Direct Sampling Graphite Furnace Atomic Absorption Spectrometry - A Suitable Tool for the Determination of Metallic Contaminants in Pitch

Considering the widespread use of pitch as a carbon source for manufacturing of carbon related materials, a method for the determination of Co, Cr, Cu, Mn and Ni in pitch by direct sampling graphite furnace atomic absorption spectrometry (DS-GF AAS) was proposed. The pyrolysis and atomization curves for reference solution and solid sample were evaluated. The influence of sample mass, the use of chemical modifier and the linear calibration range for each analyte were also evaluated. As advantages, the calibration with aqueous reference solutions was feasible for all the analytes and it was possible to use a relatively large sample mass, up to 3mg directly introduced into the graphite tube. The results obtained by DS-GF AAS were compared with those from analytes determination by inductively coupled plasma mass spectrometry after pitch digestion by microwave-induced combustion and no statistical differences (Student's t-test) were observed. The proposed method showed some advantages such as the minimum sample handling (only milling), the use of aqueous reference solutions for calibration and contrary to most work using GF AAS, Pd has been evaluated with no chemical modifier required, making the proposed method a suitable alternative for the quality control of pitch.