Automated, high-precision coulometric titrimetry part I. Engineering and implementation

✍ Scribed by Kenneth W. Pratt

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 824 KB
• Volume: 289
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(94)80095-2

✦ Synopsis

Automated constant-current coulometry, based on Faraday's Laws, achieves uncertainties (relative standard deviation) of less than 1 part in 20000 without chemical standardization. It is applicable to acid-base, redox, and precipitation titrations of high-purity compounds and solutions. Automation of the technique pennits unsupervised operation and reduces operator-dependent errors. Initial setup and sample introduction are the sole manual steps. Each assay consists of a main titration at high, constant current, bracketed by the initial and final endpoint routines, each at a lower current. The coulometric assay is analogous to a conventional titration in which two different concentrations of the titrant are used to attain optimum accuracy. The initial endpoint determination corresponds to the blank determination in a classical titration. Each titration includes a statistical analysis of the random and systematic uncertainties associated with the analysis. Individual steps in the procedure are performed by a hierarchical series of subroutines to reduce program complexity. Results are presented for K,Cr,O,, benzoic acid, and solutions of strong acids.