The Zwikker reagent is used as a simple spot-test to presumptively identify

barbiturates Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as ...

. It is composed of a mixture of two solutions. Part A is 0.5 g of copper (II) sulfate in 100 ml of

distilled water Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, dis ...

. Part B consists of 5%

pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakl ...

(v/v) in chloroform. One drop of each is added to the substance to be tested and any change in colour is observed. The test turns

phenobarbital Phenobarbital, also known as phenobarbitone or phenobarb, sold under the brand name Luminal among others, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of ep ...

pentobarbital Pentobarbital (previously known as pentobarbitone in Britain and Australia) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment o ...

and

secobarbital Secobarbital (as the sodium salt, originally marketed by Eli Lilly and Company for the treatment of insomnia, and subsequently by other companies as described below, under the brand name Seconal) is a short-acting barbiturate derivative drug tha ...

light purple. Tea and tobacco turn yellow-green. The test's lack of specificity and tendency to produce false positives means it is not widely used for presumptive drug testing, although it does still play a role as a

thin layer chromatography Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of an inert substrate such as glass, plastic, or aluminium foil, which is coated with a t ...

stain. It is named after the Dutch scientist Cornelis Zwikker.

References

Chemical tests Analytical reagents Drug testing reagents {{chem-stub

See also

References