The rapid furfural test is similar to Molisch's test but uses concentrated hydrochloric acid instead of concentrated sulfuric acid and the solution is boiled.
[1] Dilute sugar solution is added to ethanolic 1-naphthol and concentrated hydrochloric acid.
The solution is then boiled and if a purple colour forms within thirty seconds, fructose is present.
If a purple colour does not appear before thirty seconds, glucose is present.
[2] This article about analytical chemistry is a stub.