Determination of ointments active ingredients and parabens by one analytical method – capillary GC with cool-on-column injection and FID detection

In the field of quality control of medicines every pharmaceutical is tested for compliance with the requirements of the normative document for this drug to assess the quality. Among the quality indicators are the content of active ingredients and the excipients content. The more analytical methods used in a normative document, the greater the time and effort of people in all areas where a drug is developed, manufactured and controlled. A fast, precise, accurate and sensitive method has been developed for the simultaneous determination of the active ingredients of ointments of camphor, L-menthol, methyl salicylate, benzyl nicotinate, nonivamide, capsaicin, dihydrocapsaicin, nordihydrocapsaicin together with excipients, which are often para-hydroxybenzoic acid esters (parabens). The proposed gas chromatographic technique was validated. Good sensitivity for the application area (fractions of µg/mL for active ingredients and units of µg/mL for parabens), high reproducibility (relative standard deviation (RSD) doesn’t significantly exceed 2%) and the accuracy of the proposed method were demonstrated. The practical application was shown on the example of commercially available ointments. Also several assumptions about retention mechanism of such compounds were given. It seemed interesting to us for adapting proposed GC method to other components of ointments (or another dosage forms).