polystyrene-divinylbenzene resin (PS-DVB) - the most common polymer base for ion-exchange chromatography. Ionic groups are incorporated by various chemical reactions. Neutral PS-DVB beads are used in reversed-phase chromatography. Porosity and mechanical stability can be altered by varying the cross-linking through the variation of the DVB content.

porosity - for a porous adsorbent, the ratio of the pore volume inside the particles to the volume of the solid particles. The pore volume is also used as a measure of porosity.

See pore volume.

preparative chromatography - chromatographic technique in which the purpose is the separation of sizable amounts of pure materials.

pulsating flow - flow originating from a reciprocating pump. Normally, the pulses are dampened out by a pulse damper, by an electronic pressure feedback circuit. or by an active damper pump head. Some detectors (e.g. RI or electrochemical) are affected by flow pulsations.

See also pressure dampers.