Determination of leachable fatty acids in metered dose inhalation products by high performance liquid chromatography equipped with charged aerosol detector

There is no universal method for leachable studies, and this thesis aims to develop a new HPLC/CAD method for the analysis of fatty acids, which could be potential impurities in a metered-dose inhalation drug in the pharmaceutical industry, and to validate the developed method. In this study, the leachable analysis of fatty acids (myristic acid, linoleic acid, palmitic acid, oleic acid, elaidic acid, stearic acid, arachidic acid) that might leak from the valve part of the product was carried out using an HPLC/CAD system. During the method development phase, changes were made to method parameters, device and detector settings to determine all parameters required for validation. For the validation of the developed method, the following parameters were applied: selectivity (specificity), linearity and working range, LOD (limit of detection) and LOQ (limit of quantitation), accuracy (recovery), precision (repeatability-intermediate precision), robustness, and stability. For the chromatographic separation with the developed analytical method, a C18 column was used as the stationary phase, and a gradient system consisting of mobile phase A (0.5 mL formic acid in 1000.0 mL of purified water) and mobile phase B (0.5 mL formic acid in 1000.0 mL of acetonitrile) was used as the mobile phase. During validation, the selectivity parameter confirmed the method' s specificity, LOD and LOQ values were determined, and the linearity parameter demonstrated that the results were linear between LOQ and 150% concentrations. The accuracy parameter achieved recovery results, and the precision parameter ensured repeatable results. An intra-laboratory precision study showed that similar results were obtained when another analyst performed the analysis. With the robustness parameter, the system suitability conditions were met when the formic acid amount was adjusted to 0.5 mL/L ± 5% and the column temperature to 50°C ± 2°C. The stability parameter results showed that the standard solution was stable for 48 hours at 10°C, and the sample solution was stable for 3 hours at 10°C. In conclusion, a validated method was obtained for the analysis of leachable fatty acids through this study.