1 Determination of sub-ppb epichlorohydrin levels in water by on-line solid phase extraction- 1 liquid chromatography-tandem mass spectrometry 2 Cristina Ripollés, José M. Marín, Francisco J. López, Juan V. Sancho and Félix Hernández * 3 Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 4 Castellón, Spain. Tel.: 964 387366. Fax: 964 387368. 5 * Author for correspondence. E-mail: felix.hernandez@qfa.uji.es 6 7