Optimal Experimental Conditions Research Articles

Two‐Dimensional Copper‐Based Metal‐Organic Framework for Efficient Removal of Methylene Blue from Wastewater

Metal‐organic frameworks (MOFs) can effectively remove methylene blue (MB) from wastewater due to their abundant adsorption sites and multi‐level pores. In this paper, a copper‐based MOF: {[Cu·(L)·(H2O)]·(DMF)}n (1) (H2L = 2‐hydroxyterephthalic acid; DMF = N,N‐dimethylformamide), was synthesized by hydrothermal synthesis method. X‐ray single crystal diffraction showed that a two‐dimensional structure was formed by the carboxyl group of L2‐ in 1 took μ2‐η1：η1 bridged two adjacent Cu(II). In this two‐dimensional structure, the coordinated water molecules and hydroxyl group on L2‐ were distributed on the surface of 1. Thus, it had abundant adsorption sites. The transmission electron microscopy (TEM) of copper‐based MOF nano adsorbent showed that the particle diameter of the nano adsorbent prepared by a cell fragmentation apparatus was about 50 nm. The performance of the copper‐based MOF nano adsorbent in adsorbing MB indicated that the optimal adsorbent dosage was 0.20 g/L and the solution pH was 6. Under the optimal experimental conditions, its maximum adsorption capacity for MB was 143.3 mg/g, which was superior to most MOFs adsorbents. The adsorption thermodynamic analysis showed that the copper‐based MOF nano adsorbent at 25 ‐ 45 ℃ was an exothermic (△H < 0) , and spontaneous (△G < 0) process.

Magnetic Rubber@Ni-Co layered double hydroxide derived from ZIF-67 template as nanostructured sorbent; application in determination of anticancer drugs in plasma samples

In this study, a magnetic three-dimensional nano-composite based on Rubber-Fe3O4@Ni-Co Layered double hydroxide derived from ZIF-67 template was synthesized by a hydrothermal method. The proposed nano-composite was used as a sorbent for the enrichment of trace amounts of anti-cancer drugs (dasatinib and erlotinib hydrochloride) from plasma samples followed by determination using high-performance liquid chromatographic analysis (HPLC-UV). The synthesized nano-sorbent was characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating-sample magnetometer, Brunauer-Emmett-Teller surface analysis, Barrett-Joyner-Halenda pore size analysis and energy dispersive X-ray spectroscopy. Under optimal experimental conditions, factors affecting on extraction efficiency such as pH, ionic strength, extraction temperature and time, desorption solvent and time, the limit of detection (LODs) and the limit of quantification (LOQs) were obtained as 0.6, 2 µg/L for both of dasatinib and erlotinib, respectively. Also, linear range of the method were 2–500 and 2–1000 µg/L for dasatinib and erlotinib, respectively. Relative standard deviations (RSD%) for the repeatability of extraction on sorbent to sorbent were obtained as 3.59, 1.97 %, and one sorbent reusability were investigated and relative standard deviation values were obtained 5.35, 3.30 % for dasatinib and erlotinib, respectively.

Mild and friendly preparation of a high-surface porous organic polymers and its application for sensitive detections of endocrine disrupting chemicals

For sample pretreatment technique, the preparation of a stable, practical material with excellent enrichment performance is the core, and especially the preparation of an environmentally friendly adsorbent is desired. The preparation of most materials involves the use of organic solvents, which puts a strain on the environment to a certain extent, and the choice of aqueous solution as the reaction environment for the diazo-coupling reaction has attracted great attention, as a friendly strategy. We prepared the environmentally friendly porous organic polymer (POP) 2,4,6-tris(2,4,6-trihydroxyphenyl)-1,3,5-triazine-4,4′-diaminobiphenyl (CTT-BD) by diazo-coupling reaction, and further fabricated as stable solid phase microextraction (SPME) fiber. It achieved efficient extraction of derivatized bisphenol endocrine disrupting chemicals (EDCs) from water samples with enrichment factors ranging from 1306 to 2781. Under the optimum experimental conditions, the developed method by combining the CTT-BD coated fiber with gas chromatography mass spectrometry (GC–MS), demonstrated a wide linearity (10–10000 ng/L), low limits of detection (2.0–3.0 ng/L) and good reproducibility (relative standard deviations 3.1–8.1 %). Finally, the proposed method has been successfully used for the determinations of EDCs from water samples, and satisfactory recoveries (85.6–118.0 %) were achieved.

