Determination of lead in groundwater samples of three aquifers of a coal mining area at various depths using advance extraction methodology

A simple and novel ultrasonically modified dual-cloud point extraction (Um-DCPE) method has been developed to preconcentrate a toxic heavy metal, lead (Pb2+), in aquifer water of different depths in the region of Thar coalfield, Pakistan, prior to analysed by flame atomic absorption spectrometry (FAAS). The Pb2+ in water samples have been complex with 8-hydroxyquinoline followed by the entrapping in the hydrophobic non-ionic surfactant (Triton X-114). The second step of Um-DCPE involved the addition of 0.5 to 2.0 mol L-1 of HCl/HNO3 (2 mL) and subjected to shaking and centrifugation, separate upper aqueous layers, and subjected for analysis. To check the performance of the proposed method a certified reference material (CRM) of water and spiked standard in a real sample were applied successively. Both LOD and LOQ achieved by the proposed method for Pb2+ were 0.023 and 1.70 mu g L-1, respectively. The optimised Um-DCPE method was applied effectively to selected aquifer water samples. The results obtained from the proposed method indicated that the aquifer water samples of different depths have 2 to 3 folds higher Pb2+ values than recommended values of the world health organisation.

Automated summary

A simple and novel ultrasonically modified dual-cloud point extraction method was developed to preconcentrate toxic heavy metal lead in aquifer water samples in Thar coalfield, Pakistan. The method showed high sensitivity and accuracy and revealed that the lead content in the water samples exceeded the recommended values by the World Health Organisation.