Wael I. Mortada

Determination of Cu2 +, Zn2 + and Pb2 + in biological and food samples by FAAS after preconcentration with hydroxyapatite nanorods originated from eggshell

Hydroxyapatite nanorods (HAPNRs) were prepared from recycled eggshell by using precipitation method. The structure of the HAPNRs was physicochemically and morphologically characterized by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The resulting HAPNRs were used for solid phase extractive preconcentration of Cu(2+), Zn(2+) and Pb(2+) prior to its determination by flame atomic absorption spectrometry. Experimental variables that influence the quantitative extraction of metal ions were optimized by both batch and column methods. The analytes were quantitatively sorbed on the matrix between pHs6 and 9. The maximum sorption capacity of the HAPNRs has been found to be 2.43, 2.37 and 2.53 mmol g(-1) for Cu(2+), Zn(2+) and Pb(2+), respectively, with the preconcentration factor of 250. The 3σ detection limit and 10σ quantification limit for Cu(2+), Zn(2+) and Pb(2+) were found to be 0.72, 0.55 and 5.12 μg L(-1) and 2.40, 1.83 and 17.06 μg L(-1), respectively. The calibration curves were linear up to 250 μg L(-1) for Cu(2+), 300 μg L(-1) for Zn(2+) and 400 μg L(-1) for Pb(2+). Accuracy of the proposed method was verified using certified reference materials (NCS ZC85006 Tomato, Seronorm Trace Elements Whole Blood L-1, Seronorm Trace Elements Whole Blood L-3 and Seronorm Trace Elements Urine). The present method was successfully applied to the analysis of these metal ions in sea water, biological and food samples.

A cloud point extraction procedure for gallium, indium and thallium determination in liquid crystal display and sediment samples

A simple, sensitive and rapid cloud point extraction (CPE) methodology has been developed for the selective separation and preconcentration of gallium, indium and thallium, after complexation with gallic acid in the presence of Triton X-114 as a non-ionic surfactant. The quantitative extraction of gallium, indium and thallium was performed at pH 2.5, with 0.04 mmol L−1 gallic acid, and 0.05% (w/v) Triton X-114 at 40 °C. The dilution of the surfactant-rich phase with acidified methanol was performed after phase separation, and the metal ions were determined using flame atomic absorption spectrometry. Under the optimized experimental conditions, the calibration curve is linear over the concentration range of 6–150 ng mL−1 for gallium, 2–150 ng mL−1 for indium, and 2–100 ng mL−1 for thallium. The limits of detection, based on three times the standard deviation of a blank signal by seven replicate measurements were 3.50, 1.25 and 0.92 ng mL−1. The relative standard deviations of this method were 1.55, 1.40 and 1.82% for gallium, indium and thallium, respectively (C = 50 ng mL−1, n = 7). The results showed that the developed method was not susceptible to interference effects, providing good recoveries. The developed method was successfully applied to gallium, indium and thallium determination in sediments and mobile phone liquid crystal display samples with satisfactory results.

Microwave assisted decoration of titanium oxide nanotubes with CuFe2O4 quantum dots for solid phase extraction of uranium

Titanium oxide nanotubes (TiOxNTs) were prepared using a hydrothermal method followed by ion exchange and phase transformation. The obtained TiOxNTs were decorated with CuFe2O4 quantum dots by assisted microwave procedures. The prepared nanomaterials were characterized by XRD, TEM, and IR spectroscopy. The decorated nanotubes (DTiOxNTs) were used as adsorbents for the removal of U(VI) from aqueous solutions prior to its determination by inductively coupled plasma-optical emission spectrometry. Experimental parameters including pH, contact time and amount of adsorbent were investigated by batch mode. Optimum sorption of U(VI) ions obtained at pH 6–8. The maximum adsorption capacity of DTiOxNTs towards U(VI) was found to be 366 mg g−1 which is better than that obtained by using TiOxNTs (277 mg g−1). The equilibrium adsorption isotherm of U(VI) was fitted with the Langmuir adsorption model. Moreover, a mini-column packed with DTiOxNTs was used for column-mode extraction and preconcentration of U(VI). The effects of layer thickness, sample volume, sample flow rate and eluent conditions were studied. Under the optimized column procedures, the preconcentration factor for U(VI) was 200. The 3σ detection limit and 10σ quantification limit were found to be 0.12 and 0.40 ng mL−1, respectively. The calibration curve was linear up to 1500 ng mL−1. The proposed method showed good performance in analyzing water samples of different sources and soil sample digests collected from agriculture land near an industrial area.