Assessment of activated carbon/alginate for the concurrent removal efficiency of paracetamol and caffeine from wastewater in their binary solutions

The increasing amount of pharmaceutical chemicals in wastewater is a concern for both public health and the environment. This research investigates the effectiveness of a new composite material made of alginate-activated carbon in removing caffeine and paracetamol from wastewater simultaneously. The composite material, produced using a simple technique, demonstrates excellent removal rates and exceptional adsorption properties for both medicinal chemicals. The structural stability and integrity of the composite are confirmed through comprehensive characterization methods including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, energy dispersive X-ray (EDX), and BET surface area analysis. The study uses batch adsorption experiments to assess the impact of various factors, such as pH, initial concentration, and contact time, on the efficiency of caffeine and paracetamol removal. The highest values for the adsorption process were 89.63% for Paracetamol and 97.32% for Caffeine, achieved under optimal experimental conditions (pH 7, 0.1 g dose of adsorbent at elevated temperature). Additionally, Kinetic studies and thermodynamic parameters such as ΔS°, ΔGº, and ΔH° were calculated, indicating that the adsorption process was endothermic and spontaneous for paracetamol, and exothermic and non-spontaneous for caffeine. Seven non-linear equilibrium isotherm models were utilized to fit the experimental data for paracetamol and caffeine at pH 7 showing maximum adsorption capacities (qmax) of 606.80 and 725.05 mg/g for Paracetamol and Caffeine, respectively with a high regression coefficient (R2) of 0.99 using alginate-activated carbon as an adsorbent, The results demonstrate the potential of alginate-activated carbon as an effective adsorbent for the simultaneous removal of various pharmaceutical pollutants, highlighting the synergistic adsorption effects of the composite material. The study also examines the safety of the composite material, particularly in the context of potential medical applications. The study emphasizes the potential for sustainable and repeated use of the activated carbon/alginate composite, demonstrating that it maintains both its structural integrity and adsorption effectiveness after multiple cycles of use. This study evaluated the suitability of the suggested analytical method using BAGI, a metric with a unique formula. The BAGI is a complementary tool to GAPI, Complex GAPI, AGREE, AGREE prep, and ESA. A major focus is on the practical elements of white analytical chemistry centered around "blue”.

Experimental conditions for room temperature ferromagnetism in Fe-doped SnO2 via mechanochemical milling and thermal treatment

Identifying optimal experimental conditions, preferably through a simple and cost-effective method, for the fabrication of oxide-diluted magnetic semiconductors, such as Fe-doped SnO2, holds great significance in the quest for spintronic materials operating at room temperature (RT). While mechanochemical milling is a well-established technique meeting these requirements, its numerous milling variables necessitate careful consideration of restricted experimental conditions. In this study, we present some experimental mechanochemical milling conditions to prepare impurity-free iron-doped tin dioxide nanoparticles exhibiting RT ferromagnetic signal. To achieve this, we investigated the effects of milling time, the choice of the starting Sn reactant, and iron concentration on the purity of Sn1−xFexO2 (x = 0, 0.03, and 0.05) nanopowders obtained through mechanochemical milling followed by thermal treatment. Characterization through XRD, XANES, and EXAFS at the Fe K-edge, RT Raman spectroscopy, 119Sn and 57Fe Mössbauer spectroscopies, and magnetic measurements was conducted. Among the experimental techniques, micro-Raman spectroscopy proved the most effective in detecting the formation of hematite as an impurity phase. Our results indicate that extending the milling time to 12 h, as opposed to 3 h, employing anhydrous SnCl2, instead of SnCl2·2H2O and using the low iron concentration of x = 0.03, results in proper conditions for producing impurity-free samples with a robust RT ferromagnetic signal. The oxidation states for iron and tin ions were determined to be 3+ and 4+, respectively, with both occupying octahedral sites, suggesting iron’s replacement of tin. Our findings propose that both the bound magnetic polaron and RKKY models offer potential explanations for the origin of the ferromagnetic signal observed at room temperature in Sn0.97Fe0.03O2 sample milled for 12 h.

