Air-assisted solvent terminated dispersive liquid-liquid microextraction (AA-ST-DLLME) for the determination of lead in water and beverage samples by graphite furnace atomic absorption spectrometry

A preconcentration method based on a novel hybrid air-assisted solvent terminated dispersive liquid-liquid microextraction (AA-ST-DLLME) using a domestic fish-tank pump as a bubble generator was developed for the determination of Pb in water and beverage samples by GFAAS. The important parameters for the microextraction process (pH, concentration of complexing agent, type of extracting solvent, type of disperser, type of demulsifier, air-assisted time, and extraction time) were optimized. Under the optimized conditions, the enrichment factor (EF) of 58.9 was achieved, with the preconcentration factor (PF) of 60.0 and the extraction efficiency of 98.2%. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.025 ng/mL and 0.084 ng/mL, respectively. The relative standard deviation (RSD) was 1.02-3.19%. The proposed method was applied for the determination of trace level of Pb in water, fruit juice, and beverage samples. The spiked recovery at three different spiked concentrations were 82.0-117.3%. Results from the analysis of standard reference materials (SLRS-6) were not significantly different at the 95% of confidence level.