Abstract
	At present, the investigation of cationic components content in watter is of growing importance. The pollution of water environment by heavy metal cations is dangerous maninly because the natural selfpurification processes are insufficient as to their removing. Cumulation of heavy metals in the waters and worsening of their quality follows.
	In Slovakia, the quality of waters is governmentally standardized by normes. The present work is devoted to the analysing of heavy metal by method Atomic absortion spectrometry on tungsten atomizer WETA-88 in waters wery pure.
	The work deals with optimization parameters of the AAS-WETA-88 analytical method applied for determination of trace concentrations of the following polutants in the surface waters: Cd, Ag, Pb, Cr, Co and V.
	The advantageous characteristic mass values for many elements, not only for those forming hard decomposing carbides or oxides, can be achieved by atomization from tungsten surface. For determination of elements as Cd, Ag and Pb it is necessary to use such chemical modifiers witch act as thermal stabilizers during the samples thermal pretreatment. The modifiers for Cr, Co and V determination are important for improvement ot analytical characteristics as accuracy, precission, sensitivity and limit of detection. The influence of modifiers - NH4H2PO4 Pd (NO3)2, the mixture of Pd(NO3)2 + Mg(NO3)2 and NH4H2PO4 + Mg(NO3)2 for the determination of Cd,Ag and Pb was studied, while for the determination of Cr, Co and V the influence of NH4H2PO4, Pd(NO3)2 and La(NO3)2 ware studied. The optimal concentration of individual modifiers was determined and their buffering affects on certain types of chemical interferents (NaCl, CaCl2) were studied.
	Our investigations verified that this method can be used direct determination of Cd, Ag, Pb, Cr, Co and V in waters. It was found, that the concentration of the given heavy metals were in all cases uder the norm limit value.