Synthesis, Characterization, and Optimization of Novel Furan-ring Fused Chalcones via Radical Cyclization of α,β-Unsaturated Ketones and Cyclic Ketone

Abstract: Novel Furan-ring Fused Chalcones (FFC) were synthesized using a radical cyclization reaction of α,β-unsaturated ketones with cyclic ketone as the model reaction to attain this goal. In this study, traditional and microwave-assisted methods for the efficient and cost-effective synthesis of furan-ring fused chalcones in mild reaction conditions are compared and optimized. The goal is to develop a reliable and adaptable synthetic technique that may be used to produce these useful chalcone derivatives quickly and effectively. The optimal experimental conditions for these reactions were carefully determined using two independent methodologies: conventional (Method A) and microwave (Method B). The results indicated that the proposed method B could be used effectively in the future to synthesize novel furans with short reaction times and acceptable yields (87-94 %), and products were purified by column chromatography and preparative thin layer chromatography (PTLC). All new compounds were characterized by 1H-NMR, 13C-NMR, LC-MS, and elemental analyses.

A fluorescent functionalized PET fabric with dual-response to aqueous copper and pH

A fluorescent functional PET fabric for effective aqueous copper detection was developed. Eu(TTA)3·2H2O complex was prepared by the solvothermal method and subsequently PET fluorescent nonwoven fabrics were prepared by coordinating the complexes with PET nonwoven fabrics grafted with acrylic acid.The chemical structure and microscopic morphology of the fluorescent nonwovens were analyzed, and the effects of different experimental conditions (grafting rate, reaction time, and fluorescent complex concentration) on the fluorescence properties of the materials were investigated. Under optimal experimental conditions, the fluorescent nonwoven fabric exhibited a fluorescence intensity of 2.1 × 105 a.u. and a quantum yield of 6.35%. Additionally, the fluorescence intensity of the fluorescent nonwoven fabric decreased with the increase of aqueous copper concentration, and the quenching effect could be described by the Stern-Volmer equation. Furthermore, adjusting the pH of the aqueous copper at a fixed concentration revealed a linear relationship between the fluorescence intensity and pH. These observations demonstrate a dual response of the fluorescent nonwoven fabric to both aqueous copper and pH, enabling its potential application in the detection of both analytes.

Electrochemical Sensor for the Detection and Accurate Early Diagnosis of Ovarian Cancer.

Ovarian cancer (OC) has the highest mortality rate among malignant tumors, primarily because it is difficult to diagnose early. Exosomes, a type of extracellular vesicle rich in parental information, have garnered significant attention in the field of cancer diagnosis and treatment. They play an important regulatory role in the occurrence, development, and metastasis of OC. Consequently, exosomes have emerged as noninvasive biomarkers for early cancer detection. Therefore, identifying cancer-derived exosomes may offer a novel biomarker for the early detection of OC. In this study, we developed a metal-organic frameworks assembled "double hook"-type aptamer electrochemical sensor, which enables accurate early diagnosis of OC. Under optimal experimental conditions, electrochemical impedance spectroscopy technology demonstrated a good linear relationship within the concentration range of 31-3.1 × 106 particles per microliter, with a detection limit as low as 12 particles per microliter. The universal exosome detection platform is constructed, and this platform can not only differentiate between high-grade serous ovarian cancer (HGSOC) patients and healthy individuals but also distinguish between HGSOC patients and nonhigh-grade serous OC (non-HGSOC). Consequently, it provides a novel strategy for the early diagnosis of OC and holds great significance in clinical differential diagnosis.

