaceutical formulations was derivatized with benzenethiol to form the disubstitution product and analyzed by normal-phase HPLC on silica gel using dibutyl phthalate as an internal standard. The derivatization reaction, purification, and isolation were conveniently performed in a single test tube. Analyses were successfully performed on three types of ointment formulations: anhydrous hydrophobic petrolatum-based ointments, anhydrous hydrophilic ointments, and hydrous hydrophilic ointments. Precision for the analysis of mechlorethamine standard or mechlorethamine in ointments ranged from 0.08 to 0.52% RSD (n = 6). Recoveries from ointments spiked with 0.02% mechlorethamine hydrochloride were 98.4-100.4%. The chromatograms were clean, showing minimal or no interference from ointment excipients or reagents.