Solid phase extraction of trace amounts of palladium ions using multiwalled carbon nanotube modified by N,N’-bis(2-hydroxy-benzylidene)-2,2’(aminophenylthio) ethane prior to determination by flame atomic absorption spectrometry

Multiwalled carbon nanotubes modified with N,N’-bis(2-hydroxybenzylidene)-2,2’(aminophenylthio) ethane have been developed for the selective separation and/or preconcentration of trace amounts of Pd(II) in aqueous medium. Parameters including pH of aqueous solution, flow rates, the amount of ligand and the type of stripping solvents were optimized. It was found that the sorption is quantitative in the pH range (1.5-4), whereas quantitative desorption occurs instantaneously with 3.0 mL of 0.3 M Na2SO3. Linearity was maintained between 0.01 to 22 mg mL-1 for Pd in the final solution. The breakthrough volume was greater than 1800 mL with an enrichment factor of more than 600 and 6.0 mg L−1 detection limit (3s, n = 10). The effects of various ions interferences on the percent recovery of palladium ion were studied. The method was successfully applied to the determination of palladium ion in environmental samples. KEY WORDS: Multiwalled carbon nanotubes, Preconcentration, Palladium(II) determinationBull. Chem. Soc. Ethiop. 2012, 26(1), 19-26.DOI: http://dx.doi.org/10.4314/bcse.v26i1.

Preconcentration of Trace Amounts of Pb(II) Ions without Any Chelating Agent by Using Magnetic Iron Oxide Nanoparticles prior to ETAAS Determination

This work investigates the potential of magnetic Fe3O4 nanoparticles as an adsorbent for separation and preconcentration of trace amounts of lead from water samples prior to electrothermal atomic absorption spectrometry (ETAAS) determination. No chemical modifier is required in graphite furnace. Pb(II) ion was adsorbed on magnetic Fe3O4 nanoparticles in the pH range of 5.5–6.5, and then magnetic nanoparticles (MNPs) were easily separated from the aqueous solution by applying an external magnetic field; so, no filtration or centrifugation was necessary. After extraction and collection of MNPs, the analyte ions were eluted using HNO3 1.0 mol L−1. Several factors that may affect the preconcentration and extraction process, such as pH, type, and volume of eluent, amount of MNPs, sample volume, salting out effect, and interference ions were studied and optimized. Under the best experimental conditions, linearity was maintained between 0.005–0.5 ng mL−1. Detection limits for lead were 0.8 ng L−1 based on 3Sb. The relative standard deviation of seven replicate measurements of 0.05 ng mL−1 of Pb(II) ions was 3.8%. Finally, the method was successfully applied to extraction and determination of lead ions in the water and standard samples

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

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 (3Sb) 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)