Mercury chloride (Hg+II), methylmercury chloride (MeHg+I), ethylmercury chloride (EtHg+I), and phenylmercury chloride (PhHg+II) have been chosen as model compounds. UV-photochemical cold mercury vapor generation was used as a derivatization step between high performance liquid chromatography on reverse phases (RP-HPLC) and atomic absorption spectrometry with quartz detection tube.