A Friendly Environmental CE Method to Determine Doxycycline Hyclate in Suppositories and Application to Tablet Assay

Background: The demand for green analytical methods is rising, mainly due its impact on the reduction of waste generation. The official method to assay Doxycycline Hiclate (DOXH) is HPLC, using an unusual column and a multi-component mobile phase. Objective: To develop a capillary electrophoresis method (CZE) to assay DOXH in suppositories and tablets. Methods: Doxycycline was analyzed in a CZE system using a fused silica capillary silica (effective length 40 cm), voltage 25kV, temperature 24 degrees C, detection at 260 nm and hydrodynamic injection of 50mBar/5s. The electrolyte was a mixture of acetonitrile and aqueous solution composed of 25 mM sodium carbonate and 5mM EDTA, pH 10.6. Results: The method was validated according to ICH requirements and DOXH detection was achieved at around 5 min. A linear relationship was observed in the range of 20 to 160 mu g.mL(-1), the method was precise, showing values of relative standard deviation below 2%. Accuracy was demonstrated by DOXH recovery values ranging from 98.0 to 102.0%, for all the formulations. The specificity was studied by the peak purity evaluation and by the good resolution between peaks of DOXH, degradation products and a related substance intentionally added to the sample solution. Robustness was evaluated by 2(3) full factorial design, and no effect on DOXH assay was observed under simultaneous variation in significant analytical parameters. Conclusion: This simple and inexpensive method may be used to determine DOXH in suppositories as well tablets, under identical analytical conditions and can be a green alternative to the HPLC official method.