Argon with a purity of 99.996% (White Martins, São Paulo, Brazil) was used as the carrier gas for the vapor and as the purge and protective gas for the graphite atomizer. Pyrolytically coated tubes without platform (Analytik Jena, Part No. 07-8101225) were used throughout. Peak height, that is more sensitive than peak area because of the trapping on graphite tube coated with a permanent modifier, was used exclusively for the signal evaluation. The mercury hollow cathode lamp (IST-Horseheads, NY, no. WL22836) was operated at 7.0 mA, the wavelength was set to 253.7 nm and spectral band pass to 0.5 nm.