GLOSSARY OF TERMS: Filtration

ABSORPTION: The taking in, incorporation, or reception of gases, liquids, light, or heat.

BETA RATIO: Measurement of filter retention efficiency. Ratio of particles exposed to a filter (as feed stream) to particles present in the filtrate.

CATALYST: A compound that increases the rate of a reaction, although it does not itself undergo any net chemical change. Enzymes are biological catalysts.

DENATURATION: The process of changing the tertiary and/or quaternary structure of a proteinous macro molecule, thus causing inactivation or change in biological activity. Proteins may be denatured by heat, pH, or addition of agents such as urea or guanidinium hydrochloride.

EFFLUENT: Fluid that has passed through a filter.

FEED: The unfiltered liquid. Often used in the phrase “feed stream," which is the flow of liquid into the filtration system.

HOUSING: The device that encloses a filter element and directs the flow of fluid through it.

INJECTOR: System for introducing the sample or mobile phase into the column. May be either manual or automated. It is a good idea to filter the analyte to prevent the injector from clogging

LIVE STREAM: Sterilization by flowing saturated steam through a vented vessel or sterilization system, usually at 125 C and 20 PSI (can be performed up to 140 C and 35 PSI.)

MICROFILTRATION: Microfiltration is the process of removing particles from a liquid or gas by passing it through a porous medium. It generally involves removing particles between the sizes of 10 and 0.02 microns in liquids and down to 0.003 microns in gases.

PARTICULATE: Relating to or occurring in the form of fine particles.

RECOVERY: Ability of a filter to retain bacteria, DNA or other biomolecules from a solution. Percentage of a chemical that can be recovered after processing.

SEDIMENTATION: The removal of suspended solids from water or wastewater by gravity in a quiescent basin or clarifier.

UNLOADING: The release of contaminants initially captured by a filter.

WETTING AGENT: A surfactant added to a membrane to assure complete intrusion (wetting) by a high surface tension fluid such as water.

The terms and definitions for this issue’s Word Search come from a glossary of terms compiled by Pall Corporation (www.pall.com), a worldwide provider of filtration, separation, and purification solutions.