How do you calculate Rf values for pigments?
Rf = (distance moved by pigment)/ (distance moved by solvent)
- Rf for carotenes = 9.7cm/9.8cm = 0.99.
- Rf for xanthophylls = 7.2cm/9.8cm = 0.73.
- Rf for chlorophyll a = 5.1cm/9.8cm = 0.52.
- Rf for chlorophyll b = 3.7cm/9.8cm = 0.38.
Why do pigments have different Rf values?
The pigments are carried at different rates because they are not equally soluble. A pigment that is the most soluble will travel the greatest distance and a pigment that is less soluble will move a shorter distance.
What does it mean when a pigment has a high Rf value?
High Rf values from TLC using a nonpolar solvent means the pigment is more nonpolar. Lower Rf values mean the pigment is more polar.
What is the Rf value of xanthophyll?
Result and Discussion
| Distance travelled by the pigments (cm) | Rf value of pigments | |
|---|---|---|
| Solvent Front | 3.6 | – |
| Carotenoids | 3.3 | 0.89 |
| Chlorophyll a | 3.2 | 0.85 |
| Xanthophyll | 2.5 | 0.69 |
What are the 4 types of plant pigments?
Plant pigments are classified into four main categories: chlorophylls, anthocyanins, carotenoids, and betalains.
Are pigments polar or nonpolar?
The pigments represent a wide range of polarity from the chlorophylls and carotenoids which are very water insoluble (hydrophobic or nonpolar) and found embedded in membranes to the anthocyanins which are very water soluble (hydrophilic or polar).
Which pigment has the highest Rf value?
Chlorophylls are the pigments primarily responsible for photosynthesis. They absorb red and blue light, and reflect green light, which is what gives leaves their green colour.
…
Explanation.
| Pigment | Rf value |
|---|---|
| β-carotene | 0.98 |
| Chlorophyll a | 0.59 |
| Chlorophyll b | 0.42 |
| Anthocyanins | 0.32-0.62 |
Does a higher Rf value mean more soluble?
A large Rf would be characteristic of a more hydrophobic compound, since hydrophobic compounds will be more soluble in the more mobile, non-polar solvent, and so will travel farther than hydrophilic compound.
What pigment is most polar?
Chlorophyll b is a more polar (water-loving) pigment than the other pigments found in spinach extracts and is therefore more strongly attracted to the polar surface of the paper than to the nonpolar solvent.
Which pigment is more nonpolar?
Betacarotene and Chlorophyll A are considered more non-polar in nature because they have less functional groups with oxygen, while xanthophyll and chlorophyll B are considered more polar in nature.
What are 3 pigments found in leaves?
More complicated diagrams will be displayed to illustrate the structures of the three types of pigments that are present during the aging of leaves: chlorophylls, carotenoids, and anthocyanins.
What is the name of pigment?
Major plant pigments and their occurrence
| Pigment | Common types |
|---|---|
| Chlorophylls | Chlorophyll |
| Carotenoids | Carotenes and xanthophylls (e.g. astaxanthin) |
| Flavonoids | Anthocyanins, aurones, chalcones, flavonols and proanthocyanidins |
| Betalains | Betacyanins and betaxanthins |
Which pigment is more polar?
Which pigment is most nonpolar?
What factors affect the Rf values?
Factors affecting Rf value in paper chromatography
- The solvent system.
- Composition of the mobile phase.
- The working temperature of the system.
- The quality of the paper used.
- The distance through which the solvent runs.
- The quality and nature of solvents used.
- The polarity of components.
- The pH of the solvent or mobile phase.
What do Rf values tell us?
Rf values in chromatography are the basic requirement of the whole experiment. These values tell us whether the analyte (solute) is more affinitive with stationary or the mobile phase. Rf values evaluate the polarity, relative masses, and relative solubilities with stationary and mobile phases, etc.
Which pigment is most soluble in chromatography?
carotene xanthophyll
The pigment that traveled the furthest was carotene xanthophyll because it was the most soluble in the solvent.
Which pigment is the most nonpolar?
Carotene moves the farthest because it is the most nonpolar of the pigments and it is attracted more strongly to the acetone-ligroin mixture (mobile phase) than to the paper.
How many types of pigments are there?
two types
There are basically two types of pigments and they are: Inorganic pigments. Organic pigments.
Is silica a pigment?
Silica is not commonly used as a pigment, however, it is found in grounds, primers and wood fillers. Silica is used in the manufacture of glass, water glass, abrasives, ceramics and enamelware.
Which pigment is most soluble?
The pigment that traveled the furthest was carotene xanthophyll because it was the most soluble in the solvent.
What do Rf values mean?
The ratio of the distance the compound travels to the distance the solvent travels is called the Rf value. The symbol Rf stands for “retardation factor” or “ratio-to-front”. It is expressed as a decimal fraction.
What is a good Rf value?
A desirable Rf value lies between 0.3 and 0.7, since it is likely that other compounds present in the mixture will be visible on the TLC plate when the Rf is in this range.
What are the two types of pigments?
Based on the method of their formulation, pigments can be categorized into two types: inorganic pigments and organic pigments.
What is the pigment called?
Biological pigments, also known simply as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments.