Electrocatalytic amperometric determination of amitrole using a cobalt-phthalocyanine-modified carbon paste electrode.
Cobalt-phthalocyanine-modified carbon paste electrodes are shown to be excellent indicators for electrocatalytic amperometric measurements of triazolic herbicides such as amitrole, at low oxidation potentials (+0.40 V). The detection and determination of amitrole in flow injection analysis with a modified carbon paste electrode with Co-phthalocyanine is described. The concentrations of amitrole in 0.1 M NaOH solutions were determined using the electrocatalytic oxidation signal corresponding to the Co(II)/Co(III) redox process. A detection limit of 0.04 microg mL(-1) (4 ng amitrole) was obtained for a sample loop of 100 microL at a fixed potential of +0.55 V (vs. Ag/AgCl) in 0.1 M NaOH and a flow rate of 4.0 mL min(-1). Furthermore, the modified carbon paste electrodes offers reproducible responses in such a system, and the relative standard deviation was 3.3% using the same surface, 5.1% using different surface, and 6.9% using different pastes. The performance of the cobalt-phthalocyanine-modified carbon paste electrodes is illustrated here for the determination of amitrole in commercial formulations. The response of the electrodes is stable, with more than 80% of the initial retained activity after 50 min of continuous use.
Departamento de Química Analítica y Análisis Instrumental, Facultad de Ciencias, Universidad Autónoma de Madrid, Spain. manuel.chicharro@uam.es
Manuel
M
Chicharro
Antonio
A
Zapardiel
Esperanza
E
Bermejo
Mónica
M
Moreno
Elena
E
Madrid
D000640:Amitrole / Q000032:analysis* / Q000592:standards; D003035:Cobalt / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D006540:Herbicides / Q000032:analysis* / Q000592:standards; D007211:Indoles; D009942:Organometallic Compounds; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014230:Triazoles / Q000032:analysis
D006540:Herbicides; D007211:Indoles; D009942:Organometallic Compounds; D014230:Triazoles; C063633:cobalt phthalocyanine; D003035:Cobalt; D000640:Amitrole