Kinetic spectrophotometric determination of nanogram amounts of cyanide.
A sensitive kinetic method for determination of nanogram amounts of cyanide is reported. It is based on the measurement of the induction period imposed by cyanide on the copper(II)-catalysed oxidation of 3-hydroxybenzaldehyde azine (3-OHBAA) by potassium peroxydisulphate. Kinetic data are recorded spectrophotometrically at 465 nm, the maximum absorption wavelength of the oxidation product of 3-OHBAA. From the kinetic study and other experimental tests it may be concluded that the cyanide ion undergoes copper(II)-catalysed oxidation during the induction period. The calibration plot is linear in the range 150-600 ng/ml cyanide and the detection limit is 50 ng/ml. The precision of the method, expressed as the relative standard deviation, is 3.2% for 350 ng/ml cyanide. Good recoveries are obtained in applying the method to analysis for cyanide in water samples.
Velasco
A
A
Department of Analytical Chemistry, Faculty of Sciences, University of Córdoba, 14004 Córdoba, Spain.
Silva
M
M
Valcarcel
M
M