Determination of Low levels of Lead in Tap, River, Ground and Snow Waters using NH4H2PO4 and (NH4)2HPO4 modifiers with Tungsten-treated Pyrolytic Graphite Furnace Atomic Absorption Spectrometry

The W-treated pyrolytic graphite (PG) furnace made it possible to enhance the precision (RSD <2%), calculated limit of detection (LOD) and sensitivity of Pb by a 100 μL injection with 5 μL of modifier of 1w/v% NH4H2PO4 and 1w/v% (NH4)2HPO4. Using the phosphate modifier gave the LOD of 0.02 μg L-1 with a hollow cathode lamp as a radiation sauce. The modification effect on sulfate matrices, such as Na2SO4, K2SO4 and MgSO4 remaining a severe interference for a Pd modifier, was extended to be the upper limit to 50, 50 and 10 mg L-1 as cation concentration for each matrix, respectively. The recoveries of 1.00 μg L-1 of Pb added to tap, river and snow water samples were to be 104 ± 1 %, 105 ± 1 % and 102 ± 3 % with 1w/v% NH4H2PO4and to be 99±3 %, 99±2 % and 101±4 % with 1w/v% (NH4)2HPO4, respectively. The Pb concentration of Pb in a certified reference material of river water (MNIJ CRM 7202-a) was agreement with the certified value (1.01±0.02μg kg-1 )