The non-linear response of PCBs and OCPs is a well-known problem when
performing analysis on GC/ECD. Thus, three different non-linear calibr
ation functions were tested experimentally using 12 calibration soluti
ons (1-200 ng ml(-1)), six of them used for calibration and six of the
m for testing the reliability of the function. The piecewise calibrati
on was chosen as the most robust for all compounds in question, while
the power function fitted best for all except two compounds; the secon
d-order function showed problems at the very low concentration levels.
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