Cloud point extraction of some precious metals using Triton X-114 and a thioamide derivative with a salting-out effect

Abstract A cloud point extraction procedure is proposed for preconcentration of trace amounts of palladium (II), silver (I) and gold (III) in aqueous medium. The metal ions in the initial aqueous solution were extracted using the non-ionic surfactant, Triton X-114 after complex formation with 4-(p-chlorophenyl)-1-(pyridin-2-yl)thiosemicarbazide at pH 6.0 in the presence of 0.3 mol L−1 sodium sulfate as a salting-out agent at 25 °C. Dilution of the surfactant-rich phase with acidified methanol was performed after phase separation, and the metal ions were determined by electrothermal atomic absorption spectrometry. The main factors affecting extraction procedure, such as pH, concentration of the ligand, and amount of Triton X-114 were studied in detail. Under the optimum experimental conditions, the calibration graphs were linear upto 125, 50 and 100 μg L−1 and the enrichment factors were 52, 46 and 56 for palladium, silver and gold, respectively. The limits of detection, based on three times of standard deviation of blank signal by 10 replicate measurements divided by the slope of calibration curves were 0.12, 0.08 and 0.30 μg L−1 for palladium, silver and gold, respectively. The accuracy of the results was verified by analyzing spiked water samples. The proposed method has been applied for the determination of the metal ions in soil and rock samples with satisfactory results.

Mixed micelle-mediated extraction of alizarin red S complexes of Zr(IV) and Hf(IV) ions prior to their determination by inductively coupled plasma-optical emission spectrometry

A modified cloud-point extraction method using a mixed surfactant has been developed for the preconcentration of Zr(IV) and Hf(IV) prior to their determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). The method is based on the complexation of Zr(IV) or Hf(IV) with Alizarine Red S (ARS) at pH 2.5 in the presence of cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and non-ionic surfactant Triton X-114. Phase separation was accomplished at room temperature in the presence of 0.1 mol L−1 sodium sulphate. The surfactant-rich phase containing Zr(IV) or Hf(IV) was separated then diluted with methanol/concentrated nitric acid mixed solvent (5 : 1) before its introduction into ICP-OES for the determination. The optimal extraction and reaction conditions were evaluated and optimized. Under the optimized conditions, the calibration graphs were linear in the range of 0.5–1000 and 0.5–850 ng mL−1 with detection limits of 0.18 and 0.25 ng mL−1 for Zr(IV) and Hf(IV), respectively. The RSD values for five replicates of Zr(IV) and Hf(IV) at 50 ng mL−1 concentrations were 2.1 and 2.3%, respectively, and the enrichment factors for 100 mL samples were obtained as 120 and 105 for Zr(IV) and Hf(IV), respectively. The accuracy of the results was verified by analyzing the spiked water from different sources and synthetic mixtures. The proposed method has been applied for the determination of Zr(IV) and Hf(IV) in some real samples such as clay, rocks and silver alloy samples with satisfactory results.

Cloud point extraction for the determination of trace amounts of Pt(IV) by graphite furnace atomic absorption spectrometry

A cloud point extraction (CPE) system for the graphite furnace atomic absorption spectrometric (GFAAS) determination of Pt(IV) has been developed. The procedure is based on the complexation of Pt(IV) with 4-(p-chlorophenyl)-1-(pyridin-2-yl)thiosemicarbazide (HCPTS) in the presence of Triton X-114 as a non-ionic surfactant. The optimum conditions for the procedure were investigated with respect to several experimental parameters such as pH of the solution, Triton X-114 and HCPTS concentrations, incubation time and temperature, and centrifugation rate and time. Under the optimum experimental conditions, the calibration curve was linear up to 50 ng mL−1 with a detection limit of 0.25 ng mL−1 and the enrichment factor was 47. No considerable interference was observed due to the presence of coexisting anions and cations. The accuracy of the results was verified by analyzing the spiked water from different sources (tap, river, brackish, sea and industrial waste water). The proposed method has been applied for the determination of Pt(IV) in some real samples such as food and geological samples with satisfactory results.

