Magnetic dispersive micro-solid phase extraction merged with micro-sampling flame atomic absorption spectrometry using (Zn-Al LDH)-(PTh/DBSNa)-Fe3O4 nanosorbent for effective trace determination of nickel(II) and cadmium(II) in food samples

Synthesis of the modified SBA-15 mesoporous silica with TAN ligand to preconcentrate and determine trace amounts of Ni (II) ions in water and wastewater samples

The synthesis of modified mesoporous silica (SBA-15), a powerful and highly effective adsorbent, was provided for the preconcentration, extraction, separation, and determination of trace amounts of Ni (II) ions. In this method, SBA-15 modified with 1-(2-thiazolylazo)-2-naphthol (TAN) was used as a suitable absorbent. The absorption of Ni (II) ions was studied using the FAAS technique. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), energy-dispersive spectroscopy (EDS), Fourier-transform infrared (FT-IR) spectroscopy, and CHNS elemental analysis techniques were used to assess the characteristics of SBA-15 and TAN/SBA-15. Effective parameters (pH, amount of nanocomposite, extraction time, and type of recovery solvent) for extracting Ni (II) ions via TAN/SBA-15 were investigated. The merit figures of the method were obtained with appropriate results, such as detection limit, accuracy, enrichment factor, and preconcentration factor. The calibration curve was linear within the range of 5.0-50 ng mL-1 with a detection limit of 1.8 ng mL-1. High preconcentration, small relative standard deviations, and enrichment factors (approximately 100) were represented by the statistical analysis. The proposed method for measuring Ni (II) ions was used at trace levels in real samples, such as seawater, river water, well water, and wastewater from a textile factory, an electrical power station, an MDF factory, and a food industrial company, with satisfactory results.

Synthesis of ionically imprinted Poly(Alylthiourea) in the presence of 1-(2-Pyridylazo)-2-Napthol (PAN) for preconcentration in magnetic dispersive solid phase of nickel ions in water and food samples

In the present study, a magnetic ion-imprinted polymer based on n-allylthiourea in the presence of 1-(2-pyridylazo)-2-naphthol (MIIP-PAN) was synthesized, characterized, and applied in the preconcentration of nickel ions by dispersive magnetic solid phase extraction (DMSPE) with FAAS detection. For comparison, non-imprinted polymer (MNIP-PAN) and imprinted polymer without PAN were synthesized. The characterization of the polymers was performed by FT-IR, DRX, TEM, TGA, VSM, and BET. Selectivity studies were performed comparing the competitive adsorption of Ni2+ with other cations on MIIP-PAN and MNIP-PAN, achieving higher relative selectivity coefficients for MIIP-PAN than for MNIP-PAN and NIP. Under optimized conditions, the method provided a preconcentration factor of 76.70, detection limit of 0.25 µg/L and intra-day (2.06 - 2.33 %) and inter-day (1.82 - 4.90 %) precision. The developed method was applied to samples of water, teas, and chocolate powder, and its precision was evaluated through tests of recovery and analysis of certified materials.

Optimization of [P6,6,6,14+]3[GdCl63-] magnetic ionic liquid assisted dispersive liquid-liquid microextraction for selective and sensitive determination of cadmium in environmental water and food

A simple and green hydrophobic magnetic ionic-liquid assisted dispersive liquid-liquid microextraction (MIL-DLLME) was optimized for the determination of trace cadmium (Cd (II)) in environmental and food samples by flame atomic absorption spectrophotometer. To achieve selective and sensitive extraction of Cd (II), four MILs were prepared and tested. Extraction parameters of the MIL-DLLME including pH, type and volume of the MIL, type and volume of dispersive solvent, extraction cycle, ionic strength and sample volume were investigated in detail and optimized by Box-Behnken design. Under optimum conditions, matrix effect, recovery study, intra-day and inter-day precision were performed for the MIL-DLLM. The analytical characteristics such as limit of detection, limit of quantification and pre-concentration factor were 0.17, 0.56 and 125 ng mL-1, respectively. The validation of the MIL-DLLME was evaluated by analysis of reference materials. Moreover, the accuracy of the results in the analysis of real samples was evaluated by standard addition and quantitative recoveries (91 ± 5-101 ± 2%) were achieved. The results obtained in the analysis of both reference materials and real samples showed that the MIL-DLLME has a selective applicability for cadmium.

