Result: The accuracy of method (through recovery) ranges from 94.80% - 104.94% (arsenic), from 95.47% - 104.08% (cadmium), from 96.06% - 103.11% (mercury); good repeatability (RSD = 1.27% - arsenic, 2.26% - cadmium, 2.46% - mercury), there was a strong linear correlation between the absorbance and the analyte concentration (arsenic in the concentration range from 1.0 - 12.0 ppb, the correlation coefficient R = 0.99997 and the linear regression equation y = 0.04691x - 0.00022, cadmium in the concentration range from 0.2 - 2.5ppb, the correlation coefficient R = 0.99999 and the linear regression equation y = 0.39935x + 0.01205, mercury in the concentration range from 5.0 - 50.0ppb, the correlation coefficient R = 0.99999 and the linear regression equation y = 0.00973x + 0.00027); limit of detection arsenic, cadmium and mercury were 0.043ppb, 0.005ppb and 0.178ppb, respectively; limit of quantitation arsenic, cadmium and mercury were 0.129ppp, 0.016ppb and 0.540ppb, respectively.