On line separation and sequential determination of trace amounts of heavy metals in biological materials by flow injection inductively coupled plasma atomic emission spectrometry

A how injection inductively coupled plasma atomic emission spectrometric method for the sequential determination of trace amounts of heavy metals (Cd, Co, Cu and Zn) in biological samples is described based on the complexation of the metal ions with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide and its subsequent on-line extraction into isobutyl methyl ketone. A systematic study was performed to determine the optimum conditions for the continuous extraction of the metals. Detection limits for Cu, Co, Zn and Cd ranged from 1.1 to 23.0 ng ml(-1) with precision varying from 1.2 to 3.7% relative standard deviation at 100 ng ml(-1). These values were obtained under simultaneous multi-element conditions. The effect of various foreign ions on the determination of these metals by the proposed method was examined under the optimum working conditions. The tolerance limits found showed that they can be determined in the presence of a variety of ions including most of those that commonly occur with them in natural samples. Accuracy and matrix interference were confirmed by standard additions and use of certified reference materials.