Determination of lead in the Parana River by solid phase spectrophotometry

the paper proposes a procedure for determination of lead in water samples by solid phase spectrophotometry (sps). it is based on the reaction of pb(ii) ion with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (5-br-padap) immobilized on an anion-exchange resin, that gives rise to a coloured complex, whose absorbance is measured directly at the solid phase. the method provides a detection limit of 2.4 μg l-1 and a sample throughput of 2 h-1. the relative standard deviation (r.s.d.) was 1.7% for a pb(ii) concentration of 10.0 μg l-1. the calibration graph obtained was linear with a correlation coefficient of 0.9995, in the range from the detection limit up to at least 100 μg l-1. this method was successfully applied to the determination of pb(ii) in natural superficial waters from the parana river in argentina.