The Chen-Kao test is performed by creating an acidic solution of the compound to be tested and adding dilute Copper (II) Sulfate and Sodium hydroxide solutions.<br />The procedure is as follows:
#Place small amount of material to be tested on a spot plate.
#Add 2 drops of reagent A
#Add 2 drops of reagent B
#Add 2 drops of reagent C
#A violet color indicates presence of ephedrine or pseudoephedrine
*Reagent A - 1% (vol/vol) aqueous acetic acid solution
*Reagent B - dissolve 1g Copper(II) sulfate in 100ml water
*Reagent C - dissolve 8g of NaOH in 100ml of water (that is 2N NaOH solution)
Further, the coordination complex might be extracted with organic solvent like diethyl Ether or n-butanol (see Table II), as proposed in the literature, which provides additional confirmation of the original results, but no further differentiation.  This modification is not included in the UN Precursor Test Kit and other spot tests alike. In order to further differentiate between ephedrine enantiomers - ephedrine, pseudoephedrine and other ephedrine-related compounds, Simon’s test (with acetaldehyde) and Simon’s test (with acetone) are used. (see Table III)