David m bliesner validating chromatographic methods percentage of online dating marriages that end in divorce
The degree to which a sample particle may adsorb to the stationary phase is determined by the relative polarity, or charge, that the particle may possess at a given time.
Partition chromatography in which separation is based mainly on differences between the solubilities of the components in the mobile and stationary phases. The stationary phase liquid is present as thin film on an inert solid support.
Ion-pair chromatography allows the separation of complex mixtures of polar and ionic molecules.
The selectivity is determined by the mobile phase supplemented with a specific ion-pairing reagent which large ionic molecules are having a charge opposite to the analyte of interest, as well as a hydrophobic region to interact with the stationary phase.
Classification of Chromatographic Methods: Chromatographic methods are of two types.
In column chromatography, the stationary phase is held in a narrow tube and the mobile phase is forced through the tube under pressure or by gravity.
A component with high affinity towards the stationary phase will take longer to travel through it than a component with low affinity towards the stationary phase and high affinity towards the mobile phase.
Classical methods use separations such as precipitation, extraction, and distillation and qualitative analysis by color, odor, or melting point.
In planar chromatography, the stationary phase is supported on a flat plate or in the pores of a paper.
Here the mobile phase moves through the stationary phase by capillary action or under the influence of gravity .
Ion-exchange chromatography where a resin coated solid is used as stationary phase which has ions (either cations or anions, depending on the resin) covalently bonded to it, and the solute ions of the opposite charge are electro statically bound to the surface.
When the mobile phase (always a liquid) is eluted through the resin, the electro statically bound ions are released as other ions are bonded preferentially.