Ultratrace molybdenum determination in biological samples by graphite-furnace atomic-absorption spectrometry

A method is described for molybdenum determination in human serum at sub-ng/ml levels by graphite-furnace atomic-absorption spectrometry. Sample preparation involves a nitric acid digestion, chelation with benzohydroxamic acid and extraction into hexanol. A detection limit of 0.1 ng/ml and a characteristic concentration of 0.18 ng/ml for 1% absorption can be achieved. The effectiveness of the method has been demonstrated by analysis of unspiked and spiked human serum, standard reference materials, and comparison with the results obtained by inductively-coupled plasma atomic-emission spectroscopy.