What Do TLC Plates Tell You?

How do you read a TLC plate?

In simple terms, this value is an indication of how far up a TLC-plate a compound has wandered.

A high Rf -value indicates that the compound has travelled far up the plate and is less polar, while a lower Rf -value indicates that the compound has not travelled far, and is more polar..

What do TLC results mean?

Thin layer chromatographyThin layer chromatography, or TLC, is a method for analyzing mixtures by separating the compounds in the mixture. TLC can be used to help determine the number of components in a mixture, the identity of compounds, and the purity of a compound.

What causes streaking on TLC plates?

Tailing / Streaks in TLC Plate: Compounds which is basic in nature are often tailing on silica coated TLC plate because silica is acidic in nature so they interact with one another and doing tailing. … Add a different proportion of ammonia solution to solve tailing problem for basic compounds on silica coated TLC plate.

What does TLC tell you about purity?

Thin Layer Chromatography (TLC) is a separation technique requiring very little sample. It is primarily used to determine the purity of a compound. A pure solid will show only one spot on a developed TLC plate. In addition, tentative identification of the unknown compound can be made through TLC analysis.

Why is UV light used in TLC?

Ultraviolet light is often the first visualization technique attempted on an eluted TLC plate because it is nondestructive and rather simple to carry out. If a dark spot is seen with a UV lamp, it is customary to circle the spot with pencil (as in Figure 2.46b), as the spot will be invisible when the lamp is removed.

Which solvent system gave the best results?

Which solvent system gave the best results? The 75% hexane and 25% ethyl acetate gave the best results.

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.

Why silica gel is used in TLC?

Silica gel is a polar adsorbent and being slightly acidic in nature, it has a powerful capacity to absorb basic contents that may be present in the material that needs separation or purification. … Silica gel is acknowledged as one of the most versatile and effective agents that can be used in chromatography.

What will be the result of applying too much compound to a TLC plate not enough?

Protect your skin by wearing gloves. If the TLC plate runs samples which are too concentrated, the spots will be streaked and/or run together. If this happens, you will have to start over with a more dilute sample to spot and run on a TLC plate.

What is the principle of TLC?

What is the principle of TLC? TCL is based on the principle of separation through adsorption type. The separation relies on the relative empathy of compounds towards the mobile phase and stationary phase.

Why is RF less than 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.

How long should you run a TLC plate for?

Question: How Long Should You Run A TLC Plate For? Until The Solvent Front Is About Half Way Up. Until The Solvent Front Is At The Top Of The Plate. 2 Minutes.

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 are the limitations of TLC?

Limitations of TLC Although it is a very simple and convenient technique, one of its limitations is that it cannot tell the difference between enantiomers and some isomers. Another disadvantage of TLC is that in order to identify specific compounds, the Rf values for the compounds of interest must be known beforehand.

Why should you use pencil instead of pen to mark a TLC plate?

Pencil is always used to mark chromatography paper or TLC plates because ink may run and interfere with the chromatogram. … As soon as the paper/plate is taken out, mark the solvent front with a pencil before the solvent evaporates and the front becomes impossible to see.