ANALYSIS OF TITRATION CURVES OF LAKE TJEUKELMEER WATER WITH CU(II) - IDENTIFICATION OF THE FORMATION OF MORE THAN 2 GROUPS OF DIFFERENT COMPLEXES

The results for direct titration of Lake Tjeukemeer water with Cu(II) are interpreted by using both the van den Berg-Ruzic and Scatchard plo ts. The use of a new method for correction of asymptote at higher addi tions of metal proposed by Ruzic and Pecar has been illustrated with t hese titration data. The analysis of reduced titration data obtained b y extraction of the equation for weaker complexes from the original ti tration data has been proved to be a very powerful method by which the accuracy of determining complexation parameters for higher energy bin ding sites can be checked. The following stability constants (K-i) and complexing capacities (L-i) are reported: K-1 = 1.661 . 10(4) dm(3) m ol(-1), L-T1 = 7.978 . 10(-5) mol dm(-3) K-2 = 3.014 . 10(5) dm(3) mol (-1), L-T2 = 1.278 . 10(-5) mol dm(-3) K-3 = 1.588 . 10(7) dm(3) mol(- 1), L-T3 = 5.432 . 10(-6) mol dm(-3) K-4 = 6.432 . 10(8) dm(3) mol(-1) , L-T4 = 5.996 . 10(-7) mol dm(-3) High concentration of organic matte r in the Lake enabled direct titration with Cu(II) in a wide range of concentrations, so that four different binding strengths could be dete cted from the titration data.