specific interactions - type of intermolecular or surface interactions which is related to any specific polar or ionic groups of the analyte molecule

spherical packing - refers to spherical solid packing materials. Spherical packings are generally preferred over irregular particles.

See particles.

standard addition - a method of quantitative analysis where standard amounts of sample are added to the unknown; from the increase in peak height the concentration in the unknown can be estimated.

stationary phase - common name for the column packing material in any type of chromatography.

See HPLC adsorbents.

steric exclusion chromatography (SEC) - a major LC mode in which samples are separated by virtue of their size in solution. Also known as size-exclusion, gel permeation, gel filtration, or gel chromatography.

supercritical fluid chromatography (SFC) - a technique that uses a supercritical fluid as the mobile phase. The technique has been applied to the separation of substances that cannot be handled effectively by liquid chromatography (because of detection problems) or gas chromatography (because of the lack of volatility). Examples are separations of triblycerides hydrocarbons, and fatty acids. GC detectors and HPLC pumps have been used together in SFC.