Two new complexes of 5,11,17,23-tetra[(2-ethyl acetoethoxyphenyl)(azo )phenyl]calix[ 4 ]arene (TEAC) with Pb(lI) and Cr(IlI) were found in the pH range 9.5-11 in the mixture solvent methanol-water. The ratio of these complexes was 1:1 in the investigated condition. By using the Benese-Hildbrand method, the complex formation constants were calculated for TEAC Pb(lI) (K = 4.0x 10 exponent 4)
TEAC-Cr(III) (K = 1.2 x 10 exponent 5) and the molar extinction coefficients were 5x 10 exponent 4 and 1.42 x 10 exponent 4, respectively. Based on the optimum conditions of the complexes formation, the HPASM has been applied for simultaneous determination of Cr(IlI) and Pb(lI) with concentration ratio of Cr(IlI) to Pb(lI) varying from 2:1 to 1:20 (weight) in the mixed sample. The proposed method was successfully utilized to invest lead and chromium content in some plating waste water samples. The results for several analyzed samples were found to be in satisfactory agreement with those acquired by using the ICP-MS technique.