Abstract
This paper describes a new approach for the preconcentration of lead (Pb2+) by solventassisted dispersive solid phase extraction (SADSPE) prior to analyzing by flame atomic absorption spectrometry (FAAS). In this method, the dispersion of the sorbent was achieved by injecting a solution of the sorbent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy state resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. Pb ions reacted with 1-(2-pyridylazo)-2-naphthole (PAN) as chelating agent to form a hydrophobic complex. After extraction, phase separation was performed by centrifugation and as a result, the enriched analyte in this demented phase could be determined by FAAS. Some parameters that influenced solvent-assisted dispersive solid phase extraction and subsequent determination were evaluated in detail. Under optimized conditions (pH 9, PAN concentration: 1.0 × 10-3 mol L-1, sorbent: 0.1% m/v 1,4-dichlorobenzene, disperser solvent: 0.5 mL ethanol), a preconcentration factor of 50 could be obtained, and the limit of detection (LOD) for lead was 1.3 μg L-1. Relative standard deviation for ten replicate determinations of the standard solution containing 20 μg L-1 lead was 5.0%. The proposed method was successfully applied for the determination of lead in water samples with satisfactory results.
Highlights
The chemical pollution with heavy metals has been one of the serious problems for the sustainable environment
To obtain quantitative recoveries of lead using solventassisted dispersive solid phase extraction (SADSPE) method, the separation/preconcentration procedure was optimized for various parameters such as sorbent type and amount, type and volume of dispersive solvent, pH, chelating agent concentration, centrifuge conditions, and ionic strength
The effect of pH on the SADSPE of 20 μg L-1 of lead was studied in the range of 2-12
Summary
The chemical pollution with heavy metals has been one of the serious problems for the sustainable environment. Human activities have been considered to be responsible for environmental pollution by large amounts of toxic elements like lead. Lead and other toxic metals are released into the environment by several processes including waste and coal burning, industrial processes, volcanic emissions, metal mining, and smelting.[1,2] Exposure to these toxic elements imposes risks to human health, and to plants, animals and microorganisms.[3] According to the World Health Organization (WHO) the upper permissible level of lead in drinking water is 10.0 μg L−1.4 the determination of lead in sub-micron levels is still a challenging task. In spite of the increase in sophisticated analytical instrumentation aiming to improve the detection limits, many methods for metal determination at μg L-1 levels are still commonly performed using preconcentration procedures associated with techniques such as flame atomic
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