Figure 4. Chromatograms from several samples under the described
conditions: (a) effluent of the WWTP Du¨bendorf, EDTA 7.03
10-7 M, no preconcentration. (b) Lake water 1, preconcentration
factor 5.5, EDTA 6.77 10-8 M. (c) Extract of a sediment core from
Lake Greifen at 30 m depth; the two samples are from 1 and 20 cm
depth of the core.