A green EC/ECL dual-mode biosensing platform for detection of Vibrio parahaemolyticus

Here, a green EC/ECL dual-mode biosensing platform was designed for sensitive and accurate detection of Vibrio parahaemolyticus (VP). When VP was present, Apt on Fe3O4@SiO2-cDNA/Apt was specifically bound to VP and detached to obtain Fe3O4@SiO2-cDNA. Subsequently, aDNA on Zn-TCPP@AgNPs-aDNA was hybridized with cDNA on Fe3O4@SiO2-cDNA to obtain magnetic conjugates, which were quickly collected by magnetic force and then one-step assembled onto a magnetic glassy carbon (MGCE) electrode for EC/ECL dual-mode measurement. Under the optimal experimental conditions, the detection linear range of VP was 10 ∼ 107 CFU/mL, and the detection limits (LOD) were as low as 7 CFU/mL (EC) and 3 CFU/mL (ECL), respectively, with good repeatability, storage stability and selectivity. In addition, Fe3O4@SiO2-cDNA/Apt and Zn-TCPP@AgNPs-aDNA could be regained by adding Apt into the magnetic conjugates recovered after EC/ECL test, thus the biosensing platform was regenerated with the signal still remaining up to 91.7% (EC) and 92.8% (ECL) after 10 cycles of recovery. With homogeneous recognition and good regeneration, this EC/ECL dual-mode sensing platform provides a green, simple and reliable pathway for the analysis of VP or other foodborne pathogens.

Laboratory study on the transformation of oil-water interface properties under direct current electric field

Interface tension is one of the important mechanisms that affect crude oil recovery and plays an important role in the development of tight oil reservoirs. Electrical-enhanced oil recovery can be used as a technology to reduce interfacial tension and improve crude oil recovery. In the previous research process of Electrical-enhanced oil recovery, the focus was more on the influence of electric field on wettability, and the understanding of the changes in interfacial tension under electric field action is not yet comprehensive. This article designs an orthogonal experiment to study the effect of electric field on oil-water properties. The degree of influence of three factors, namely sodium chloride solution concentration (C), direct current voltage (V), and voltage action time (t), on interfacial tension is studied. Gas chromatography, four component analysis, and Fourier transform infrared spectroscopy are combined to discuss the mechanism of the influence of changes in solution pH, crude oil components, and oil phase functional groups on interfacial tension. The results show that an external electric field can effectively reduce the interfacial tension between oil and water, and the maximum change in interfacial tension after the experiment can be reduced from 23.21 mN/m to 0.37 mN/m; Through range analysis, it can be concluded that the concentration of sodium chloride solution has the greatest impact on interfacial tension, followed by DC voltage and voltage action time. The optimal experimental conditions are 0.5 mol/L sodium chloride solution, 10 V DC voltage, and a voltage action time of 18 h, and the change in interfacial tension is related to the increase in pH value. The change in crude oil composition is also an important reason for the decrease in interfacial tension under external electric fields. Finally, Fourier transform infrared spectroscopy was used to determine that under the action of an electric field, the increase in pH of the sodium chloride solution resulted in the formation of carboxylate salts through chemical reactions between alkaline substances of solution and acidic substances of the oil, which were the key factors in reducing interfacial tension. This study helps to understand and explore the principles and mechanisms of Electrical-enhanced oil recovery in improving oil recovery, with the aim of contributing to the development and promotion of Electrical-enhanced oil recovery technology.

