Ehrlich Reagent
Definition
A presumptive colour test for indole-containing compounds: p-dimethylaminobenzaldehyde in HCl/ethanol. Produces purple-violet with LSD, psilocybin, and all tryptamines. Not specific; many non-drug indoles also react.
- Active reagent
- p-dimethylaminobenzaldehyde in HCl/ethanol
- Target
- Indole-containing compounds
- Positive colour
- Purple-violet
- Test type
- Presumptive colour test
Common questions
What limits the evidential value of an Ehrlich test result?+
The reagent is not selective for controlled drugs; it also produces a colour change with a range of non-drug indole compounds naturally present in some plant and biological material, so a positive reaction is treated as presumptive only and must be followed by a confirmatory instrumental method.
How does Ehrlich reagent differ from a general drug spot test like Marquis?+
Marquis reagent targets a broad range of alkaloids and amines through a different chromogenic reaction, while Ehrlich reagent is specifically selected in casework to screen for the indole ring shared by LSD, psilocybin, and tryptamines, a group Marquis does not reliably distinguish.
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