What is selectivity in chromatography?
Selectivity is defined in Equation 2 as. It is the ratio of capacity factors for two chromatographic peaks. Conceptually, a capacity factor is the ratio of the amount of time an analyte spends in the stationary phase to the amount of time it spends in the mobile phase.
What is adsorption chromatography?
Adsorption chromatography is a type of LC in which chemicals are retained based on their adsorption and desorption at the surface of the support, which also acts as the stationary phase (see Fig. 1.11). This method is also sometimes referred to as liquid-solid chromatography.
What is the stationary phase?
Stationary phase is the stage when growth ceases but cells remain metabolically active. Several physical and molecular changes take place during this stage that makes them interesting to explore. The characteristic proteins synthesized in the stationary phase are indispensable as they confer viability to the bacteria.
What selectivity means?
selectivity. / (sɪˌlɛkˈtɪvɪtɪ) / noun. the state or quality of being selective. the degree to which a radio receiver or other circuit can respond to and separate the frequency of a desired signal from other frequencies by tuning.
What does selectivity factor describe?
Selectivity factor is a quantifiable measure of how efficient an antibiotic is during the process of gene selection. A selectivity factor lower than 10 means the concentration of antibiotic needed for selection is too close to the toxic concentration for the transfected cells.
What is example of adsorption chromatography?
TLC is an adsorption chromatography technique. In this process a sheet of glass, plastic, or aluminium foil, which is coated with silica gel, aluminium oxide or cellulose acts as a stationary phase and a single solvent or a mixture of solvent like ethanol,chloroform act as mobile phase.
What is column adsorption chromatography?
Column adsorption chromatography uses a column packed with the solid stationary phase, a liquid (the mobile phase) runs through this column and specific molecules will adsorb to the solid. Compounds that aren’t adsorbed at all will simply run through the entire column and collect in a beaker at the bottom.
What is the difference between stationary phase and mobile phase?
The main difference between the mobile phase and stationary phase is that the mobile phase is the solvent moving through the column, whereas the stationary phase is the substance, which stays fixed inside the column.
What is mobile phase and stationary?
The stationary phase is the phase that doesn’t move and the mobile phase is the phase that does move. In paper and thin-layer chromatography the mobile phase is the solvent. The stationary phase in paper chromatography is the strip or piece of paper that is placed in the solvent.
Was ist der Retentionsfaktor?
Der Retentionsfaktor (R f-Wert) ist mit der Retentionszeit in der Säulenchromatographie vergleichbar und ist für jede Verbindung charakteristisch, aber vom chromatographischen System abhängig.
Was ist ein relativer Retentionsfaktor?
Eine Standardsubstanz, die unter gleichen Bedingungen auf der gleichen DC-Platte entwickelt wurde, ermöglicht das Einführen eines relativen Retentionsfaktors (R st-Wert ), da alle experimentellen Bedingungen nur schwer zu kontrollieren sind. R st = s x s Ref s Ref – Strecke zwischen Startlinie und Referenzzone.
Was ist der Unterschied zwischen Auflösung und Retention?
Die Auflösung beschreibt die Fähigkeit einer Säule, die Peaks, die uns interessieren, zu trennen. Die Auflösung berücksichtigt die Effizienz (N), die Selektivität (a) und die Retention (k). • Ein Wert von 1 ist der Mindestwert für das Auftreten einer messbaren Trennung, die auch eine angemessene Quantifizierung ermöglicht.
Was ist der Unterschied zwischen Selektivität und Retention?
• Die Selektivität hat dabei den größten Einfluss auf die Auflösung. Kleine Änderungen der Selektivität führen zu großen Veränderungen bei der Auflösung. • Die Retention hat nur einen bedeutenden Einfluss, wenn die k-Werte klein sind.