Combination of flame atomic absorption spectrometry with ligandless-dispersive liquid- liquid microextraction for preconcentration and determination of trace amount of lead in water samples

Abstract

A new ligandless-dispersive liquid–liquid microextraction method has been developed for the separation and flame atomic absorption spectrometry determination of trace amount of lead(II) ion. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents. Factors influencing the extraction efficiency of lead, including the extraction and dispersive solvent type and volume, pH of sample solution, concentration of chloride and extraction time were studied. Under the optimal conditions, the calibration curve was linear in the range of 7.0–6000 ng mL⁻¹ of lead with R² = 0.9992 (n = 10) and detection limit based on three times the standard deviation of the blank (3S_b) was 0.5 ng mL⁻¹ in original solution. The relative standard deviation for eight replicate determinations of 1.0 mg mL^-1 lead was ±1.6%. The high efficiency of dispersive liquid-liquid microextraction to carry out the determination of trace amounts of lead in complex matrices was demonstrated. The proposed method has been applied for determination of trace amounts of lead in water samples and satisfactory results were obtained. The accuracy was checked by analyzing a certified reference material from the National Institute of Standard and Technology, Trace elements in water (NIST CRM 1643e).

KEY WORDS: Dispersive liquid–liquid microextraction, Lead determination, Preconcentration, Ligandless, Water analysis

Bull. Chem. Soc. Ethiop. 2013, 27(2), 161-168.

DOI: http://dx.doi.org/10.4314/bcse.v27i2.1