Chromatography is primarily used for which of the following?

Chromatography is a technique primarily utilized to separate components of a mixture based on their differing affinities for a stationary phase and a mobile phase. This ability to separate mixtures is integral in various fields, including biochemistry, environmental analysis, and pharmaceuticals.

In chromatography, substances are distributed between the phases, where the affinity differences allow for separation. For example, in liquid chromatography, a sample is dissolved in a mobile liquid phase that moves through a stationary solid phase. Components that interact more strongly with the stationary phase will move more slowly compared to those with a weaker interaction, leading to effective separation. This principle is widely applied for purifying chemical compounds, separating biomolecules, and analyzing the composition of mixtures.

The other choices focus on distinct processes or applications unrelated to the primary function of chromatography. Measuring soil health involves various analytical techniques, including pH testing and nutrient analysis, which do not primarily utilize chromatography. Studying cellular respiration predominantly involves metabolic assays, not separation techniques. Producing vaccines involves bioprocessing and formulation activities rather than separation of mixtures, which is the core purpose of chromatography. Thus, the role of chromatography as a method for separation based on affinity differences is the most accurate and relevant choice.