Distillation is a process by which a solution is heated, thereby utilizing evaporation to separate a liquid solvent and solid solute. A common type of solution is an aqueous solution, wherein a solute is dissolved in a water solvent. Saline sea water is an example of an aqueous solution that is processed through distillation to obtain the solute of NaCl, or salt.
What if you were a commercial producer of sea salt who wanted to determine if a petroleum oil spill has contaminated your supply? It would be impractical to drain a large amount of a body of water for large-scale distillation and analysis. The resources to perform the process may be expensive, and you would want to protect your crew from this potential hazard. In this case, selecting small samples of water and performing chromatography to determine the elemental composition would be more effective. A gas chromatographic machine will evaporate the liquid sample, allowing the machine to analyze the chemical characteristics and composition. Once the sea water is analyzed for contamination, you can make an informed decision about how to proceed with manufacturing sea salt.