A novel ETA-AAS background reduction method for determination of lead and cadmium in urine

Urinary lead and cadmium level were determined in double diluted urine samples using two modifiers: 1% HNO3 (own modification) and 1.6% NH4H2PO4 that is generally used for matrix modification. The background signal is reduced in the samples diluted with 1% HNO3 because of the modifying effect of nitric acid. Lower variation coefficients were obtained in a run of 10 determinations of each of the samples processed by our method which is an advantageous feature compared with the method using 1.6% NH4H2PO4 as a modifier. Recovery is between 95 and 105% for both methods. The analytical performance, flexible pre-instrumental preparation and minimized risk of sample contamination make the use of 1% HNO3 modifier a reliable method in the routine practice of determination of the urinary Pb and Cd level.