What is gas chromatography (GC) mainly used for?

Gas chromatography (GC) is a powerful analytical technique primarily used for separating and analyzing volatile compounds in a mixture. The fundamental principle of GC involves vaporizing a sample and then passing it through a column that contains a stationary phase. The different components in the sample travel through the column at varying rates based on their individual volatilities and affinities for the stationary phase. This separation allows for the qualitative and quantitative analysis of the components as they elute from the column and are detected by a suitable detector.

The capability of GC to handle gases and vaporized samples makes it particularly suited for analyzing substances like hydrocarbons, solvents, and other volatile organic compounds, which are commonly encountered in various fields, including environmental monitoring, food and flavor analysis, and forensic science.

This contrasts with other methods mentioned, which do not focus on the separation of gaseous or volatile samples. For example, measuring pH levels involves titration techniques or special instruments unrelated to the separation of volatile substances, while reducing particle size and titrating unknown solutions address different aspects of chemical analysis altogether. Thus, gas chromatography's primary application lies firmly within the realm of separating and analyzing volatile compounds.