Magnetic layered double hydroxides for the sensitive dispersive solid phase microextraction of hippuric acid in urine samples prior to HPLC-UV analysis

The core- shell structural layered double hydroxide (Fe₃O₄-SiO₂-EN@Zn-Al-LDH) was successfully synthesized and applied as a solid sorbent in the magnetic dispersive micro solid-phase-extraction (M-DµSPE) method. It was combined with high-performance liquid chromatography for the trace analysis of hippuric acid (HA) from urine samples. The obtained magnetic layered double hydroxides (LDHs) were characterized by XRD, FT-IR, VSM, FE-SEM, and BET techniques. The characterization analysis indicated that Fe₃O₄- SiO₂- EN@ Zn-Al-LDH has a sufficient surface area and good saturation magnetism. The affecting variables on the extraction of HA by the proposed method were optimized. Excellent adsorption capacity (127.8 mg g^-1), wide linearity dynamic range (0.015-500 µg mL^-1), and satisfactory limits of detection and quantification (0.055 and 0.014 µg mL^-1, respectively) could be obtained under optimum conditions. The good repeatability and low relative standard deviation (7.2 %), low carry-over (2.7%), good matrix effect (93.6%), high reusability (up to 19 times), and an acceptable percent recovery value (97.2%) proved the selectivity and applicability of the proposed method for the extraction of the trace levels of HA in real urine samples.

Development of a Sensitive Method for Cadmium Determination in Fish Tissue and Drinking Water Samples by FAAS Using SQT In Situ Atom Trapping

A sensitive and robust trap method was developed for the determination of cadmium (Cd) by using a slotted quartz tube. Using this method at a sample suction rate of 7.4 mL/min for 4.0 min collection, a 1467-fold increase in sensitivity was obtained compared to the flame atomic absorption spectrometry method. Under the optimized conditions, a limit of detection of 0.075 ng mL^-1 was obtained for the trap method. The interference effects of hydride-forming elements, transition metals, and some anions on the Cd signal were investigated. The developed method was evaluated by analyzing "Sewage Sludge-industrial origin (BCR no: 146R)", "NIST SRM 1640a Trace elements in natural water", and "DOLT: 5 Dogfish Liver". There was a good agreement between the certified and found values at the 95% confidence level. This method was applied successfully for the determination of Cd in drinking water and some fish tissue samples (liver, muscle, and gill) obtained from Muğla province.

Covalent organic framework-LZU1@PEI@Fe3O4-based magnetic dispersive micro-solid phase extraction of tetracyclines from environmental water prior to HPLC analysis

In this work, COF-LZU1@PEI@Fe₃O₄ was synthesized by immobilization of COF-LZU1 onto the surface of polyethyleneimine-functionalized Fe₃O₄ nanoparticles (PEI@Fe₃O₄) and employed as an adsorbent for magnetic dispersive micro-solid phase extraction of tetracyclines (TCs). COF-LZU1@PEI@Fe₃O₄ was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and nitrogen adsorption-desorption isotherms analysis. The optimal extraction and desorption conditions were as follows: 15.00 mL sample solution (pH 7.0) extracted with 5.0 mg of adsorbent for 30 min at 30 °C, and then desorbed with 1.50 mL methanol/acetonitrile/0.02 mol L^-1 oxalic acid solution (v/v, 1 : 2 : 7). Good linearities were obtained between the peak area and TC concentration ranging from 5-500 μg L^-1 with correlation coefficients (R²) higher than 0.9992 and limits of detection lower than 0.51 μg L^-1. The relative standard deviations (RSDs) of intra-day and inter-day were less than 5.7% and 7.4%, respectively. The developed method was successfully applied to the determination of TCs in environmental water samples with recoveries in the range of 87.0-113.8% and RSDs less than 5.1%, suggesting great potential of COF-LZU1@PEI@Fe₃O₄ for efficient extraction and analysis of trace TCs in water samples.

A new analytical approach for preconcentration, separation and determination of Pb(II) and Cd(II) in real samples using a new adsorbent: Synthesis, characterization and application

A green and efficient analytical approach was reported for simultaneous preconcentration, and separation of Pb(II) and Cd(II) in water, vegetables, and barbecue samples by dispersive solid-phase microextraction prior to their determination using flame atomic absorption spectrometry. A new poly-3-hydroxy butyrate-polyvinyl triethyl ammonium chloride comb-type amphiphilic cationic block copolymer (PHBvbNCl) was synthesized and characterized. Main variables such as pH, sorbent amount, adsorption time, eluent type, desorption time, and sample volume were optimized. Detection limits and working ranges for Pb(II) and Cd(II) were 0.03 μg L^-1, 0.15 μg L^-1, 0.1-250 μg L^-1 and 0.5-375 μg L^-1, respectively. Enhancement factor for Pb (II) and Cd (II) were 114 and 98. The adsorption capacity of PHBvbNCl for Pb(II) and Cd(II) was 175.2 mg g^-1 and 152.9 mg g^-1. After the accuracy of the method was confirmed by the analysis of certified reference materials, it was successfully applied to real samples. Finally, the analytical performance of the present method was compared with other methods.