GF-AAS Determination of Trace Amounts of Lead and Cadmium in Water After Separation and Enrichment by Co-precipitation

Trace amounts of Pb(Ⅱ) and Cd(Ⅱ) in water sample were co-precipitated by using the precipitate of Cu(Ⅱ) chelate with 2-mercaptobenzothiazole MBT-Cu(Ⅱ) in short as carrier from solution buffered at pH 9 with ammoniacal buffer.The precipitate was separated from the solution by centrifugation and dissolved in dilute HNO3,which was then used for GF-AAS determination of lead and cadmium under prescribed conditions.For coprecipitation of trace amounts of Pb(Ⅱ) and Cd(Ⅱ),e.g.,2.0 μg of Pb(Ⅱ) and 0.1 μg of Cd(Ⅱ),1 mg of Cu(Ⅱ) as MBT-Cu(Ⅱ) precipitate was necessary to be added as carrier,and values of recovery for both the elements attained were over 90%.Under the condition that the multiple of enrichment was taken as 100,the detection limits (3s/b) attained for Pb(Ⅱ) and Cd(Ⅱ) were 0.015 μg·L-1 and 0.003 μg·L-1 respectively.Values of RSD′s (n=7) found for the method,when applied to the analysis of 3 water samples,were 5.1% for Pb(Ⅱ) and 4.7% for Cd(Ⅱ).