Chemical amplification of the signal in ion-selective potentiometry: indirect determination of Al(III) and U(VI) by steady-state and flow-injection potentiometry using a copper ion-selective electrode
✍ Scribed by M. Neshkova; E. Pancheva; J. Fucsko; G. Nagy; E. Pungor
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 753 KB
- Volume
- 259
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
The posslbdltles for the mdlrect steady-state and flow-mJectlon determmatlon of Al(III) and U(W) mth a copper Ion-selectwe electrode were studled The method 1s based on the replacement reaction between the determmand and a CuLz-buffer system [L = oxalate (Ox) or malonate (Mall] at a pH of 5 4 fixed urlth acetate buffer Chemical amphflcatlon of the potentlometrlc slgnal was observed owmg to the stolchlometIy of the followmg overall replacement reactlon 2CuL, + M = ML, + 2CuL
It IS manifested by a double-Nernstlan slope of the C&I) electrode function (60 mV per decade) The concentration range for Al determmatlons IS from 1 35 to 216 mg 1-l and for uramum from 14 to 2142 mg I-' Good reproduclbdlty and high preclslon were achieved Metal ions that do not form carboxylate complexes or form less stable complexes than CuOx2 (e g , Ca, Sr, Ba, Cd, Zn) do not interfere Special maskmg procedures allowing the determmatlon of Al(II1) m the presence of Fe(II1) and U(W) m the presence of Th(IV) were developed and experimentally tested A flow-mJectlon version of this approach was elaborated which preserves the mam beneficial features of the steady-state mode The proposed approach could be extended to other mdlrect determmatlons, and seems very promlsmg for future wider apphcatlon of Ion-selective electrodes as detectors m flow systems