This paper reports viscosity measurements of oil/water (O/W) monodispersed emulsions of different droplet diameters obtained in a membrane emulsification system. Hydrophilic microporous glass membranes of different pore diameters were used to prepare O/W emulsions. The results showed that the droplet diameter of the emulsions varied with the average pore diameter of the membrane. The average droplet diameter was found to be about five times greater than the average membrane pore diameter. A correlation was found for the relationship between the average droplet diameter and the emulsion viscosity. As the dispersed droplet size became smaller, the total surface area of the droplets increased. Therefore, the emulsion viscosity and the relative viscosity increased. Few studies have reported the viscosity of O/W emulsions with droplet diameter of 5 micrometers or more and an oil phase concentration of 10 vol% or less. In the present study a correlation between the droplet diameter and the emulsion viscosity was statistically established.

Multifunctional polymeric microspheres were prepared using hyper-cross-linking chemistry combined with surface-initiated atom transfer radical polymerization. The synthesized microspheres exhibited good water dispersibility, a high surface area, and pH/thermo dual-responsiveness. Fluoroquinolones (FQs), which contains a hydrophilic piperazine ring and hydrophobic fluorine atoms, were used as target analytes to assess the performance of the microspheres as a sorbent for dispersive solid-phase extraction (d-SPE). The d-SPE experimental parameters, including extraction time, amount of microspheres, extraction temperature, and sample solution pH, as well as the desorption conditions, were systematically studied. Coupled with LCMS/MS, an analytical method for analysis of trace-level FQs in water samples was developed and validated. Under optimal conditions, linearity with correlation coefficients (r) of >0.99 was achieved in the concentration range of 0.02–10 μg L−1. The limits of detection and quantification for the selected FQs were 5.0–6.7 and 12–20 ng L−1, respectively. High recovery values (93.1%–97.2%), a high enrichment factor (˜180), and good precision (RSD < 8%, n = 6) were obtained for FQ determination in spiked purified water samples. It was proposed that hydrophilic–hydrophobic transition induced by stretching and shrinking of polymer chains under different pH and temperature conditions offered good control of the surface wettability and altered the extraction behavior. The developed method was validated and was successfully applied to the analysis of FQs in environmental water samples, meat and milk samples. These results demonstrated that the water-dispersible polymeric microspheres have good potential for use in separation and extraction techniques.

Water-based chitosans in the forms of oligochitosan (OligoCS) and nanowhisker chitosan (CSWK) are proposed as a novel food preservative based on a minced pork model study. The high surface area with a positive charge over the neutral pH range (pH 5–8) of OligoCS and CSWK lead to an inhibition against Gram-positive (Staphylococcusaureus, Listeriamonocytogenes, and Bacilluscereus) and Gram-negative microbes (Salmonellaenteritidis and Escherichiacoli O157:H7). In the minced pork model, OligoCS effectively performs a food preservative for shelf-life extension as clarified from the retardation of microbial growth, biogenic amine formation and lipid oxidation during the storage. OligoCS maintains almost all myosin heavy chain protein degradation as observed in the electrophoresis. The present work points out that water-based chitosan with its unique morphology not only significantly inhibits antimicrobial activity but also maintains the meat quality with an extension of shelf-life, and thus has the potential to be used as a food preservative.

Pharmaceutical and food pollutants have threatened global health. Pharmacotherapy has left a positive impression in the field of health and life of people and animals. However, the many unresolved problems brought along with residues of pharmaceuticals in the environmental and food. Consumption of the world's freshwater resources, toxic chemicals, air pollution, plastic waste directly affects water and soil resources. Pesticides have a wide role in pollutants. Therefore, the determination of pesticides is significant to eliminate their negative effects on living things. Nowadays, there are many analytical methods available. However, new analysis methods are still being researched due to certain limitations of traditional methods. Electrochemical sensors have drawn attention because of their superior properties, such as short analysis time, affordability, high sensitivity, and selectivity. The development of new analytical strategies for assessing risks from pharmaceutical to food pollutants in water and soil sources is important for the measurement of different pollutants. Moreover, the 2D-carbon nanomaterials used in the development of electrochemical sensors are widely utilized to enlarge the surface area, increase porosity, and make easy immobilization. Graphene (graphene derivations) and carbon nanotubes integrated nanosensors are widely used for the determination of pesticides. 2D-carbon nanomaterials can be tailored according to the purpose of the study. The characterization and synthesis methods of 2D-carbon nanomaterials are widely explained. Furthermore, enzyme nanobiosensors, especially Acetylcholinesterase (AChE), are widely used to determine pesticides. The three main topics are focused on in this review: 2D-carbon nanomaterials, pesticides that threaten life, and the application of 2D-carbon nanomaterials-based electrochemical sensors. The various developed 2D-carbon nanomaterials-based electrochemical sensors were applied in pharmaceutical forms, fruits, tap/lake water, beverages, and soils sources. This work aims to indicate the recently published paper related to pesticide analysis and highlight the importance of 2D-nanomaterials on sensors.

