University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Water -> hydroponic

Citations 1

"Photo-cured Ammonium And Hydrogen-ion Selective Coated-wire Electrodes Used Simultaneously In A Portable Battery-powered Flow Injection Analyzer"
Electroanalysis 1997 Volume 9, Issue 17 Pages 1331-1336
Peter W. Alexander*, Telis Dimitrakopoulos, D. Brynn Hibbert

Abstract: Nonactin and N,N-dioctadecylmethylamine ionophores, each in an epoxydiacrylate polymer, were photo-cured on silver wires (0.8 mm i.d.) and evaluated as ammonium and hydrogen (pH) coated wire electrodes. The photo-cured membranes prepared in this study exhibited excellent adhesion to the metal substrate and improved mechanical strength compared to PVC based membranes. The ammonium electrode exhibited a Nernstian response over a concentration range between 0.01 mM and 100 mM with a detection limit of 0.0005 mM. The ammonium electrode exhibited improved selectivity against most common interfering ions, including potassium compared to previous studies. The hydrogen selective electrode exhibited a near-Nernstian slope of 55.9±0.8 mV change/log a((H+)) between pH 4.0 and pH 11.0 in the steady-state mode. The ammonium and pH sensors each responded quickly reaching 90% of steady-state value in<5s, making these coated wire sensors ideal for flow injection potentiometry measurements. In the FIP mode, both the photo-cured ammonium and pH electrodes exhibited near-Nernstian responses of 49.2±1.0 mV change/activity decade and 50.2±0.4 mV change/log a((H+)), respectively, over a similar concentration range as in the steady-state mode. The photo-cured ammonium and pH electrodes were used simultaneously in the analysis of hydroponic nutrient solutions and waste water samples obtained from a local greenhouse grower in the flow injection potentiometric mode. 29 References
Ammonium pH Electrode Electrode Potentiometry Electrode Electrode Simultaneous analysis Portable Interferences