Calibrations were made in drinking water, adding 5 10-9-2
10-7MZnEDTA and preconcentrating by a factor of 3-6. They
resulted in linear calibration graphs with correlation coefficients
of at least 0.99 (N > 6). The curves are linear up to concentrations
of 10-5 M. Standard additions of PbEDTA to a Glatt water sample
gave the same slope as that obtained for the addition of ZnEDTA
to drinking water. The correlation coefficient was 0.96 (for n )
8). The repeatability for a river water sample (n ) 4) was (4.36
( 0.26) 10-8 M, and the relative standard deviation was 6%.