Microwave assisted modification of cellulose by gallic acid and its application for removal of aluminium from real samples

Microwave assisted preparation of cellulose modified with gallic acid (MA-Cell-GA) was developed for high efficient adsorption of Al3+. The as-prepared modified cellulose has been characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta potential measurements. Energy dispersive X-ray (EDX) spectrum was utilized to proof the adsorption of Al3+. The effect of various experimental factors, as pH, amount of adsorbent, shaking time, initial metal ion concentration, temperature, concomitant ions and desorption conditions on the extraction efficiency was investigated and optimized in batch mode experiments. The adsorption capacity and the surface area of MA-Cell-GA were 59.6mgg-1 and 160m2g-1, respectively which were significantly higher than those of the sorbent obtained via traditional reflux procedure. The thermodynamic factors (ΔH° and ΔG°) values for adsorption of Al3+ on MW-Cell-GA confirmed the non-spontaneousity and exothermic character of the adsorption process. It was indicated that the prepared adsorbent can be regenerated easily using EDTA. The procedure was successfully applied for the preconcentration of Al3+ in water, rocks, blood and soil samples prior to the determination using inductively coupled plasma optical emission spectrometry (ICP-OES).

Solid Phase Extraction and Preconcentration of Trace Gallium, Indium, and Thallium Using New Modified Amino Silica

Amino silica gel functionalized with 2-hydroxy-5 -(2-hydroxybenzylideneamino)benzoic acid was synthesized, characterized and used as adsorbent for the removal of Ga3+, In3+ and Tl3+ from aqueous solution prior to their determination by flame atomic absorption spectrometry. Experimental parameters that affect the separation process were investigated in both batch and column modes. The maximum adsorption capacities of the sorbent are 61.7 mg g−1, 81.3 mg g−1 and 133.0 mg g−1 for Ga3+, In3+ and Tl3+, respectively. The preconcentration factor is 200 and the limits of detection of Ga3+, In3+ and Tl3+ are 4.10 μg L−1, 1.55 μg L−1 and 1.21 μg L−1, respectively. Interference by Al3+ can be masked by the addition of F−; and that of Fe3+ by its reduction to Fe2+ using 10% ascorbic acid. The method was successfully applied for the determination of these ions in water, sediments and liquid crystal display samples.

A new thiourea derivative [2-(3-ethylthioureido)benzoic acid] for cloud point extraction of some trace metals in water, biological and food samples

2-(3-Ethylthioureido)benzoic acid was prepared and characterized by electronic spectrum, elemental analysis, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectrum and mass spectrum. The produced ligand was applied for the preconcentrative of Fe3+, Co2+, Cu2+ and Zn2+ in aqueous samples by cloud point extraction methodology. Triton X-114 was used as extractant. Experimental parameters that may affect the extraction process were examined and optimized; such as pH, ligand and triton concentrations, type of diluting solvent, extraction temperature and ionic strength. The calibration curves were linear upto 500μgL-1 for Fe3+, Cu2+ and Zn2+ and upto 200μgL-1 for Co2+. The achieved detection limits were 1.5, 0.23, 0.71 and 0.35μgL-1 for Fe3+, Co2+, Cu2+ and Zn2+ respectively. The accuracy was established by analysis of certified reference materials (Seronorm whole blood L2 and ZCS ZC85006 Tomato). The proposed procedure was used for preconcentration of these metal ions in water, biological and food samples prior to their determination by flame atomic absorption spectrometry.

Impact of dialyzer membrane flux on metal clearance in hemodialysis patients

Deficiency of essential trace elements (such as Cu or Zn) and accumulation of potentially toxic trace elements (as Cd or Pb) are both known to have adverse effects in hemodialysis (HD) patients. Up to our knowledge, no studies about the permeability of low and high flux polysulfone membranes on metal ions during hemodialysis are available. Therefore, the aim of the present study was to address this issue. Forty one hemodialysis patients (19 were using high flux polysulfone membrane while the remaining were using low flux one) participated in the study. Blood levels of Cu, Zn, Cd and Pb were determined by graphite furnace atomic absorption spectrometry among HD patients, before and after dialysis session, as well as among matched 40 healthy persons. Blood concentrations of Cu and Zn in the whole hemodialysis group was significantly lower than those of the healthy control group, on the other hand the toxic metals (Cd and Pb) levels were observed to be significantly higher among HD patients compared to the normal persons. Among the hemodialysis group, there were no significant differences between the low and high flux dialyzer groups in terms of pre-dialysis blood levels of Cu, Zn, Cd and Pb. In addition, significantly decreased levels of all metal ions were observed after dialysis sessions using either low or high flux membranes. An exception was Pb which did not show any difference between pre-dialysis and post-dialysis values in the low flux groupIn conclusion Zn and Cu deficiencies should be considered in the treatment of these patients. High flux membranes are more efficient than low flux ones in removing excess Cd and Pb. Therefore, when high flux membranes are used, chelation therapy might not be required for Cd and Pb overload.