Nickel-manganese-cobalt tetragonal spinel ternary oxide nanocomposite as an effective adsorbent for dispersive solid phase micro-extraction of cadmium in food and water samples.

Nickel-manganese-cobalt tetragonal spinel ternary oxide nanocomposite (NMC-TSO) was synthesized. It was utilized as an efficient sorbent for the dispersive solid phase microextraction (D-SPµE) without vortexing of cadmium. The analysis of the cadmium was carried out by FAAS. The effective analytical parameters including pH (6) contact times (no vortexing), sample volume (70 mL), eluent volume (3 mL of 2 mol L-1 HCl), linear dynamic ranges (1.07-85.7 µg L-1), and re-useability (33) on the D-SPµE efficiency were investigated. The PF, RSD% and LOD of the D-SPµE for cadmium were 23.3, ≤ 2.8% and 0.49 µg L-1, respectively. The tolerable concentrations of Ca2+, Mg2+, K+ and Na+ on Cd(II) were 50,000 mg L-1, 50,000 mg L-1, 25,000 mg L-1 and 7500 mg L-1, respectively. The method was accurated by analysis of food and water certificate reference materials (NW-TMDA-54.6 Lake water, SPS-WW1 121 Batch wastewater, 1573a Tomato Leaves and TORT-3 Lobster Hepatopancreas) and - recovery experiments. The D-SPµE-FAAS method was applied for the cadmium determination in dam water, wastewater, river water, well water, sea water, tea, cacao, nut, bitter chocolate, rice, leek, cinnamon and parsley.

The Impact of Nano- and Micro-Silica on the Setting Time and Microhardness of Conventional Glass-Ionomer Cements.

The objective of this study was to investigate the effect of the incorporation of 2, 4 or 6 wt% of amorphous nano- or micro-silica (Aerosil® OX 50 or Aeroperl® 300 Pharma (Evonik Operations GmbH, Essen, Germany), respectively) on the net setting time and microhardness of Ketac™ Molar (3M ESPE, St. Paul, MN, USA) and Fuji IX GP® (GC Corporation, Tokyo, Japan) glass-ionomer cements (GICs) (viz. KM and FIX, respectively). Both silica particles were found to cause a non-linear, dose-dependent reduction in setting time that was within the clinically acceptable limits specified in the relevant international standard (ISO 9917-1:2007). The microhardness of KM was statistically unaffected by blending with 2 or 4 wt% nano-silica at all times, whereas 6 wt% addition decreased and increased the surface hardness at 1 and 21 days, respectively. The incorporation of 4 or 6 wt% nano-silica significantly improved the microhardness of FIX at 1, 14 and 21 days, with no change in this property noted for 2 wt% addition. Micro-silica also tended to enhance the microhardness of FIX, at all concentrations and times, to an extent that became statistically significant for all dosages at 21 days. Conversely, 4 and 6 wt% additions of micro-silica markedly decreased the initial 1-day microhardness of KM, and the 21-day sample blended at 4 wt% was the only specimen that demonstrated a significant increase in this property. Scanning electron microscopy indicated that the nano- and micro-silica particles were well distributed throughout the composite structures of both GICs with no evidence of aggregation or zoning. The specific mechanisms of the interaction of inorganic nanoparticles with the constituents of GICs require further understanding, and a lack of international standardization of the determination of microhardness is problematic in this respect.

Environmentally friendly nanoflower Al2O3@carbon spheres as adsorbent for dispersive solid-phase microextraction of copper and lead in food and water samples.

