The invention relates to a method for the detection of
cyanide ion, comprising the steps of: adding
copper ions into a solution to be tested to obtain a
copper ion-containing solution having the concentration of 5.0*10-5.0*10mol / L, then adding
copper reagent of
sodium diethyldithiocarbamate into the copper
ion-containing solution, wherein, if the color of the solution is not changed after the addition of the copper
reagent, the fact that the solution to be tested contains
cyanide ion is represented, and if the color of the solution is changed after the addition of the copper
reagent, the solution to be tested contains
cyanide ion having the concentration less than 6.0*10mol / L or contains no
cyanide ion. The invention is applicable to
aqueous solution system, visible to naked eyes, low in price and
detection limit, and reversible in phenomenon. Change of the color of the
system is
observable to naked eyes by means of the addition of
cyanide ion of 1.0*10, the larger the concentration is, the more obvious the change of the color takes place, and the color is gradually changed from dark yellow into transparent color. With good reproducibility when pH is equal to 6-10, the solution can be used for the detection of minim-
cyanide ion and can be practicably applied in aspects of drinking water, food,
environmental protection, etc.