Use of Thin-Layer Chromatography (Tlc) for Identification of Aircraft Engine Oil Components

摘要

Thin-layer chromatography (TLC) using a silica gel adsorbent on a plastic backing, and n-heptane-acetone (95:5) developing solvent, permits useful separation of (a) esters derived from pentaerythritol, dipentaerythritol, and dibasic acids, (b) silicones, and (c) petroleum-based fluids. Esterification mixtures of both pentaerythritol and dipentaerythritol could not be resolved into their respective homologs. With benzene developing solvent, the caproate and valerate of pentaerythritol could be separated; in other respects, the solvent was less satisfactory than n-heptane-acetone because of its tendency to cause streaked chromatograms. Dibasic acid and trimethylolpropane esters could not be differentiated except by saponification and resolution of the liberated acids with benzene-acetone solvent (85:15). TLC shows some promise for rapid, specific separations, e.g., esters and silicones from petroleum-based oils and hydraulic fluids. Even with additional refinements of the method, however, results as precise or complete as those obtained with gas-liquid chromatography (GLC) or nuclear magnetic resonance (NMR) appear improbable. (Author)