Chromatography is the separation of components in a mixture based on their chemical nature. Chromatography can be performed in either liquid (HPLC) or gas (GC) forms. Liquid chromatography, specifically High Pressure Liquid Chromatography (HPLC), involves a stationary phase (sorbent), a mobile phase (liquid) and the analyte or compounds of interest. Analytes or compounds of interest are injected onto an HPLC column (packed with sorbent that contains a variety of chemistries) in mobile phase. As the mobile phase, which is carrying the analyte or compounds of interest, travels across the stationary phase, the analyte or compounds of interest separate from each other as they interact with the stationary phase, each eluting from the column at various times. Gas chromatography (GC) is similar to HPLC in that is utilized with working analytes or compounds of interest that can be vaporized without decomposing. In GC, gas is used instead of a liquid (like in HPLC). As analytes or compounds of interest travel in the gas mobile phase and interact with the stationary phase, eluting at various times.

The void volume corresponds to the amount of mobile phase in an LC system. In most separation modes the void volume would be equivalent to the amount of mobile phase needed to elute a compound that doesn't interact with the stationary phase and is hence unretained. In size exclusion, analytes are not separated based on chemical interactions with the stationary phase but rather their ability, based on size, to enter pores in the stationary phase. Therefore, in size exclusion the terms total permeation and total exclusion volume have greater significance than void volume. The total permeation volume corresponds to the amount of mobile phase in the system, including that in the pores of the stationary phase, whereas the total exclusion volume does not include the mobile phase within the pores of the stationary phase. Consequently, the total permeation volume corresponds to the amount of mobile phase needed to elute a compound that is small enough to completely enter into the stationary phase pores and the total exclusion volume is the amount of mobile phase needed to elute a compound that is entirely excluded from the stationary phase pores.

Microelution SPE is essentially miniaturized solid phase extraction. The technique is ideal for analysts that have small or limited sample volumes or for those that want to save time by skipping the dry down step. Typical sample volumes are between 10–100 µL, and elution volumes can be as low as 25 µL and usually <150 µL, eliminating the need to perform a dry down step.

All RC, CA, and PTFE Phenex syringe filters come with a HPLC certificate of analysis. These filters include a certificate in every box to be low in extractables for trace analysis and sensitive detection methods.

Protein precipitation results from changing the solubility of the protein in solution by the addition of various precipitants such as organic solvent, metal ion, acid, and salt. Precipitation by organic solvent or acid is most commonly used. Organic solvent solvates the hydrophobic region on the protein surface and displaces water molecules. This causes an increase in electrostatic interactions, encourages attraction between charged molecules, and proteins aggregate as a result; this reduces their solubility, causing precipitation. Acids form insoluble salts with proteins, causing precipitation.