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The biocides cybutryne, terbutryn and dichlorvos, and the pesticides aclonifen, bifenox, quinoxyfen are new priority substances of Water Framework Directive of the European Union. The article describes the development and validation of a liquid chromatographic-tandem mass spectrometry method (LC-MS/MS) for the simultaneous determination of the six organic pollutants. The proposed method included an automated solid phase extraction (SPE) step using polymeric cartridges (OASIS HLB) followed by LC-MS/MS, under multiple reactions monitoring mode (MRM). Organic contaminants were analyzed in surface water samples from the Danube River and its tributaries (Arges River, fin River, and Olt River). Terbutryn and dichlorvos were below the limits of detection (LODs) in all samples. The surface water samples were found to be contaminated by quinoxyfen (0.4-3.5 ng/L), aclonifen (1.21-8.4 ng/L), bifenox (1.8 ng/L), below environmental quality standards. The pesticide detected with the highest frequency was quinoxyfen. The highest concentrations of pesticides were recorded in Olt River (aclonifen 8.4 ng/L) and in Danube River in Turnu Magurele sampling point (quinoxyfen 3.5 ng/L).