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Photo‐cured ammonium and hydrogen ion selective coated‐wire electrodes used simultaneously in a portable battery‐powered flow injection analyzer
Author(s) -
Alexander Peter W.,
Dimitrakopoulos Telis,
Hibbert D. Brynn
Publication year - 1997
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140091706
Subject(s) - electrode , ammonium , membrane , analytical chemistry (journal) , potentiometric titration , chemistry , inorganic chemistry , ion selective electrode , substrate (aquarium) , standard hydrogen electrode , materials science , selectivity , nuclear chemistry , electrochemistry , chromatography , reference electrode , catalysis , organic chemistry , biochemistry , oceanography , geology
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 < 5 s, 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.