Do Rf values indicate purity?
However, because Rf values are relative, not absolute, some compounds may have very similar Rf values. It is primarily used to determine the purity of a compound. A pure solid will show only one spot on a developed TLC plate.
What is the Rf value for pure aspirin?
0.67
The Rf values are 0.70 for salicylic acid and diflunisal, 0.67 for aspirin and methyl salicylate, 0.60 for gentisic acid, 0.57 for p-aminosalicyclic acid, and 0.40 for salicyluric acid.
How is the purity of the recovered caffeine determined?
Effective characterization of caffeine was achieved by determining Infrared spectrum, and employing a melting point apparatus and differential scanning calorimeter. The purity showed that the results that the extracted coffee was 90% pure.
What is Rf value?
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 do you interpret Rf values?
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.
Can Rf values be greater than 1?
Long Answer: Rf is the “Retardation Factor”, which is the ratio of the distance traveled by a compound in a mobile phase compared with the distance traveled by the front of the mobile phase itself. It is always greater than or equal to zero, and less than or equal to 1.
How is caffeine purified?
In the liquid-liquid (DCM-water) extraction, caffeine will be separated from the water-soluble pigments. After removing trace amounts of water, the low-boiling solvent is evaporated to yield the crude organic extracts. Further purification by sublimation results in white crystals of caffeine.
Is caffeine an organic compound?
caffeine, nitrogenous organic compound of the alkaloid group, substances that have marked physiological effects.
What does an RF value of 1 mean?
What is the rfvalue of caffeine in TLC analysis?
Further, if TLC analysis of a known sample of pure caffeine resulted in a spot with a Rfvalue of 0.23, then one may reasonably conclude that one of the compounds present in the unknown sample is caffeine.
What is the Rf value of Anacin?
Anacin’s Rf values clearly correspond to those of caffeine and aspirin. Substances: Aspirin Caffeine Acetaminophen IbuprofenExcedrin Anacin. Rf Values: 0.45 0.08 0.24 0.60 0.09 0.10 0.26 0.46 0.39. Aspirin Caffeine Ibuprofen Acetaminophen Exc.
What is the molecular weight of caffeine?
Caffeine PubChem CID 2519 Synonyms caffeine 58-08-2 1,3,7-Trimethylxanthine Molecular Weight 194.19 Date s Modify 2021-08-28 Create 2004-09-16
What is the KOC value of caffeine in soil?
The log Koc of caffeine was experimentally determined to be 2.87 and 3.89 in a silt loam soil and in a sandy loam soil respectively(1). According to a classification scheme(2), a log Koc range of 2.87 to 3.89 (Koc range of 741 to 7762) suggests that caffeine may have low mobility in soil to being immobile in soil.