2.4.4. COP determination by HPLC
Following the COP extraction process the residue obtained was
dissolved in 250 μL of acetonitrile and then a 20 μL aliquot was
injected in the HPLC system using a filter syringe.
COPs were separated using a C-18 column in isocratic mode. The
mobile phase consisted of 90:10 (v/v) acetronitrile–water using a
1 mL/min flow rate. UV detection was performed simultaneously at
two wavelengths, 205 and 238 nm. Retention times and peak areas
were used for identification and quantification purposes, respectively,
using an external calibration method. Three replicates were carried
out for each sample.