Abstract This paper reports the utilization of solid phase extraction and the reversed-phase high-performance liquid chromatography (RP-HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2-(2-quinolinylazo)-5- ...