44 research outputs found
Layered triple hydroxide (NiCoFe-LTH) with g-C3N4 hybrid nanocomposite as an adsorbent for Pb(II) extraction
No full textHybrid graphitic carbon nitride (g-C3N4) with layer triple hydroxide (LTH) nanocomposite synthesized using the hydrothermal procedure has been investigated as a novel adsorbent g-C3N4@NiCoFe-LTH in the dispersive solid phase microextraction (DSp-ME) for Pb(II) determination in the food and water samples. The nanocomposite was characterized using FTIR, SEM, SEM-EDX, and XRD techniques. Several analytical parameters were adjusted, including pH, adsorbent quantity, adsorption and elution time, sample and eluent volume, and elution solvent concentration, and found as 8.0, 7.5 mg, 60, and 30 s, 40 mL, 2 mL, and 0.5 mol/L, respectively. The method's accuracy was also evaluated using matrix effects. The results indicated the LOD as 0.163 μg/L, LOQ as 0.54 μg/L, and PF as 20. The percent relative standard deviation (%RSD) < 10 %, and the coefficient of determination (R2) was 0.999, demonstrating excellent precision and linearity. The method's effectiveness was also validated by analyzing certified reference materials (CRMs)
Synthesis of magnetic multi-walled carbon nanotubes with layered double hydroxide (M-MWCNTs@MnAl-LDH) nanocomposite as an adsorbent for lead extraction
No full textMnAl layered double hydroxide hybrid with magnetic-multiwalled carbon nanotubes was synthesized by a hydrothermal method and used for the extraction of Pb(II) (lead) from spices and water samples in the dispersive solid phase microextraction (dSPμE) technique using FAAS. The as-prepared adsorbent MMWCNTs@MnAl-LDH was characterized by XRD, FTIR, EDX, and SEM techniques. Various analytical parameters were optimized, including pH 8, adsorbent dosage of 5 mg, HNO3 eluent concentration of 1 mol L−1, eluent volume of 3 mL, eluent time of 60 s, and sample volume of 20 mL, for quantitative lead recoveries, with an LOD of 0.314 μg L−1, an LOQ of 1.048 μg L−1, and PF of 11.53. Under the optimized conditions, the linearity ranges from 0.5 to 500 μg L−1 (R2 = 0.9997). For the validation test of the established dSPμE procedure, Certified reference materials (CRMs) were used, yielding satisfactory recovery results ranging from 97.8 to 102.7 %. The method was applied to determine lead in turmeric, tap water, and industrial water samples
Introduction of a new ZnMgAl-LTH@GCN nanosorbent in dispersive solid phase microextraction (dSP-μ-E) procedure for Pb(II) extraction
No full textGraphitic carbon nitride (GCN) and layer triple hydroxide (LTH) were used in the development of a dispersive solid phase microextraction (dSP-mu -E) method for preconcentration of Pb(II). The new nanocomposite sorbent ZnMgAl-LTH@GCN was synthesized using a hydrothermal co-precipitation process, and characterized using various methods such as FT-IR, FE-SEM, XRD, and EDX. Analytical parameters were optimized; including pH, adsorbent amount, elute concentration/volume/time, and sample volume, which were found to be respectively, 8 pH, 5 mg, 1 mol/L, 1.5 mL, 60 s, and 35 mL. The matrix effects were also determined. The results found to be the preconcentration factor 23.3, limit of quantification (LOQ) 1.88 mu g/L and limit of detection (LOD) 0.560 mu g/ L, respectively. A validation test was conducted using CRMs to ensure appropriate recovery outcomes. The %RSD was found to be in the range of 6.12-7.72 %, remaining below the 10 % threshold. Pb(II) level was determined in tea, tap and industrial waste water samples using the new dSP-mu -E method
Activated carbon cloth with MnCoAl layer double hydroxide nanocomposite for the separation and preconcentration of Pb(II) and Ni(II) from food samples
No full textA novel dispersive solid phase microextraction (dSP-ME) technique using activated carbon cloth (ACC) and layered double hydroxide (LDH) has been developed for enriching and extracting Pb(II) and Ni(II). The ACC@MnCoAl-LDH nanosorbent, has proven with high surface area, superior extraction dynamics and efficiency, compared to traditional sorbents. Structural features of the new ACC@MnCoAl-LDH sorbent were also characterized. Analytical parameters such as pH, adsorbent quantity, sample volume, eluent volume, adsorption/desorption time, and concentration were optimized, using 7.5 mg of adsorbent. Limit of detection (LOD), limit of quantification (LOQ), and preconcentration factor (PF) were determined at 0.71 μgL -1, 2.35 μgL −1 and 25 for Pb(II) and 0.07 μgL -1, 0.22 μgL −1 and 30 for Ni(II). Validation tests also performed using certified reference materials (CRMs). The % RSD was calculated at 2.5–7.8 for Pb(II) and 3.5–8.2 for Ni(II). The method was applied to determine Pb(II) and Ni(II) levels in packet juices, noodles, and water samples
Supramolecular solvents in separation and preconcentration of organic and inorganic species
No full textDeep eutectic solvent based ultrasonic assisted liquid phase microextraction for the FAAS determination of cobalt
No full textA novel deep eutectic solvent based ultrasound-assisted liquid phase microextraction (DES-UALPME) has introduced for preconcentration of cobalt. Deep eutectic solvents (DESs) are studied as a green and eco-friendly solvents. In this method, 1-nitroso-2-naphthol was used as ligand. Cobalt concentration in DES rich phase was measured by a microsample injection system coupled with flame atomic absorption spectrometer (MS-FAAS). Under optimum conditions, LOD, LOQ preconcentration factor (PF) and % RSD were determined as 1.10 mu g L-1, 3.60 mu g L-1,15 and 7.1% respectively. The accuracy of the developed method was evaluated by the analysis of a pharmaceutical supplement and tea samples. Recoveries of certified reference materials and spiked samples were obtained in the range of 97-105%. Finally, the performance characteristics of the proposed method were compared with other liquid phase microextraction procedures. (C) 2016 Elsevier B.V. All rights reserved
