Organohalides and Pesticides

MPc complexes have been employed as catalytic components in microemulsions and as composite films for the analysis of phenols and organohalides. Rusling and coworkers reported on FePc/DDAB, CuPc/DDAB, CuTSPc/DDAB, NiPc/DDAB, NiTSPc-DDAB, ZnPc/DDAB or ZnPc/CTAB surfactant films , and Jiang et al. on CoTSPc/DDAB for use in catalyzed reduction of trichloroacetic acid (TCA) and other organohalides. The catalytic reduction of TCA was more efficient in the acetonitrile/water solvent mixture than in the microemul-sions . Table 7.1 shows that lower potentials were observed for catalysis of TCA on surfactant films containing NiPc complexes than for the corresponding CuPc species. 

Rusling and coworkers also studied debromination and dechlorination of organohalidess by MPc in microemulsions - . Reductive dechlorination on clay surfactant films containing MPc complexes was better on CoPc compared to FePc, since the former remained intact in the film while the latter decomposed . The order of the catalytic activity was CoPoFePoZnPc. Co Pc species was implicated as an intermediate in the catalytic process. The high activity of CoPc was correlated with an inner sphere mechanism, while the low activity of ZnPc 

CoPc modified carbon paste electrodes were reported by Chicharo et al. to show good catalytic activity towards the measurement of triazolic herbicides sueh as amitrole at low oxidation potential (+0.4 V, Table 7.1) in basic media, a detection limit of 0.04 jig mL was obtained using a injection system . A screen-printed carbon electrode which was impregnated with CoPc electrocatalyst, was employed in conjunction with acetylcholinesterase by Hartley and Hart for the reduction of organophosphate pesticides The detection limits were of the order of 10 and 10  

Using CuTSPc as component of the microemulsion lowered the overpotential for the reduction of o-chlorophenol by 1 V, hence showed promise for catalytic decomposition of DDT .  

Reports on the use of monomeric MPc complexes for the electrocatalysis of phenols are rare, hence the use of some polymeric MPc complexes will be included in this section. Biosensors based on enzymes have been developed for many electrochemical analyses. The use of MPc complexes as part of the enzyme improves the sensitivities of the biosensors. Ozsoz et al. used CoPc monomer dispersed in mushroom tissue electrode as a catalyst for the analysis of phenolic compounds The enzymatic reaction between mushroom and the phenolic compounds was coupled with the catalytic activity of CoPc. The CoPc dispersed electrodes gave shorter response times and lower potentials compared to conventional tissue biosensors . 

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