3.2. Graphite furnace atomic absorption spectrophotometry (GF-AAS)
Samples were determined for Pb and Cd by wet digestion in a closed digestion system (Teflon jar) using a mixture of concentrated nitric acid and perchloric acid (10:1, v/v) at 110 °C overnight until a clear solution was obtained. Pb and Cd from samples were extracted into the chloroform layer by complexion with ammonium-1-pyrrolidine dithiocarbamate (APDC), then diluted with nitric acid and minerals content was determined by GF-AAS (Varian, Graphite Components, Part No. 63-100012-00, Germany) using a standard addition method.