Dynamic extraction of residual solvents from pharmaceutical formulations using a needle-type extraction device

This study developed a rapid screening method to determine residual solvents contained in a tablet formulation using a needle-type extraction device. For this, the tablet formulation was pulverized and the powdered sample was rapidly inserted into a pipette tip. After fixing the sample with quartz wool, the pipette tip was capped with a silicon septum. A needle-type extraction device packed with Carbopack X and a carbon molecular sieve was inserted into the pipette tip through the septum, and the gas sample was collected. During this gas sampling, pure N₂ gas was introduced into the pipette tip. The extraction time for collecting 100 mL of the sample was approximately 10 min. After gas sampling, the extraction needle was connected to a gas-tight syringe and 0.5 mL of pure N₂ gas (desorption gas) was collected. The extraction needle was then inserted into a heated gas chromatographic injection port. The extracted residual solvents were then thermally desorbed and determined using a gas chromatograph-flame ionization detector. The detector response is very low for carbon tetrachloride, although the proposed method showed sufficient sensitivity for five Class 1 compounds. Additionally, this study clearly indicated that the purge efficiency of residual solves with dynamic extraction is different between powdered pharmaceutical formulations.