Improved sensitivity of headspace gas chromatography and its application to residual solvents analysis of medicines

The sensitivity of headspace gas chromatography depends on the vapor pressure of the object component, and the vapor pressure depends on several parameters. One of these is the active coefficient which is influenced by solvent composition and coexisting components (e.g. salting effect). Improved sensitivity for various organic components in standard solution was investigated by dilution with water and salting effect, and applied to the analysis of residual solvents in medicines. Generally, sensitivity was highest when a 1.5 times volume of water was added to the standard solution using the salting effect with calcium chloride. In the case of a tablet in DMF solution, the peak area of toluene from a 1 ml sample with 1.5 ml of calcium chloride water solution (5 M) is 6.8 times larger than that from a sample without calcium chloride water solution.