3.2. Retention, pyrolysis and atomization temperatures
The graphite furnace (GF) temperature program was optimized concerning the retention, pyrolysis and atomization temperatures, in the presence of a permanent modifier. The pyrolysis and atomization curves are shown in Fig. 4. In case of chemical vapor generation followed by vapor trapping in a graphite tube coated with a permanent modifier, a pyrolysis step is usually not needed. Initial investigations were made without this step, but strong drift in the signal was verified, most probably because of other vapors resulting from the reaction of the gasoline with the reductant, which were retained and released together with the analyte at the moment of the measurement. The inclusion of a pyrolysis step in the temperature program overcame this problem. The retention temperature was 100 °C, which was the lowest possible temperature to be inserted in the program.