This standard includes principles and procedures for the determination of trace levels of: Ag, Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, TI, V and Zn in surface water, ground water, drinking water, waste water and sediments, using atomic absorption spectrometry with electrothermal atomization in a graphite furnace. The method is applicable to the determination of low concentrates of elements. The detection limit of the mehtod for each element depends on the sample matrix as well as of the instrument, the type of atomizer and the use of chemical modifiers. For water samples with a simple matrix (i.e. low concentration of deissolved solids and particles), the method detection limits will be close to instrument detection limits. The minimum acceptable detectin limit values for a 20--l sample volume are given in Table 1.