A fast and simple dispersive solid-phase microextraction method (d-SPµE) was described for the determination of copper and lead in food, water, and sediments using FAAS. Firstly, nanoflower Al2O3@carbon spheres composite (NF Al2O3@CSs) was synthesized and then characterized. The obtained NF Al2O3@CSs was used for the d-SPµE of copper and lead in aqueous solutions. The influence of important parameters like pH, contact time, eluent conditions, volume of sample, and competing ion effects on the d-SPµE efficiency of copper and lead was investigated. They were pH, 7; eluent, 2 mol L-1 HCl (2 mL); sample volume, 250 mL for copper and 150 mL for lead with recoveries ≥90%. The adsorption and elution of analytes on NF Al2O3@CSs were realized quickly without vortexing. The LODs of the d-SPµE for copper and lead were found to be 0.69 µg L-1 and 2.8 µg L-1, respectively, while its PF was 125 for copper and 75 for lead. The intra-day precision and inter-day repeatability (RSD%, n = 7) were 1.3% and 1.6% for Cu(II) and 2.3% and 3.2% for Pb(II), respectively. Finally, the accuracy of the d-SPµE was investigated by determination of the analytes in four certified reference materials (TMDA-53.3 Lake water, NW-TMDA-54.6 Lake water, NIST 1573a Tomato leaves, and NIST RM 8704 Buffalo River Sediment). The analyte recoveries together with analyses of dam water, river water, wastewater, sea water, sumac, tea, chocolate, and lentils were studied. The results indicate that recoveries ranged from 90 to 103% in water samples and 91 to 110% in food samples.

Dispersive solid-phase extraction with tannic acid functionalized graphene adsorbent for the preconcentration of trace beryllium from water and street dust samples.

In this study, tannic acid functionalized graphene as an adsorbent was synthesized and characterized by X-ray diffraction and scanning electron microscopy. It was used for the first time as an adsorbent for vortex-assisted dispersive solid phase extraction of trace Be(II) from water and street dust samples. The determination of beryllium was made by graphite furnace atomic absorption spectrometry. The effect of different parameters (pH, contact times, centrifuge rate and time, eluent type and volume, sample volume, and interfering ions) was investigated. The optimum pH was found to be 6. The adsorption and elution contact times were 3 min. The quantitative elution was carried out with 2 mL of 1.5 mol L-1 HCl. The preconcentration factor, detection limit and precision (as RSD%) of the method were found to be 125, 0.84 ng L-1, and 2.9%, respectively. The adsorbent showed good selectivity for Be(II) against interfering cations and anions and it was reusable up to 80 cycles. The accuracy of the developed method was confirmed by analyzing certified reference material (TMDA-70 Lake water) and by spiking tap water, wastewater, well water, and street dust samples.

Core-shell Fe3O4 polydopamine nanoparticles as sorbent for magnetic dispersive solid-phase extraction of copper from food samples.

In the present study, core-shell Fe3O4 polydopamine nanoparticles were synthesized and used for the first time as an adsorbent for the vortex assisted magnetic dispersive solid phase extraction of copper from food samples. After elution, copper in the solutions was determined by FAAS. The adsorbent was characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area, and zeta potential measurements. Various parameters affecting the magnetic dispersive solid-phase extraction were evaluated. The optimum pH and magnetic adsorbent amount were found to be 5 and 40 mg, respectively. Elution was made by 3 mL of 2 mol L-1 HNO3.The major advantage of the method is the fast equilibration during adsorption without the need for vortexing or shaking. The preconcentration factor and detection limit of the method were found to be 150 and 0.22 mg L-1, respectively. The precision (as RSD%) and adsorption capacity of the method were 3.7% and 28 mg g-1, respectively. The method was successfully verified by analyzing four certified reference materials (SPS-WW1 Batch 114 Wastewater, TMDA-53.3 Lake water, BCR-482 Lichen and 1573a Tomato Leaves) and by addition/recovery tests of copper standard solution in organic baby food, muesli, macaroni, honey, and milk samples.

Zirconium-based highly porous metal-organic framework (MOF-545) as an efficient adsorbent for vortex assisted-solid phase extraction of lead from cereal, beverage and water samples.

In this study, zirconium-based highly porous metal-organic framework, MOF-545, was synthesized and characterized. The surface area of MOF-545 was found to be 2192m2/g. This adsorbent was used for the first time as an adsorbent for the vortex assisted-solid phase extraction of Pb(II) from cereal, beverage and water samples. Lead in solutions was determined by FAAS. The optimal experimental conditions were as follows: the amount of MOF-545, 10mg; pH of sample, 7; adsorption and elution time, 15min; and elution solvent, 2mL of 1molL-1HCl. Under the optimal conditions of the method, the limit of detection, preconcentration factor and precision as RSD% were found to be 1.78µgL-1, 125 and 2.6%, respectively. The adsorption capacity of the adsorbent for lead was found to be 73mgg-1. The method was successfully verified by analyzing two certified reference materials (BCR-482 Lichen and SPS-WW1 Batch 114) and spiked chickpea, bean, wheat, lentil, cherry juice, mineral water, well water and wastewater samples.

