Optimisation of a solid-phase microextraction/HPLC/Diode Array method for multiple pesticide screening in lettuce

► Optimization of a SPME/HPLC-DAD method for multiple pesticide screening in lettuce. ► Response surface methodology based on central composite design was used. ► NaCl %, pH and extraction time were key variables in the optimization process. ► Monitorization of pesticides to study the dissipation during lettuce days to harvest.