Visualising Reagent
Definition
A spray or dip that converts a colourless TLC spot into a coloured or fluorescent one so the chemist can locate it. Marquis turns opioids purple and amphetamines orange; Dragendorff turns alkaloids orange-red; ninhydrin turns amino acids violet. The reagent panel is what makes TLC a presumptive identification rather than a generic separation.
Related terms
- Mobile Phase
- The solvent or mixture that flows over the stationary phase and carries analytes along. Polarity, viscosity and volatility set the separation; switching...
- Resolution (Rs)
- Rs = 2(tR2 − tR1) / (W1 + W2). Above 1.5 means baseline separation; below 1.0 means peaks overlap and quantitation is...
- Rf Value
- The retention factor, defined as the distance the spot travels divided by the distance the solvent front travels on the same plate....
- Stationary Phase
- The immobile material the mixture flows past. In paper it is water inside cellulose fibres; in classical column work and TLC it...
- Theoretical Plate Count (N)
- A measure of column efficiency, N = 16(tR/W)² for a column peak, where tR is retention time and W is peak width...
Explained in
- Chromatography Fundamentals: Paper, Column and TLCA spray or dip that converts a colourless TLC spot into a coloured or fluorescent one so the chemist can locate it. Marquis turns opioids purple and amphetamin...