Quick Answer: What Is An RF Value And How Is It Calculated?

What does a high RF value mean?

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.

IE that substance was only able to move 10% of the entire distance the solvent traveled.

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Why is RF value important?

This allows unknowns to be compared to known materials. If the retention factor of an unknown does not match that of a known material, they are not the same compound. … Interactions of the individual components with each other and the concentration of the component in the sample will both affect the Rf value.

Why is RF 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.

Is a higher Rf value better?

The stronger a compound is bound to the adsorbent , the slower it moves up the TLC plate. Non-polar compounds move up the plate most rapidly (higher Rf value), whereas polar substances travel up the TLC plate slowly or not at all (lower Rf value).

What factors affect the RF values?

Retention Factor Rf values and reproducibility can be affected by a number of different factors such as layer thickness, moisture on the TLC plate, vessel saturation, temperature, depth of mobile phase, nature of the TLC plate, sample size, and solvent parameters. These effects normally cause an increase in Rf values.

What is Rf value and how is it calculated in paper chromatography?

The Rf value is defined as the ratio of the distance moved by the solute (i.e. the dye or pigment under test) and the distance moved by the the solvent (known as the Solvent front) along the paper, where both distances are measured from the common Origin or Application Baseline, that is the point where the sample is …

What is Rf value full form?

The Rf value – or to give it its full name, the Retention Factor – is a measure of how far something runs in chromatography. It is a ratio of the distance travelled by something compared to the solvent (as in paper or thin layer chromatography (TLC)) or dye-front (as in SDS-PAGE).

What does it mean if the RF value is 0?

did not moveThe distance a particular molecule, or spot, travels relative to the distance travelled by the eluting solvent is called the Rf value. The Rf value ranges from 0 (indicating the molecule did not move up the plate at all) to 1 (indicating the molecule traveled all the way up the plate).

What does a smaller Rf value mean?

A small Rf indicates that the moving molecules are not very soluble in the hydrophobic (non-polar) solvent; they are larger and/or have a greater affinity for the hydrophillic paper (they have more polar groups) than molecules with a larger Rf.

Which pigment has the highest RF value?

LuteinPigmentRf value rangeRelative positionLutein0.22-0.28Below, or almost at the same level of, the highest greenViolaxanthin0.13-0.19Below, or almost at the same level of, the highest greenNeoxanthin0.04-0.09Below, or almost at the same level of, the highest green

What is the basic principle of paper chromatography?

Principle of paper chromatography: The principle involved is partition chromatography wherein the substances are distributed or partitioned between liquid phases. One phase is the water, which is held in the pores of the filter paper used; and other is the mobile phase which moves over the paper.

What does the 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.

What is a good RF value?

The best Rf (retention or retardation factor) lies between 0.3 and 0.7. If you want the Rf of your TLC spot to be smaller, i.e., the spot to be lower down on the plate, you must decrease the eluent polarity.

Why RF values are different?

The larger an Rf of a compound, the larger the distance it travels on the TLC plate. When comparing two different compounds run under identical chromatography conditions, the compound with the larger Rf is less polar because it interacts less strongly with the polar adsorbent on the TLC plate.

What does a substance’s RF value depend on?

Retention factor values in thin layer chromatography are affected by the absorbent, the solvent, the chromatography plate itself, application technique and the temperature of the solvent and plate.