Optimization and production of dairy-cereal grain-based probiotic beverage powder and its probiotic survivability under simulated gastric and pancreatic conditions

The present study uses maize flour and skimmed milk powder to develop a probiotic dairy-cereal-based food powder by spray drying and using response surface methodology for optimization. The processing parameters and ingredients, including inlet spray drying temperature (140–170 ℃), maize flour (80–120 g), and skim milk powder (60–80 g), were optimized against probiotic survivability count, moisture, sensory score, bulk density, and wettability as responses using response surface methodology. The optimum experimental conditions obtained to manufacture acceptable-quality powder were an inlet temperature of 151 ℃, an amount of maize flour of 102.74 g, and skim milk powder at 69.88 g. The probiotic survivability (8.35 log CFU/g) was observed at more than the recommended level (6.0 log CFU/g) due to the probiotic strain's microencapsulation by skim milk and maize flour components. The optimized powder had good nutritional and functional values and was observed to have acceptable water activity, surface structure, and color values. The shelf life of the product on the basis of probiotic survival (minimum 6.0 log CFU/g) was found to be 49 days at 4 ℃. Gastric and pancreatic survival was also observed at more than 50% in refrigerated conditions for up to 56 days of storage.

Combination of a magnetic ionic liquid and magnetic particles for the determination of Pb(II) and Sn(IV) using electrothermal atomic absorption spectrometry

A procedure for the determination of traces of lead and tin by electrothermal atomic absorption spectrometry (ETAAS) after complexation with diethyl dithiophosphate and preconcentration by using a microextraction stage with a magnetic ionic liquid (MIL) supported by ferrite particles is presented. After complexation, the analytes are extracted into the ferrite-supported MIL, the solid particles acting as a carrier to facilitate the separation with a magnet. The analytes are released by treating with acetonitrile and the resulting liquid phase is sampled for the ETAAS measurement. The optimal experimental conditions such as pH, appropriate complexing agent, volumes and doses of all reagents used in the procedure are studied to achieve complete separation of both species. Enrichment factors of 195 and 165 and detection limits of 25 and 72 ng L−1 are obtained for Pb and Sn, respectively. The reliability of the procedure is checked by analyzing six certified reference materials and applied to water samples of different origin, the results being in addition confirmed by standard additions (recoveries 97 ± 7% in all cases).

An antifouling electrochemical aptasensor based on a Y-shaped peptide for tetracycline detection in milk

Nonspecific adsorption of non-target components (especially proteins) in food matrix on sensing surfaces deteriorates accuracy and sensitivity of electrochemical sensors, which is a key challenge for food safety sensing. Therefore, electrochemical sensors with antifouling capability of high-protein food matrices are highly desired. In this paper, an efficient and simple antifouling electrochemical aptasensor for tetracycline (TC) analysis was constructed based on a self-designed Y-shaped peptide [CPPPPEK-(RSERSERSE)2] consisting of cysteine as the anchoring segment, polyproline as the supporting segment, and -EK-(RSERSERSE)2 as antifouling branches. Hydrophilic and electrically neutral amino acid sequence and Y-shaped space structure of the peptide endow the sensing surface with good antifouling performance in protein solutions and diluted milk. Under optimized experiment conditions, the proposed aptasensor can detect TC with a wide linear range (0.01–100 ng mL−1) and a limit of detection of 5.3 pg mL−1 (S/N = 3). The spiked recovery experiments confirmed high accuracy of the aptasensor in diluted milk without other pretreatments (recoveries: 90.96%–95.86%). This strategy offers a valid way to reduce matrix interference, showing a promise to be extended to other sensing systems for different targets.

A green route for the synthesis of sponge-like Pr6O11 nanoparticles and their application for the development of chlorambucil sensor

Herein, to fabricate the sponge-like praseodymium oxide nanoparticles (SL- Pr6O11 NPs), a facile and quick sonochemical route is introduced utilizing an environmentally friendly capping agent (Vitis vinifera juice) for the first time. Investigation of the electrochemical behavior of chlorambucil (CHB) showed that the reaction at the surface of the electrode is a diffusion-controlled procedure and the value of the diffusion coefficient (D) was calculated to be 1.35 × 10-5 cm2/s. The suitable electrochemical performance of the Pr6O11 nanoparticles (NPs) enhanced the sensitivity of the sensor for the electrochemical determination of CHB. The sensor signal was linearly proportional to CHB concentration in the range of 8 nM to 220 μM with a detection limit of 1.88 nM under the optimum experimental conditions. Additionally, CHB tablets, human urine and serum samples were successfully used as real samples to detect CHB at SL-Pr6O11/SPE with good recoveries.

