Metalloporphyrin-based acetate-selective electrodes as detectors for enzymatic acetylcholine determination in flow-injection analysis system.
In this work two Zr(IV)-porphyrins were tested as potential acetate-selective ionophores. It is shown that these compounds show increased selectivity towards acetate ion, with selectivity sequence: Cl- < NO3- < SCN- < ClO4- < acetate- < F-, when incorporated into polymeric ion-selective membranes. Among tested ionophores, Zr(IV)-tetra(tert-butylphenyl)porphyrin was found to be the best in terms of response time (20 s) and lower detection limit (2 x 10(-4) M acetate-). Designed electrodes were used as detectors in flow-injection analysis system for acetylcholine determination. Enzymatic hydrolysis was used to generate acetate ions from acetylcholine, employing acetylcholinesterase immobilized on Amberlite. The optimization of enzymatic reactions and flow-injection analysis system configuration were performed and enzyme immobilization procedures have been evaluated. It is shown that resulting flow-injection system exhibits good working parameters, such as reproducibility (standard deviation < or = 3.5%), sampling rate (60 samples per hour) and lifetime (over a week).
Górski
Łukasz
Ł
Warsaw University of Technology, Faculty of Chemistry, Department of Microbioanalytics, 00-664 Warsaw, Poland. lukegor@ch.pw.edu.pl
Mroczkiewicz
Monika
M
Pietrzak
Mariusz
M
Malinowska
Elzbieta
E
D000085:Acetates / Q000737:chemistry*; D000109:Acetylcholine / Q000032:analysis*; D017022:Flow Injection Analysis / Q000295:instrumentation; D017736:Ion-Selective Electrodes; D008665:Metalloporphyrins / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods*; D015203:Reproducibility of Results; D015032:Zinc / Q000737:chemistry
D000085:Acetates; D008665:Metalloporphyrins; D015032:Zinc; D000109:Acetylcholine