A presumptive test for barbiturates. The Dille–Koppanyi test reagent has two solutions: a 1% solution of cobalt acetate in methanol, followed by a 5% solution of isopropylamine (CH3CH(CH3)NH2) in methanol. Barbiturates give a reddish-violet colour. This test was invented by James Dille (1928–86) and Theodore Koppanyi (1901–85) 1934.