Development of a Simple Extraction Procedure and an HPLC Method for the Determination of Delmopinol in a Challenging Rubbery Dental Chew

Background Delmopinol hydrochloride (delmopinol) is widely used in oral hygiene products such as dental chews for preventing dental plaque buildup and gingivitis. Objective This study aimed to develop a simple and inexpensive extraction method, followed by a stability-indicating reversed-phase HPLC (RP-HPLC) method for the determination of delmopinol from rubbery dental chews. Methods The extraction method was optimized in terms of pH, temperature, solvents, repeatability, and reproducibility. Delmopinol was extracted from the rubbery dental chews using 6 N NaOH-MeOH (1 + 1, v/v) at 65 degrees C. The delmopinol peak was eluted in about 7 min by gradient elution on a pH-stable (alkaline) Phenomenex Gemini-NX-C18 column (50 x 4.6 mm id, 110 angstrom, 3 mu m particle size) maintained at 50 degrees C. Mobile phase A was composed of aqueous 10 mM ammonium hydroxide and mobile phase B was acetonitrile. The analyte was monitored by UV detection at 220 nm with a flow rate of 2.0 mL/min. Results The method was successfully validated as per the current International Conference on Harmonization guidelines for delmopinol with respect to specificity, linearity (R-2 >0.999), accuracy, precision, LOQ (2 mu g/mL), LOD (0.6 mu g/mL), and robustness. The reliability of the method was also demonstrated by batch analysis of 132 dental chews. Conclusion A simple extraction method and RP-HPLC method were successfully developed and validated for the determination of delmopinol from rubbery dental chews.