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Title: Studies on analytical applications of carboxylic acids
Author: Ramsay, Cameron G.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1975
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Following a discussion of -the theoretical concepts involved, the effects of pH and interference of citrate or tartrate in EDTA titrations are. computed from published stability constant data for twenty two common metal cations. Serious interference caused by the simultaneous presence of chromium(ll'l) and tartrate during the titration of cobalt(ll), copper(ll), zinc(ll) and cadmium(ll) with EDTA is attributed to formation of ternary (heteronuclear) tartrate complexes containing chromium(lll) and bivalent metal ion in the ratio 1:1. The properties and conditions for formation of the complexes are described. Among the anomalies described for heteronuclear chromium(lll) citrate complexes formed with bismuth(III), cerium(lll), manganese(ll), tin(n) or lead(ll) is the non-additivity in absorbance in the visible spectra. A structural model for the heteronuclear complexes is advanced to account for the enhanced absorbances and titrimetric errors. Evidence is presented for the existence of many other heteronuclear chromium(lll) citrates and tartrates, and the formation of heteronuclear hydroxycarboxylate complexes is reviewed. Their importance as interferences in analytical chemistry is emphasised. Problems encountered in the complexometric and redox standardisations of chromium(III) solutions are discussed, including formation of inert sulphato complexes and loss of chromium by volatilisation. The novel extraction of chromium(lll) by the high - capacity extractant octanoic acid is described, but applications are severely limited by interference from iron(lll) and nickel(ll). Copper in brass is determined spectrophotoraetrically with citrate, the interference of a heteronuclear copper(ll) citrate complex vath zinc(ll) being counteracted in the preparation of the standards. The fluorimetric determination of traces of succinic acid by synthesis of succinylfluorescein is assessed and modified, and the extension of similar methods to other carboxylic acids is described. The protonation equilibria of succinylfluorescein are investigated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available