Ionic liquid coated carbon nanospheres as a new adsorbent for fast solid phase extraction of trace copper and lead from sea water, wastewater, street dust and spice samples.

In this study a new adsorbent, ionic liquid (1,8-naphthalene monoimide bearing imidazolium salt) coated carbon nanospheres, was synthesized for the first time and it was used for the solid phase extraction of copper and lead from various samples prior to determination by flame atomic absorption spectrometry. The ionic liquid, carbon nanospheres and ionic liquid coated carbon nanospheres were characterized by using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, (1)H NMR and (13)C NMR, Brunauer, Emmett and Teller surface area and zeta potential measurements. Various parameters for method optimization such as pH, adsorption and elution contact times, eluent volume, type and concentration, centrifuge time, sample volume, adsorption capacity and possible interfering ion effects were tested. The optimum pH was 6. The preconcentration factor, detection limits, adsorption capacity and precision (as RSD%) of the method were found to be 300-fold, 0.30µgL(-1), 60mgg(-1) and 1.1% for copper and 300-fold, 1.76µgL(-1); 50.3mgg(-1) and 2.2%, for lead, respectively. The effect of contact time results showed that copper and lead were adsorbed and desorbed from the adsorbent without vortexing. The equilibrium between analyte and adsorbent is reached very quickly. The method was rather selective for matrix ions in high concentrations. The accuracy of the developed method was confirmed by analyzing certified reference materials (LGC6016 Estuarine Water, Reference Material 8704 Buffalo River Sediment, and BCR-482 Lichen) and by spiking sea water, wastewater, street dust and spice samples.

Nanosized spongelike Mn3O4 as an adsorbent for preconcentration by vortex assisted solid phase extraction of copper and lead in various food and herb samples.

In this paper, a nanosized spongelike Mn3O4 was synthesized and used for the first time as an effective adsorbent for vortex-assisted separation and preconcentration of lead and copper from various food samples. Copper and lead were determined by flame atomic absorption spectrometry. The characterization of the nanosized spongelike Mn3O4 was performed by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, Brunauer, Emmett and Teller surface area and zeta potential measurement. The contact times for both adsorption and elution were only 3min. Under the optimized conditions, detection limits for copper and lead were found to be 2.6µgL(-1) and 3.0µgL(-1), respectively. The relative standard deviations were found to be ⩽3.2%. The accuracy of the method was confirmed by analyzing the standard reference materials (BCR-482 Licken and SRM 1573a Tomato Leaves) and spiked real food and herb samples.

Spectrophotometric determination of basic fuchsin from various water samples after vortex assisted solid phase extraction using reduced graphene oxide as an adsorbent.

In this study, a fast and simple vortex assisted solid phase extraction method was developed for the separation/preconcentration of basic fuchsin in various water samples. The determination of basic fuchsin was carried out at a wavelength of 554 nm by spectrophotometry. Reduced graphene oxide which was used as a solid phase extractor was synthesized and characterized by X-ray diffraction, scanning electron microscopy and the Brunauer, Emmett and Teller. The optimum conditions are as follows: pH 2, contact times for adsorption and elution of 30 s and 90 s, respectively, 10 mg adsorbent, and eluent (ethanol) volume of 1 mL. The effects of some interfering ions and dyes were investigated. The method was linear in the concentration range of 50-250 µg L(-1). The adsorption capacity was 34.1 mg g(-1). The preconcentration factor, limit of detection and precision (RSD, %) of the method were found to be 400, 0.07 µg L(-1) and 1.2%, respectively. The described method was validated by analyzing basic fuchsin spiked certified reference material (SPS-WW1 Batch 114-Wastewater) and spiked real water samples.

Nano sponge Mn2O 3 as a new adsorbent for the preconcentration of Pd(II) and Rh(III) ions in sea water, wastewater, rock, street sediment and catalytic converter samples prior to FAAS determinations.