Thymine-Hg2+-Thymine strategy in MOF-based electrochemical aptamer sensor for PAEs detection

Phthalate acid esters (PAEs), known food contaminants, can lead to reproductive problems, respiratory diseases, childhood obesity, and neuropsychological disorders. This work aims to develop an electrochemical aptamer sensor for the detection of DAP and its analogs. To achieve specific recognition ability for PAEs, we have introduced the thymidine-Hg2+-thymidine strategy for the first time in an electrochemical aptamer sensor, incorporating metal–organic frameworks (MOFs) as the carrier for the aptamer. Additionally, nano signal amplification technology was applied by immobilizing MXene on the electrode to intensify the sensor’s current signal. In the presence of PAEs, these molecules specifically bound to the aptamers, resulting in competitive release of Hg2+ and aptamers connected to Hg2+, subsequently reducing current signaling. Under optimal experimental conditions, the designed sensor achieved a linear range from 1.65 × 10−5 mg/mL to 3 × 10−3 mg/mL and an extremely low detection limit of 8.94 × 10−6 mg/mL. Furthermore, it exhibited good reliability and practicality in detecting actual samples.

Hydrophobic deep eutectic solvent-based vortex-assisted dispersive liquid–liquid microextraction with UV–visible spectrophotometry for copper determination in waste printed circuit boards

ABSTRACT Nearly all electronic devices utilise Printed Circuit Boards (PCBs), which contribute significantly to the generation of electronic waste (e-waste). They are rich in metal content, with copper being present in higher percentages. In this work, a simple, efficient and environment-friendly pre-concentration technique was developed, using hydrophobic deep eutectic solvent as an extractant in vortex-assisted dispersive liquid–liquid microextraction. This pre-concentration technique is coupled with spectrophotometry for the determination of copper in PCBs. The complexing agent, sodium diethyl di-thiocarbamate (DDTC), and copper formed a complex in the 2–3 pH range. The Cu-DDTC complex was vortexed for 1 min at 2800 rpm to extract in hydrophobic DES. The sediment was analysed using a UV–Visible spectrophotometer at λ max 435 nm. The optimisation parameters, including pH, extraction solvent selection and its volume, concentration and volume of chelating agent, interference of forein ios, etc., have been assessed. Analytical figures of merit such as limit of detection (1.98 μg/L), limit of quantification (5.9 μg/L), relative standard deviation (3.4%) and enrichment factor (10) have been obtained under optimal experimental conditions. The method was validated by a certified copper solution and applied successfully to determine copper in waste PCBs of personal computers.

Highly sensitive rhodamine B dye-based electrochemical sensor for lactose detection

Lactose (LAC) is the main disaccharide sugar found in milk and dairy products, making it easily accessible as a food source. In addition to its importance for human and animal health, LAC concentrations serve as a biomarker of milk quality. In this study, we reported the detection of LAC using a highly sensitive electrochemical sensor based on rhodamine B (RhB) dye. The prepared RhB-based sensor exhibited excellent characteristics, including a straightforward manufacturing technique, cost-effectiveness, and exceptional sensitivity. We conducted a comparative analysis of the electrochemical response of the novel RhB-based sensor, evaluating its electrochemical performance across varying LAC concentrations and when different analyte materials (glucose, fructose, and maltose) were employed. The proposed analytical method was utilized to determine LAC using an electrochemical RhB-based sensor under optimal experimental conditions. As a result, it was experimentally observed that high sensor sensitivity of RhB based sensor against LAC was inversely proportional to the impedance value and directly proportional to conductance which corolated with the transport mechanism of RhB.

