Determination and data evaluation of copper complexation by organic ligands in sea water using cathodic stripping voltammetry at varying detection windows
✍ Scribed by Constant M.G. van den Berg; John R. Donat
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 987 KB
- Volume
- 257
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
Pubhshed data of trace metals m sea water show very large drfferences In strength of organic complexatlon These differences are mcompatlble wtth the expected order of complexatlon by reversible and nonspectitc complexmg hgands Comparison revealed a hnear relatlonshlp between the detection wmdows of the analytIca techmques and the detected metal complexatlon A possible explanation for this relationship 1s that the apparent differences between organic complexatlon of different metals are artifacts when the analytical techmques detect only one or two of many complexmg bgands of greatly varying complexmg ability m the natural water samples Detailed complexahon measurements of copper m samples from the Sargasso Sea and the North Sea were camed out at several detection windows using cathodic strlppmg voltarmnetry and confirmed the presence of several complexmg hgands The detected hgand concentration was found to decrease wth mcreasmg magmtude of the detection wmdow, whereas the conditional stability constant was found to Increase The overall effect was that the degree of metal complexatlon [(ZacuL) -I + 11, where L IS the number of n coeffk~ents, mcreased Hrlth the detection wmdow whereas the complexatlon due to the mdlvldual hgands (cy,,) increased untd a malumum had been reached when the hgand concentration was approximately equal to the metal concentration whereafter it decreased at very high detection windows An additional observation was that the dlssoclatlon rate of organically complexed copper m sea water 1s very slow the process requlrmg more than 1 h to reach eqmhbrmm wrth an added competing hgand The complexation data were used to estimate the total number of hgands and the range of condItiona stability constants The overall complexation of copper m sea water was calculated givmg values for pCu between 13 5 and 1.5 4