What is the RF value for aspirin?
How does TLC identify ibuprofen?
Ibuprofen assay was performed by TLC- densitometry using silica gel 60 F254 plates as the stationary phase and a mixture of chloroform: methanol (10: 1) as the best mobile phase. Standard solution of ibuprofen in the range of 2-10 mg/mL resulted in a regression equation y = 14293.868 + 4201.72x with r = 0.9973.
What is the RF value of paracetamol?
Results for TLC analysis
What is the ideal RF value?
between 0.3 and 0.7
Why is RF value important?
Rf value stands for the retardation factor value. It tells us how far the unknown pigment traveled in relation to the distance the solvent traveled. The Rf value is useful for scientists because it allows scientists to identify the pigment by comparing its Rf value to that of a known standard.
What do Rf values indicate?
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.
RF value (in chromatography) The distance travelled by a given component divided by the distance travelled by the solvent front. For a given system at a known temperature, it is a characteristic of the component and can be used to identify components.
How is RF value calculated?
The Rf value of a compound is equal to the distance traveled by the compound divided by the distance traveled by the solvent front (both measured from the origin).
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).
Why is RF useful?
What does a high RF value mean?
Definition. Rf = distance traveled by substance/distance traveled by solvent front. 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. The farther a compound travelled, the larger it’s Rf value.
Why is a high RF value bad?
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. Another run must be made using a less polar solvent to improve the separation.
Can an RF value be greater than 1?
Rf value can be used to identify compounds due to their uniqueness to each compound. Rx=distance of compound from origin / distance of compound x from origin While Rf can never be greater than 1, Rx can be (i.e., faster than the reference compound x). Apparatus and chemical required. 1.
Does higher RF mean more polar?
In general, the adsorptivity of compounds increases with increased polarity (i.e. the more polar the compound then the stronger it binds to the adsorbent). 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 affects Rf value?
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.
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.
How would Rf values change if a more polar solvent were used?
In general, how will Rf values change with increasing solvent polarity? Rf values increase with increasing solvent polarity as substance are more attracted to the solvent and therefore move with it.
Is caffeine more polar than aspirin?
Acetaminophen contains one amide and one phenolic group. Aspirin contains one carboxylic and one ester group. As Caffeine contains most number of heteroatoms in the functional group and it has lowest Rf value. So it is most polar.
Do more polar solvents elute faster?
Note that the more polar the solvent, the faster compounds elute, regardless of the compounds polarity. This will force compounds into the mobile phase, and result in faster elution/increased travel distance. It may also be helpful to remember that alumina and silica are much more polar than any organic solvent.
What would you expect to happen to the RF values if you use acetone?
What would you expect to happen to the Rf values if you used acetone instead of hexanes as the eluting solvent? Acetone is more polar so the compounds would travel faster, and the Rf values would be larger.
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