The mercury signal intensity for the gasoline diluted in ethanol decreased as the pyrolysis temperature increased, for the gasoline C1, but was stable up to 200 °C for the gasoline C2 and for the standard solution. For pyrolysis temperatures higher than 200 °C, the signal decreased steeply for all solutions. A pyrolysis temperature of 150 °C, which overcame the drift mentioned above, was adopted for further experiments.