A fast method for separation of iron, nickel, lead, and zinc from water matrices prior to their atomic absorption spectrometry (AAS) is described. The separation and preconcentration of metals was performed by precipitate colloid flotation with cobalt(III) hexamethylenedithiocarbamate, Co(HMDTC)(3), as a new collector. The optimal conditions for flotation of each analyte by Co(HMDTC)(3) were, determined. After flotation separation analytes were analyzed by flame atomic absorption spectrometry (FAAS) or electrothermal atomic absorption spectrometry (ETAAS) depending of their concentrations in the water sample. The results of AAS analyses are,compared with those obtained by inductively coupled plasma-atomic emission spectrometry. The limit of detection of analytes was determined 0.838 mug/L for iron and 1.105 mug/L for zinc using FAAS and 0.129 mug/L for lead and 0.113 mug/L for nickel by ETAAS.