Determination of Stearic Acid and Palmitic Acid in Medical Rubber Plug Extracting Solution by Non-derivative Gas Chromatography

A non-derivative gas chromatography (GC) for determining stearic acid and palmitic acid in the extracting solution of medical rubber plug has been established. Three different media (pH=3 acidic buffer solution, pH=10 alkaline buffer solution, 20% ethanol solution) were used to extract the rubber plug. The extracted solution was extracted by hexane, separated on a DB-FFAP (30 m×0.25 mm×0.25 μm) column, detected by a flame ionization detector (FID), and quantified by an external standard method. The results showed that the peaks of stearic acid and palmitic acid were symmetrical under optimal conditions. The separation effect was good and the linear curve fitted well. The average recoveries were 97.6%~100.5%, and the relative standard deviations (RSD) were 0.4%~2.3% (n=6). The detection limit (LOD) was 1.0 mg/L to 1.5 mg/L. The method is simple and accurate, and can be used for the determination of stearic acid and palmitic acid in the extracting solution of medicinal rubber plug.