Development of a HPLC/MS/MS method for simultaneous determination of tinidazole, dyclonine and chlorhexidine in rat plasma and its application in the pharmacokinetic research of a film-forming solution.

A rapid and sensitive HPLC/MS/MS method was developed and validated for simultaneous determination of tinidazole, dyclonine and chlorhexidine, the three main components of a film-forming solution, in rat plasma. The plasma samples were pretreated by solid phase extraction (SPE) method. Separation was achieved on a Phenomenex Gemini C(18) column (50 mm × 2.0 mm, 5 μm) using an isocratic mobile phase system composed of methanol-ammonium formate (10 mM)-formic acid (56:44:0.2, v/v/v) (pH 3.5) at a flow rate of 0.2 mL/min. Analytes were determined by tandem mass spectrometry with electrospray positive ionization and multiple-reaction monitoring (MRM) mode. The monitoring ions were (m/z) 247.4 → (m/z) 81.9 for tinidazole, (m/z) 290.1 → (m/z) 97.8 for dyclonine, (m/z) 505.0 → (m/z) 335.3 for chlorhexidine and (m/z) 282.1 → (m/z) 212.0 for phentolamine (internal standard). The calibration curves were linear in the range of 2-1000 ng/mL for the three components. The precision and accuracy of the method were well within the generally accepted criteria for biomedical analysis. It has been successfully applied to the pharmacokinetic research of a film-forming solution in rat.