Zwikker / Dille-Koppanyi Reagent
Definition
Cobalt salt (nitrate or acetate) plus isopropylamine. Violet to blue-violet colour with barbiturates. Workhorse barbiturate screen since the 1940s.
- Reagents
- Cobalt nitrate or acetate plus isopropylamine
- Target class
- Barbiturates
- Colour response
- Violet to blue-violet
- In use since
- 1940s
Common questions
Is a positive Zwikker/Dille-Koppanyi reaction confirmatory?+
No. It is a presumptive colour test used for rapid screening, and a violet response must be followed by a confirmatory instrumental method such as GC-MS before a barbiturate identification is reported.
Can other compounds give a similar colour with this reagent?+
Yes. The cobalt complex reaction is not fully selective for barbiturates, and certain other drug classes or matrix components can produce comparable colour shifts, which is why confirmatory testing is required.
Related terms
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