Optimization of nickel tetracarbonyl generation and nickel in situ trapping within a transversely heated graphite furnace for atomic absorption spectrometry

The efficiency of nickel tetracarbonyl generation and of in situ trapping within a transversely heated graphite furnace was studied. The influence of experimental parameters of the flow injection generation system and in situ collection procedure for atomic absorption spectrometric determination of nickel, i.e. pH of reaction mixture, concentration of sodium tetrahydroborate solution, reaction temperature, concentration of various electrolytes, several ‘heavy metal’ ions and hydride forming elements, trapping temperature, position of introduction capillary and carrier gas flow rates on the overall efficiency were investigated. The acidity of the reaction mixture and the kinetics of carbonyl formation are the limiting parameters of the whole generation procedure. The temperature of the tube, gas flow rate and the position of the capillary are the most critical parameters in trapping nickel from nickel tetracarbonyl. Under optimum conditions, an overall efficiency of approximately 80% was found, evaluating atomic absorption spectrometric signals obtained by carbonyl generation/trapping procedure and by conventional liquid sampling procedure.