Functional Polytetrafluoroethylene Membrane-Assisted Purge and Trap Detection of Residual Solvents in Pharmaceutical Formulations Using a Needle-Type Extraction Device

This study proposes a novel analytical method for the sensitive and rapid detection of residual solvents in pharmaceutical formulations. In this method, a powdered tablet is dissolved and treated via purge and trap extraction using a functional polytetrafluoroethylene (PTFE) membrane and a needle-type extraction device. Specifically, the powdered sample and sodium chloride were added to 5 mL of pure water in a glass solid-phase extraction cartridge, followed by stirring until the dissolution of the solids. Subsequently, 100 mL of headspace gas was collected using a needle-type extraction device packed with Carbopack X and carbon molecular sieve as adsorbents. During the active sampling, a purging gas was introduced into the solution from the bottom of the cartridge through a functional PTFE membrane, which retained the solution while allowing the purging gas to pass. The typical sample collection time was 10 min. Following the sample collection, the extraction needle was directly inserted into a heated gas chromatographic injection port, and the extracted analytes were thermally desorbed and analyzed using a flame ionization detector. The limits of detections for benzene, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, and 1,1,1-trichloroethane (Class 1 compounds) were 0.005, 0.5, 0.005, 0.01, and 0.01 w/w ppm, respectively. The recovery of the target compounds did not depend on the formulation, and the proposed method demonstrated sufficient recovery and sensitivity for hydrophobic analytes, whereby allowing simple and rapid sample preparation.