In this study, a nano sponge Mn2O3 adsorbent was synthesized and was used for the first time. Various parameters affecting the recovery values of Pd(II) and Rh(III) were examined. The tolerance limits (≥ 90 %) for both Pd(II) and Rh(III) ions were found to be 75,000 mg L(-1) Na(I), 75,000 mg L(-1) K(I), 50,000 mg L(-1) Mg(II) and 50,000 mg L(-1) Ca(II). A 30s contact time was enough for both adsorption and elution. A preconcentration factor of 100 was obtained by using 100mg of the nano sponge Mn2O3. The reusability of the adsorbent was 120 times. Adsorption capacities for Pd(II) and Rh(III) were found to be 42 and 6.2 mg g(-1), respectively. The detection limits were 1.0 µg L(-1) for Pd(II) and 0.37 µg L(-1) for Rh(III) and the relative standard deviations (RSD, %) were found to be ≤ 2.5%. The method was validated by analyzing the standard reference material, SRM 2556 (Used Auto Catalyst Pellets) and spiked real samples. The optimized method was applied for the preconcentration of Pd(II) and Rh(III) ions in water (sea water and wastewater), rock, street sediment and catalytic converter samples.

Ultralayered Co3O4 as a new adsorbent for preconcentration of Pb(II) from water, food, sediment and tobacco samples.

In this study, ultralayered Co3O4 adsorbent was synthesized and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface area of the solid material was found to be 75.5m(2)g(-1) by BET method. The ultralayered Co3O4 was used for the first time as an effective adsorbent for the preconcentration of the Pb(II) ions in various samples prior to flame atomic absorption detection. Analytical parameters affecting the solid phase extraction of Pb(II) such as pH, adsorption and elution contact time, eluent volume and concentration, sample volume and common matrix ions were investigated. The recovery values for Pb(II) were found to be ≥ 92% even in the presence of 75,000 mg L(-1) Na(I), 75,000 mg L(-1) K(I), and 75,000 mg L(-1) Ca(II) ions. 10s vortexing time was enough for both adsorption and elution contact times. The elution was easily made with 2 mL of 2.0 mol L(-1) HNO3. The reusability (170 cycles) and adsorption capacity (35.5 mg g(-1)) of ultralayered Co3O4 were excellent. The preconcentration factor of the method and detection limit were found to be 175 and 0.72 µg L(-1), respectively. The described method was validated with certified reference material (RM 8704 Buffalo River Sediment, BCR-482 Licken and SPS-WW1 Batch 111-Wastewater) and spiked real samples. It was also applied for the preconcentration of Pb(II) ions in various water (well water, mineral water, waste water and sea water), food (cauliflower and barley), street sediment and tobacco samples.

Structure of LaMo(2)O(5) Containing Both Isolated Mo(6)O(18) Clusters and Sheets of Fused Triangular Mo(3) Clusters.

The structure of the disordered lanthanum molybdate, LaMo(2)O(5), has been solved and refined using powder neutron diffraction data collected at 300 K. The average structure is described in P6(3)/mmc, a = 8.373(1) Å, c = 19.1510(1) Å, Z = 12. The compound contains two types of Mo-Mo bonded units: isolated octahedral Mo(6)O(18) clusters, and infinite molybdenum oxide sheets, formed from condensed triangular Mo(3)O(13) clusters joined together to give a total of four Mo-Mo bonds for each molybdenum. The Mo(6)O(18) clusters have 16 electrons available for metal-metal bonding and the Mo-Mo distances within the unit are 2.643(4) Å x 6 and 2.695(5) Å x 6. In the infinite sheets the molybdenum-molybdenum distances are 2.612(9) Å within one equilateral triangular cluster and 2.621(8) Å within another. Each of the molybdenum atoms in the two different Mo(3) clusters has two molybdenum neighbors from the other cluster at a distance of 2.882(6) Å. Disorder in this layered structure occurs because of interchange of layers of Mo sheets with layers of lanthanum ions. The Bragg scattering is accounted for by including layers occupied with a 50% probability by each of these structural elements and their associated oxygen atoms. A model showing how ordered subunits are stacked together to produce the average structure is presented. Extended X-ray absorption fine structure spectroscopy (EXAFS) at the Mo K-edge was used to give information on the local structure around molybdenum and to confirm that the final structural model gives a good description of Mo-O and Mo-Mo bonding.