TLC Stains/Dips

• Ultraviolet: Look at the plate under the light first when working with compounds with conjugated double bond systems.
• Iodine: Shake with powdered I2. You can then heat the plate to remove the iodine stain, and use a liquid TLC stain as usual.
• Anisaldehyde (great for carbonyl groups). Dip, dry and heat on hot plate to develop.
  1. EtOH (200 mL); H₂SO₄ (10 mL); p-anisaldehyde (10 mL)
  2. EtOH (250 mL); H₂SO₄ (2.5 mL); p-anisaldehyde (15 mL)
  3. EtOH (425 mL); H₂SO₄ (16 mL); p-anisaldehyde (8-12 mL); HOAc (5 mL): mix everything but p-anisaldehyde, which you add when the mixture has cooled to rt. Store refrigerated. If you add the anisaldehyde to the warm solution, it will turn bright pink and will not stain TLC plates properly.
• Ceric Ammonium Molybdate (great for hydroxy groups). Dip, dry and heat on hot plate to develop.
  1. Ce(SO₄)₂ (cerium sulfate: 5.0 g);(NH₄)6Mo₇O₂₄·4H₂O (ammonium molybdate: 25.0 g); conc. H₂SO₄ (50 mL); H₂O (450 mL)
  2. Ce(NH₄)₄(SO₄)₄·2H₂O (ceric ammonium sulfate: 4.0 g); ammonium molybdate (10 g); conc. H₂SO₄ (40 mL); H₂O (360 mL)
  3. Ceric ammonium sulfate (0.5 g); ammonium molybdate (12 g); conc. H₂SO₄ (15 mL); H₂O (235 mL)
• Ninhydrin (great for amines): Dissolve 0.3g ninhydrin in 100 ml of n- butanol; add 3 ml AcOH.
• Phosphomolybdic Acid (generally useful): 10% in Ethanol. Dip, dry and heat on hot plate to develop.
• Potassium Permanganate (generally useful). Dip, dry and heat on hot plate to develop.
  1. KMnO₄ (1g); Na₂CO₃ (2g); H₂O (100 mL)
  2. KMnO₄ (3g); K₂CO₂ (20g); 5 percent NaOH (5 mL); H₂O (300 mL)

For more information, see Stains for Developing TLC Plates (.doc)

More on TLC stains and their applications