Table of Contents
What does the retardation factor Rf value 1 means?
When RF=0, the sample remains at the origin, and for RF=1, the sample migrates with the solvent front and does not interact with the stationary phase. Illustration of the measurements used to calculate the retardation factor and variation of the plate height with solvent front migration distance.
Why is the RF value less than 1?
Rf is a fraction. It is the ratio of how far a substance travels up the chromatography paper compared to the distance the solvent has travelled. This means that it must be less than 1.
What does an RF value tell you?
The Rf values indicate how soluble the particular pigment is in the solvent by how high the pigment moves on the paper. Two pigments with the same Rf value are likely to be identical molecules. Small Rf values tend to indicate larger, less soluble pigments while the highly soluble pigments have an Rf value near to one.
Can the retention factor be 1?
An RF value will always be in the range 0 to 1; if the substance moves, it can only move in the direction of the solvent flow, and cannot move faster than the solvent.
Can Rf values equal 1?
By definition, Rf values are always less than 1. An Rf value of 1 or too close to it means that the spot and the solvent front travel close together and is therefore unreliable. This happens when the eluting solvent is too polar for the sample.
What is a high Rf value?
A high Rf (Ie 0.92) would refer to a substance that is very non-polar. Ie that substance moved a 92% of the entire distance the solvent traveled. A low Rf value (0.10) would refer to a substance that is very polar.
What are the known Rf values?
Rf values do not have units since it is a ration of distances. Rf = 0.66 (60% Ethanol)- if % is given it is assumed that the mixture is in water hence 60% ethanol 40% water. Rf = 0.78 (Ethanol-Methanol mixture {1:2})- a mixture of 1 part Ethanol and 2 parts Methanol
What is a good RF value?
The normal range of RF is from 0-20 u/ml. RF above 20 u/ml is not considered enough to diagnose RA, as there other reasons the RF level may be elevated.
What is the signigicance of Rf values?
The Rf value is a physical constant for an organic molecule and can be used to corroborate the identity of a molecule.
What is Rf value in chromatography measured in?
The Rf value is the retention factor used in the identification of organic compounds in a mixture. The Rf value is calculated by measuring the relative distance traveled by a particular organic compound with respect to the mobile phase. It is calculated in both paper chromatography and TLC.