Determination of Residual Solvents in Drug Substances by Gas Chromatography with Thermal Desorption Cold Trap Injection

A simple and reliable method has been developed for the determination of residual solvents in drug substances by gas chromatography with thermal desorption cold trap injection. Residual solvents in a sample were desorbed by heating at a temperature higher than the melting point of the sample, then trapped in a cold trap cooled at -130°C. After the cold trap was heated, solvents were injected into an analytical column. These operations were performed automatically by the control unit of the injector. This method is useful for the determination of residual solvents in drug substances because of its high sensitivity without the interference of drug substances. As an example of the application of the method, residual solvents in five drug substances were determined.