Na+-selective nasicon electrode used as potentiometric and amperometric sensor in a wall-jet FI system
✍ Scribed by Ionel C. Stefan; Ionel C. Popescu; Pierre Fabry
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 197 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0895-7533
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✦ Synopsis
A Na ם -selective NASICON-membrane electrode (Na ם -SNME) was tested in a single-line flow-injection (FI) system, both in potentiometric and amperometric operational modes. The Na ם -SNME was homemade, using a NASICON pellet and an Ag/ AgCl, 0.02 M NaCl internal reference electrode, and it was inserted into a wall-jet electrochemical cell. For a 28 lL sample loop and an injector-cell connecting tube (i.d. 0.5 mm) as short as possible, the optimum experimental conditions (flow rate, jet-nozzle membrane distance, and applied potential value) were established. The FI results obtained in the steady-state potentiometric operational mode confirmed those previously reported for batch measurements: lower limit of the linear range 4 ן 10 4מ M; slope 58.6 mV/pNa; detection limit 2 ן 10 4מ M; selectivity coefficients K NaK ס 2 ן 10 2מ , K NaLi ס 1.6 ן 10 2מ , K NaH ס 3.8. For FI amperometric operational mode, the analytical parameters were better than those corresponding to the potentiometric one: detection limit 10 5מ M; selectivity coefficients K NaK ס 7.1 ן 10 3מ , K NaLi ס 7.6 ן 10 3מ , K NaH ס 3.1; a linear dependence between the current intensity and the Na ם -concentration in the low concentration domain