Disposable test plates with tyrosinase and β-glucosidases for cyanide and cyanogenic glycosides Original Research Article

Colorimetric methods for the determination of cyanide and cyanogenic glycosides (amygdalin and linamarin) are developed. In the presence of dissolved oxygen, tyrosinase catalyzes the oxidation of l-tyrosine to dark melanin via red dopachrome. This coloring reaction is inhibited by cyanide, which is added or liberated from a cyanogenic glycoside as a result of hydrolysis catalyzed by a β-glucosidase. This inhibition is utilized to determine cyanide and the cyanogenic glycosides. A spectrophotometric method is quantitative, and its typical dynamic range is 3 μM to 0.1 mM. Test plates that are coated by the films containing tyrosinase, a β-glucosidase, l-tyrosine, and poly(ethyleneoxide) are also prepared as semi-quantitative devices, and their typical dynamic range is 10 μM to 10 mM. This is expected to be an inexpensive, safe, and convenient method for end-users.