Measurement uncertainty of Pb, Cd and Ni determination in human hair by electro thermal atomic absorption spectrometry

Today, in developing countries like iran heavy metals are present everywhere which threatens the health of the people . the analysis of human hair is useful in monitoring the levels of certain trace clements in the body and assessing heavy metal s environmental exposure. in the present work, we propose uncertainty estimation for the analytical results we obtained from determination of cadmium, lead and nickel in human hair by electro thermal atomic absorption spectrometry (etaas) . prior to analysis, hair samples were washed with 1% (w /v) sodium diethyldithiocarbamate (ddtc), and 0.1m hcl. the hair samples were digested afterward in a mixture of hno3, and h2o2. to estimate the uncertainty of analytical result obtained, we propose assessing trueness by employing spiked sample. two types of bias are calculated in the assessment of trueness: a proportional bias and a constant bias . we applied nested design for calculating proportional bias and youden method to calculate the constant bias. the results wc obtained for proportional bias are calculated from spiked samples. in this case , the concentration found is plotted against the concentration added and the slop of standard addition ofcurve is an estimate of the method recovery. estimated method of average recovery in human hair is: (1.0 i9±0.026), (0.918±o.014) and (1.0597±0.017) for cd, and ni, respe ctively .