Stains for TLC

Although the recipes can be found on internet, here are some I used in the lab.

Ceric Ammonium Molybdate (CAM): This stain is prepared by dissolving 2.5 g of (NH4) 6-Mo7O24 and 1.0 g Ce(SO4)2 in 90 mL of water and 10 mL of conc. H2SO4. The plate is developed by heating on a hot plate. This stain chars blue and is good for polyhydroxylated compounds.


Potassium Permanganate: This stain is prepared by dissolving 3 g of KMnO4 and 20 g of K2CO3 in 5 mL of 5% NaOH and 300 mL of water.

p-Anisaldehyde: This clear tan stain is prepared by dissolving 0.7 mL of p-anisaldehyde in 250 mL of EtOH containing 9.5 mL of conc. H2SO4 and 2.7 mL of acetic acid. The plate is developed by heating on a hot plate. This stain chars lavender and is good for oxygenated compounds.

Sometimes, I found PMA is the only one that can show me the spot.

Phosphomolybdic acid (PMA): This green-yellow stain is prepared by dissolving ~3-4 g of PMA in 100 mL of EtOH. The plate is developed by heating on a hot plate. PMA is the most commonly used stain for organic materials, since it reacts with a wide variety of functional moieties. The spots are usually black against a yellow-green background. PMA is also effective with extremely dilute reaction samples and in this regard can be used semi-quantitatively.