In this work, a method for simultaneous determination of four different elements, Co, Fe, Ni and K with high resolution continuum source graphite furnace atomic absorption spectrometry was developed. For this purpose less sensitive lines of four elements were selected (344.364 nm for Co, 344.388 nm for Fe, 344.626 nm for Ni and 344.641 nm for K). The pyrolysis and atomization temperatures were of 1000 and 2000 degrees C, respectively, and no chemical modifier was necessary. Calibration against aqueous standards lead to good agreement between certified or informed values and the determined values, at a statistical confidence level of 95%; recovery tests were performed for real samples, resulting in recoveries ranging from 90 to 110%. Limit of quantification for 0.050 mg L-1 Co, 0.173 mg L-1 Fe, 0.267 mg L-1 Ni and 0.629 mg L-1 K have been obtained, which are adequate for the purpose.