Chromatography the term

Equation 11.15 is applicable to most forms of adsorption and partition chromatography. In the case of adsorption chromatography, the term tds simply represents the average time needed for molecular detachment from the adsorbing surface. Detachment is a straightforward rate process involving the breaking of the ties between surface sites -S and solute molecules M. If this process is represented by... 

Planar chromatography The term used to describe chromatographic methods that make use of a flat stationary phase the mobile phase migrates across the surface by gravity or capillary action. 

Equations 29 and 30 hold both for gas and liquid chromatography. In the case of gas chromatography the term al(B ) can always be neglected. 

The first step in the selection of the size-exclusion separation system is the choice of the mobile phase. We need to select a mobile phase in which the analytes, usually polymers, are soluble. This, in turn, determines the selection of the stationary phase, spedfically, whether we select a padring designed for organic or aqueous size-exclusion chromatography (the term aqueous may include polar solvents). If the goal of the separation is a molecular-weight determination, the requirements for the mobile phase-column combination are quite stringent ... 

It is known that the term L/u is equal to the holdup time tu-In the case of linear chromatography the term dqi/dct is equal to the linear adsorption coefficient K, so that for low concentrations the retention time can be calculated from ... 

What are peaks A peak is defined as the time during data acqnisition where the concentration (abundance) of a given ion (specific mlz) is larger than the background electrical noise. (Note that in chromatography the term peak refers to the detection of a separated component, from an injected mixture, eluting from a chromatographic column). 

For the purpose of chromatography, the term adsorption has limited meaning it usually denotes Interactions involving hydrogen bonding and weaker electrostatic forces of the substance with the adsorbent. The solute molecule which interacts more with the adsorbent, which is also the stationary phase, is retarded more while less interacting solute molecules are retmded less. In this way a separation of sample components is achieved. 

ION EXCHANGE. A process whereby ions of the same charge sign replace one another in a given phase. In chromatography, the term usually refers to systems in which the stationary phase is made up of an ionic polymer. This can be a synthetic resin, a cellulose or Sephadex-type exchanger, or various types of inorganic materials. 

Inverse gas chromatography. The term inverse refers to the fact that the method is used to examine the stationary phase. Here, the injected vapour sample is referred to as the probe. 

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