SEPARATION AND PRECONCENTRATION OF ULTRATRACE LEAD IN BIOLOGICAL ORGANISMS AND ITS DETERMINATION BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

A biological organism (chitosan) was utilized to preconcentrate lead i ons from tap water. This preconcentration was achieved by mixing 0.8 m l of chitosan slurry with 10-50 ml of lead-containing solution and sub sequently separating by centrifugation. The chitosan paste was then di ssolved in 1 ml of 0.2%, nitric acid and analysed by graphite furnace atomic absorption spectrometry. The extraction efficiency can approach 100%, in the pH range 4-10. The amount of chitosan used was not criti cal. The effect of some impurities was also investigated. IF six sampl es were prepared simultaneously, the lime needed to preconcentrate eac h sample was less than 3 min. Two different modes of standard addition (the standard lead solutions being added before and after preconcentr ation) were used for analysis of tap water samples, and the results ob tained by the two modes were found to be quite consistent.