Electrochemical reduction of chloridazon at mercury electrodes, and its analytical application.
The electrochemical behavior of the herbicide chloridazon, I (pyrazon), at different pH is described. The electrode reaction (one wave in acidic media and another in alkaline media), investigated using direct current and pulse voltammetry, controlled-potential coulometry, and HPLC-MS, is a combination of the electroreduction (two-electron in the first step) and a kinetic process as a result of which simple compounds (HCl, NH3) are released and, moreover, a five-membered pyrrole cycle is formed in strongly acid media. Products of the kinetic reaction are further reducible. The dissociation constant of I, pKa = 2.96, was found spectrophotometrically. Fast-scan differential pulse voltammetry (FSDPV) was used for determination of I; the detection limit was 2.7 x 10(-8) mol L(-1) (0.006 microg L(-1)) at pH 2.3. Chloridazon was determined in spiked drinking and river water.
Zimpl
M
M
Department of Analytical Chemistry, Palacký University, Olomouc, Czech Republic.
Kotoucek
M
M
Lemr
K
K
Veselá
J
J
Skopalová
J
J
D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D005618:Fresh Water / Q000032:analysis; D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008628:Mercury; D010084:Oxidation-Reduction; D011724:Pyridazines / Q000032:analysis / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000032:analysis; D014881:Water Supply / Q000032:analysis
D006540:Herbicides; D011724:Pyridazines; C005586:pyrazon; D008628:Mercury