Determination of zinc in blood serum by electrothermal atomic absorption spectrometry with matrix modification

Zinc determination in serum microsamples can be treated by graphite furnace atomic absorption spectrometry. To reduce the contamination risks and to obtain results as right as possible, the serum has been twenty fold diluted instead of 100-fold diluted (rate frequently obtained). In these conditions, the use as diluent of a 1% Triton X 100 solution or of a 33.7 mmol/l magnesium nitrate did not allow to obtain exact results. Yet, with an 37.8 mmol/l ammonium phosphate solution, the results given by the direct calibration on an aqueous calibration curve were in good accordance with those found with a recommended flame atomic absorption spectrometry method. The within-run RSD of our method was 2.6%.