ETAAS determination of nickel in serum and urine

Methods for the direct determination of Ni in human blood serum and urine by electrothermal atomic absorption spectrometry (ETAAS) are described. Hydrogen peroxide was proposed as matrix modifier, assisting thermal decomposition of proteins during the ashing step. A pyrolysis temperature of 1,200 °C was found to be optimal while 2,100 °C and 2,200 °C were found to be optimal atomizing temperatures for Ni in serum and urine respectively. Calibration was performed by using a calibration curve prepared with aqueous standard solutions of Ni (glycine must be used as modifier for Ni in aqueous solutions). The limits of detection, defined as the blank values plus 3 times the standard deviation of the blank values, were 0.2 µg/L for both serum and urine samples. Relative standard deviations for serum samples with concentrations of Ni in the range 0.5–2 µg/L were 10–15% and for urine samples with Ni concentrations in the range 0.5–2.5 µg/L were 8–10%.