Narration : 16. Thin Layer Chromatography
- Firstly add a small amount of the developing solvent into a wide-mouth bottle.
- Close the cap and wait a little until the bottle is saturated with the solvent vapor.
- Take a little of a sample with a microspatula and dissolve it in a small amount of an appropriate solvent.
- In order to keep the TLC plate clean, hold the edge with tweezers.
- Place the plate so that the silica gel layer faces upward.
- Draw the starting line lightly with a pencil at a few mm above the edge of the plate. Draw cross marks on the line as starting points.
- Take the sample solution with a capillary, spot the solution lightly on one of the starting points. The spot should be less than 2 mm in diameter. Don't apply a lot of the solution at one time as it will blot. Then, dry the spot with a dryer if necessary. Repeat this operation a few times to concentrate the sample into a small spot.
- Hold the upper end with tweezers. Place it in the bottle so that the bottom is immersed in the solvent, and the top is leaned against the wall. Then, close the cap. During the development, don't open or move the bottle.
- Sample compounds move on the TLC plate along with the developing solvent. Less polar compound is adsorbed weakly by the silica gel and moves fast. On the other hand, more polar compounds are absorbed strongly and move slowly.
- Stop the development when the front reaches a few mm below the edge of the plate. Take out the TLC plate and immediately mark the front line with a pencil.
- Wait for the solvent to evaporate or dry the plate with a dryer.
- Turn on the UV lamp. Trace the outlines of the spots detected with UV ray with a pencil.
- Use safety glasses for protection from UV ray when you use a UV lamp for detection.
- Measure distance a from the starting point to the center of the spot and distance b from the starting point to the front of the developing solvent. Calculate Rf values by dividing a by b.