This problem is almost without fail caused by a unit conversion error.

ESdat converts the concentrations for all results to a consistent unit per compound.  This is so that results in different units (ie from different labs or from varying environmental standards) can be directly compared.

You should click 'Check Units' on the main ESdat form (next to the import button).  This will show any errors and allow you to add a conversion or change the output units.  Unit conversion errors are also listed when the QA Report is produced.