What are the spots on a TLC plate?
To use TLC in this manner, three lanes are spotted on a TLC plate: one for the limiting reactant, one for the co-spot, and one for the reaction mixture. The goal is to note the disappearance of the limiting reactant in the reaction mixture lane and the appearance of a new product spot.
What does 2 spots on a TLC plate mean?
Ideally, each compound in a mixture will produce a distinct spot so a sample with two compounds will give two different spots, and so on. An important property of any compound, is its Rf-value (retention factor). In simple terms, this value is an indication of how far up a TLC-plate a compound has wandered.
Which stain would you choose to identify amines on a TLC plate?
Stains for TLC Plates
| Name | Visualization of… |
|---|---|
| Ninhydrin (Indanetrione Hydrate) | Amino Acids Amino Sugars Amines |
| Phosphomolybdic Acid (PMA) | Universal stain Very effective against dilute sample |
| N.B.: Can be used for detection of alcohols, amines, sulfides and mercaptans groups when gently heated. |
What is solvent front?
In chromatography, the solvent front is the position on the TLC plate indicating the furthest distance traveled by the developing solvent (or eluent)
What causes TLC streaking?
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 does thin layer chromatography tell you?
Thin 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 are two common methods of visualizing the spots of compounds on a TLC plate?
There are two common methods available for visualizing the spots on the tlc plate. If the compounds under study contain a chromophore (ie an aromatic compound), the plate may be placed under an ultraviolet lamp. The spots will show as dark circles on a fluorescent background.
What are Visualising agent?
Specific spray reagents or detecting agent or visualising agent are used to find out the nature of compound. Example. Ferric chloride – for phenolic compound and tannins. Ninhydrin in Acetone – for amino acids.
What is iodine chamber?
An “iodine chamber” can be created by adding a few iodine crystals to a TLC chamber, or by adding a few iodine crystals to a chamber containing a portion of powdered silica or alumina (Figure 2.33a). The coloration occurs because iodine forms colored complexes with many organic compounds.
What stains are used in thin layer chromatography to visualize the plates?
The staining of a TLC plate with iodine vapor is among the oldest methods for the visualization of organic compounds. It is based upon the observation that iodine has a high affinity for both unsaturated and aromatic compounds.
What do you need to make a TLC spotter?
TLC spotters are made from glass capillary tubes, available from most suppliers of chemicals or glassware. A capillary tube with two open ends will create two TLC spotters. A capillary melting point tube – with one end closed – will create one TLC spotter. To Make TLC Spotters (Fig. 1)
How big should a spot be on a TLC plate?
It is better to touch the spotter to the TLC 2–3 times for short amounts of time (> 1s) than to hold it against the plate for a longer time. The resulting spot should be 1–2 mm in diameter. Once you have enough sample deposited on the TLC plate, touch the spotter to a piece of tissue to remove any remaining sample.
Can a TLC plate get clogged with silica?
With reuse, the tips of TLC spotters can get damaged or clogged with silica from the TLC plate. If this occurs, the end of the tip can be snapped off by bending. The end should be as flat as possible as jagged edges can lead to overloading and unsymmetrical spots on the TLC plate.
Why do you use a TLC spotter instead of Pasteur?
This prevents overloading and helps achieve an accurate and clear TLC in preparation for running a full column. TLC spotters are easy to make and are a much better alternative to trying to use a Pasteur pipette which have a wider opening and so create a larger spot on the TLC – no matter how careful you are.