The Influence of Diffusion Fluxes on the Detection Limit of the Jalpaite Copper Ion-Selective Electrode

✍ Scribed by Alberto Zirino; Roland De Marco; Ignacio Rivera; Bobby Pejcic

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 341 KB
• Volume: 14
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/1521-4109(200204)14:7/8<493::aid-elan493>3.0.co;2-c

✦ Synopsis

It has been suggested that electrode dissolution and the concomitant saturation of the electrode×s diffusion layer restricts the detection limit of the jalpaite Cu ion-selective electrode (ISE) to samples with total Cu levels above 10 À6 mol dm À3 [1, 2]. This article will use rotating disk electrode (RDE) data for San Diego Bay seawater and Fick×s law of diffusion to demonstrate that the static commercial Orion Cu ISE (employing a jalpaite membrane) produces a background level of contamination of (2.0 AE 0.5) Â 10 À8 mol dm À3 total Cu, and the reduced thickness of the Orion Cu ISE×s diffusion layer in the presence of hydrodynamic flow [e. g., at an RDE, or in continuous flow analysis (CFA)] lowers the background contamination of Cu to < 10 À9 mol dm À3 . Furthermore, the RDE Cu ISE employing an electrode fabricated using jalpaite precipitated in 80% excess Na 2 S, so as to minimize the presence of occluded and leachable Cu 2 salts and extraneous phases such as silver sulfide [3 ± 5], reveals an improvement in the lower limit of detection compared to the commercial Orion Cu ISE.