With the implementation of the European Water Framework Directive, we need reliable, efficent and low cost methods for monitoring the freshwater quality. Pesticide pollutions are not only problematic for the human health but also for aquatic organisms. We developed a multi residue method which allows detecting and quantifying 33 pesticides belonging to five different molecule families. This method was developed for analysis of Solid Phase Extraction (SPE) and Polar Organic Chemical Integrative Sampler (POCIS) extracts. POCIS are particularly interesting in water quality monitoring because of its various advantages. It allows detecting polar chemicals at ultra-trace levels in waters thanks to its high pre-concentration capacity. There is no need of SPE step in laboratory because water extraction is performed directly in the river during POCIS exposure. It is always in the river so short episodic pollutions, like flood events, can not be missed. And the last but not least interest is its simplicity of use. In this study, a particular attention was paid to the study of matrix effects, especially for the POCIS extracts.