Layer-by-Layer Modified Screen-Printed Carbon Electrode using Zirconium-Based Metal–Organic Framework, Quantum Dots, and Graphene for Enhanced Oxygen Evolution Reaction Performance
No full textElectrocatalysts for the oxygen evolution reaction (OER) must be effective, inexpensive, and long-lasting if electrochemical water splitting technologies are to advance. In this study, screen-printed electrodes containing ZIF-67—a zirconium-based metal–organic framework (Zr-MOF) composed of trimesic acid, carbon quantum dots (CQDs), and graphene nanoplatelets (GNPs)—were created using a layer-by-layer modification process. Increased number of active sites, increased surface area, and improved electron transport were demonstrated in structural and electrochemical testing of hybrid electrocatalyst systems. In comparison to reported electrodes, the ZIF/MOF/GNP-modified screen-printed carbon electrode (SPCE) performed significantly better at OER, with a reduced overpotential of 280 mV at 10 mA cm−2 and a Tafel slope of 40 mV dec−1. Electrochemical impedance spectroscopy (EIS) confirms a significant reduction in charge transfer resistance due to the improved interfacial conductivity. After 18 h of operation, the system displayed excellent performance with little drift, according to chromatopotentiometry testing. Because the MOF framework was made more conductive by the combined effects of conductive GNPs and CQDs, EIS revealed a reduction in charge transfer resistance. These findings suggest that a hybrid system consisting of ZIF, MOF, and GNP might be an effective electrocatalyst for cost-effective, scalable, and environmentally friendly water splitting applications. They additionally demonstrate that this SPCE-based layer modification method may be utilized for extensive, cost-effective water-splitting applications
Dispersive solid-phase microextraction of Cd(II) using CaFe layer double hydroxide with g-C₃N₄ nanocomposite from food and environmental samples
No full textA green and novel composite material integrating graphitic carbon nitride (g-C₃N₄) with layer double hydroxide CaFe-LDH has been developed for detecting Cd(II) ions in food and environmental samples using dispersive solid-phase microextraction (DSPME) method by flame atomic absorption spectroscopy. CaFe-LDH@g-C₃N₄ was synthesized via hydrothermal co-precipitation. The nanocomposite was characterized using various analytical techniques including FTIR, FESEM, XRD and EDX. Optimal conditions were set as pH 8, 15 mg adsorbent, 60 s adsorption time, 30 s desorption time, sample volume 25 mL and eluent volume 2 mL using 0.5 M HNO₃. The method shows low limit of detection (0.04 μg/L), limit of quantification (0.13 μg/L), and preconcentration and enrichment factor 12.5 and 12.32, respectively. It asserts high precision with a relative standard deviation under 10 % and an extraction efficiency of 101.4 %. The accuracy was validated using certified reference materials (CRMs), demonstrating the composite material effectiveness in quantifying Cd(II) concentrations across different matrices
Historical background: milestones in the field of development of analytical instrumentation
No full textSensitive and Fast Simultaneous Voltammetric Determination of Dopamine and Uric Acid Using Simple Screen-Printed Carbon Electrode Without Pretreatment and Modification
No full textA simple, commercially available, unmodified screen-printed carbon electrode (SPCE) was investigated for the simultaneous voltammetric determination of dopamine (D/A) and uric acid (U/A) in a medium of very low concentration of supporting electrolyte for the first time. The ordinary, simple SPCE from DropSens (DS-SPCE) was found to be able to separate the overlapping peaks of D/A and U/A with a wide peak potential separation of 300 mV in a medium of very low concentration (0.001 M) of NaH2PO4 as supporting electrolyte (buffer of low capacity) at pH 8.0. Medium of low concentration of electrolyte made it possible to expose the bare electrode surface for its high catalytic activity which resulted into a high peak current signals, particularly for D/A. The DS-SPCE showed excellent electrocatalytic performance than the other SPCE. The effect of electrolyte concentration and pH on the electrocatalytic behavior of electrode were thoroughly discussed. The DS-SPCE displayed a sensitive results in good linear ranges from 0.1–5 to 6–20 µM for D/A and 0.5–41.5 µM for U/A. The disposable electrode demonstrated better discrimination ability toward the detection of D/A and U/A over ascorbic acid and other potential interfering species. Moreover, the sensor presented sensitive and highly accurate results in human urine samples without preliminary treatment. The DS-SPCE sensor was found to be simple, efficient, fast, low cost, and greener than the other reported modified sensors, while providing better sensitivities to detect D/A and U/A simultaneously. Thus, the bare, unmodified DS-SPCE can be a convenient sensing device for the routine analysis of D/A and U/A, without requiring any complex pretreatment and modification steps of the electrode
