| gel exclusion chromatography | <investigation> A lab technique, a type of column chromatography, used to separate the components of a mixture by molecular size and to collect the molecules which are larger than a certain size. It is similar to gel filtration, small molecules are slowed or trapped by the pores in the gel beads filling the column, while large molecules, too large to fit into the pores, slide past the beads and get to the bottom of the column first. at this point, the large molecules are collected. Gel exclusion refers to the maximum size of molecule which will fit into the gel bead pores, and this lab technique is used to collect the molecules in the mixture which are larger than, or excluded from, the pores. (09 Oct 1997) |
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| gel filtration chromatography | See: gel filtration. (05 Mar 2000) |
| parenteral absorption | Absorption by any route other than the alimentary tract. (05 Mar 2000) |
| mass energy absorption coefficient | <physics> The mass energy absorption coefficient, uen/p of a material for uncharged ionising particles is the product of the mass energy transfer coefficient, utr/p and (1 - g) where g is the fraction of the energy of secondary charged particles that is lost to bremsstrahlung in the material. (16 Dec 1997) |
| partition chromatography | The separation of similar substances by repeated divisions between two immiscible liquids, so that the substances, in effect, cross the partition between the liquids in opposite directions; where one of the liquids is bound as a film on filter paper, the process is termed paper partition chromatography or paper chromatography. (05 Mar 2000) |
| pathologic absorption | Parenteral absorption of any excremental or pathologic material into the bloodstream, e.g., pus, urine, bile, etc. (05 Mar 2000) |
| vitamin B12 absorption test | <investigation> This test measures the amount of vitamin B12 in the urine after ingesting a dose of B12. This test evaluates vitamin B12 absorption. The cells in the stomach produce a substance known as intrinsic factor. This substance combines with B12 to allow absorption in the distal ileum. The patient is given a small dose of radioactive B12 which can then be detected in the patients urine. Pernicious anaemia is the clinical result of B12 deficiency. Conditions that can result in an abnormal Schilling test include: deficiency of intrinsic factor, malabsorption or the development of an antibody to intrinsic factor. The Schilling test can be performed with or without administration of intrinsic factor to determine what the underlying cause for pernicious anaemia. Laxative use, renal insufficiency and hypothyroidism can all interfere with the results of this test. (27 Sep 1997) |
| percutaneous absorption | The absorption of drugs, allergens, and other substances through unbroken skin. Synonym: cutaneous absorption. (05 Mar 2000) |
| reversed phase chromatography | A form of partitionary chromatography in which the stationary phase is more polar than the mobile phase. (05 Mar 2000) |
| chromatography | <investigation> Techniques for separating molecules based on differential absorption and elution. Term for separation methods involving flow of a fluid carrier over a nonmobile absorbing phase. (18 Nov 1997) |
| chromatography, affinity | A chromatographic technique that utilises the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (12 Dec 1998) |
| chromatography, agarose | A method of gel filtration chromatography using agarose, the non-ionic component of agar, for the separation of compounds with molecular weights up to several million. (12 Dec 1998) |
| chromatography, deae-cellulose | A type of ion exchange chromatography using diethylaminoethyl cellulose (deae-cellulose) as a positively charged resin. (12 Dec 1998) |
| chromatography, gas | Fractionation of a vaporised sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix. (12 Dec 1998) |
| chromatography, gel | Chromatography on non-ionic gels without regard to the mechanism of solute discrimination. (12 Dec 1998) |