Hyphenation of high performance liquid chromatography with sector field inductively coupled plasma mass spectrometry for the determination of ultra-trace level anionic and cationic arsenic compounds in freshwater fishElectronic Supplementary Information (ESI) available: analytical figures of merit obtained with a standard set-up, the LOD for the high resolution mode, LODs reported by other authors and tissue concentrations for the Northern pike. See http://www.rsc.org/suppdata/ja/b3/b304890j/