Evaporation of Al, Cr, Ni and V in the classical uncontrolled DC arc spectrography and in the computer-controlled DC arc optical emission spectrometry was compared in the determination of the environmentally important elements. The experiments were carried out with a grating spectrograph PGS-2 and simultaneous multichannel LECO 750 spectrometer which was connected to the evaporation cell and adjusted to the Marinković plasma source. Standardized evaporation curves were obtained and the half-time and total evaporation time values were calculated. The basic statistical evaluation was also made.