Simulation and Experimental Study of Circulatory Flash Evaporation System for High-Salt Wastewater Treatment

Treatment methods for high-salt wastewater mainly consist of physical methods, chemical methods and biological methods. However, there are some problems, such as slow treatment speed, high investment costs and low treatment efficiency. To address NaCl solutions, in this study, a circulatory flash system was designed based on gas–liquid equilibrium, mass conservation equation and energy conservation equation. A circulatory flash evaporation simulation and a static flash evaporation experiment were conducted on NaCl solutions under various operating conditions to investigate the effects of heating temperature, flash pressure and initial NaCl concentration on the circulatory flash evaporation system. The significance of each factor’s influence on the evaporation fraction and energy consumption was examined through static flash experiments. The simulation results demonstrated that increasing the heating temperature, decreasing the flash pressure and having a higher initial NaCl concentration could enhance the treatment capacity of high-salt wastewater. The flow rate of vapor outlets increased with higher heating temperature but decreased as the flash pressure rose. The experimental results demonstrated that flash evaporation pressure was the primary factor influencing both the evaporation fraction and the energy consumption per unit mass of vapor produced. It was observed that with an increase in heating temperature, the flash pressure decreased and there was a corresponding decrease in energy consumption per unit mass of vapor produced. The optimal experimental conditions were achieved at a heating temperature of 99 °C, a flash pressure of 15 kPa, and an initial NaCl concentration of 20%.

Thiol-based chemically modified carbon screen-printed electrode for simultaneous quantification of trace level Pb(II) and Cd(II).

Present work reports, the development of a novel electrochemical sensor based on a diazonium-coupling reaction and covalent attachment of the -NH2 group of cysteamine (Cyst) on screen-printed carbon electrode (SPCE), for simultaneous determination of Pb(II) and Cd(II). Initially, the in-situ generated 4-carboxyphenyl (4-CP) diazonium salt was electro-grafted to generate 4-CP/SPCE, followed by covalent bonding of terminal carboxylic group of 4-CP with -NH2 group of Cyst to give Cyst/4-CP/SPCE. The modified electrode showed an enhanced selectivity and sensitivity toward the quantification of Pb(II) and Cd(II) using square wave anodic stripping voltammetry (SWASV) without mutual interference. Under optimal experimental conditions, the newly designed sensor showed a wide linear range of 0.01µM to 0.7µM. The limit of detection (LOD) obtained was 0.882nM (0.09 ppb) and 0.65nM (0.134ppb) for Cd(II) and Pb(II), respectively. The modified SPCE exhibited good stability, selectivity, and reproducibility. Furthermore, the sensor was successfully applied for the determination of Pb(II) and Cd(II) ions in water samples which illustrated excellent recoveries in different spiked samples and the results were in line with the standard ICP-AES analysis.

Application of magnetic nanoparticles modified with poly(8-hydroxyquinoline) as a nanosorbent for magnetic dispersive micro-solid phase extraction of copper in vegetable, water, and soil samples

In this study, a novel nanosorbent, namely F3O4@SiO2 modified with poly(8-hydroxyquinoline) (Fe3O4@SiO2@PHQ), was synthesized and employed for magnetic dispersive micro-solid phase extraction of Cu(II) followed by flame atomic absorption spectrometry detection in water, vegetables, and soil samples. This nanosorbent was characterized using FT-IR, XRD, VSM, FE-SEM, and EDS. To attain the best extraction recovery, effective parameters were studied and optimized. Under the optimal experimental conditions, the extraction recovery was 92 %. The limits of detection and quantification were determined to be 0.64 ng mL−1 and 2.13 ng mL−1, respectively. The preconcentration factor was 92, and relative standard deviations for intra-day and inter-day measurements were 1.6 %, and 2.5 %, respectively. The linearity ranged from 2 to 200 ng mL−1 with an R2 value greater than 0.998 and relative recoveries in the range of 90–96 % in real sample analysis.