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 75.5m²g⁻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 75,000mgL⁻¹ Na(I), 75,000mgL⁻¹ K(I), and 75,000mgL⁻¹ Ca(II) ions. 10s vortexing time was enough for both adsorption and elution contact times. The elution was easily made with 2mL of 2.0molL⁻¹ HNO₃. The reusability (170 cycles) and adsorption capacity (35.5mgg⁻¹) of ultralayered Co₃O₄ were excellent. The preconcentration factor of the method and detection limit were found to be 175 and 0.72µgL⁻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.

An on-line flow injection pre-concentration-flame atomic absorption spectrometry method was developed to determine trace zinc in water (tap, dam, and well water), biological (hair and nail), and liver samples. As a solid phase extractant, a synthesized new chelating resin, poly(2-thiozylmethacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propane sulfonic acid) was used. The resin was characterized by Fourier transform infrared spectroscopy, elemental analysis, and surface area by nitrogen sorption. A pre-concentration factor of 40-fold for a sample volume of 12.6mL was obtained by using the time-based technique. The detection limit for the pre-concentration method was found to be 2.2μgL⁻¹. The precision (as RSD,%) for 10 replicate determinations at the 0.04μgmL⁻¹ Zn concentration was 1.2%. The calibration graph using the pre-concentration system for zinc was linear with a correlation coefficient of 0.998 in the concentration range from 0.005 to 0.05μgmL⁻¹. The applicability and accuracy of the developed method were estimated by the analysis spiked water, biological, liver samples (83–105%), and also certified reference material TMDA-70 (fortified lake water) and SPS-WW1 Batch 111-Wastewater. The results were in agreement with the certified values.

Fabrication of novel coatings continues to be an area of great interest and significance in the development and application of stir bar sorptive extraction (SBSE). In this work, a carboxyl-enriched microporous organic network (MON-2COOH) coated stir bar was designed and fabricated as a novel adsorbent for efficient extraction of four phenylurea herbicides (PUHs) before their determination by high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA). The MON-2COOH was represented as an effective adsorbent for PUHs due to its large surface area, rigid porous structure, aromatic pore walls and the desired hydrogen bonding sites of introduced carboxyl groups. Variables affecting the SBSE of target analytes were optimized in detail. Under the optimal extraction conditions, favorable correlation coefficients (R² > 0.996) in the linear range 0.10–250 μg L⁻¹, low limits of detection (LODs, S/N = 3) of 0.025–0.070 μg L⁻¹ and good enrichment factors (46–49) were obtained. Besides, the proposed SBSE-HPLC-PDA method was successfully applied to determine trace PUHs in food and environmental water samples with recoveries in the range of 80.0–104.8% and the precisions (relative standard deviations, RSDs) lower than 9.9% (n = 3). This work revealed the potential of MONs in SBSE of trace contaminants from environmental samples.

Herein, a novel Cu/CuFe₂O₄@iron-based metal-organic framework 88 A (Cu/CuFe₂O₄@MIL-88A(Fe)) was developed through a scalable hydrothermal strategy for the magnetic dispersive solid-phase extraction of chlorpyrifos and phosalone from water, fruit juice, and vegetable samples prior to corona discharge ion mobility spectrometry analysis. The resulting nanocomposite was characterized in detail, and thus the investigation indicated that the magnetic nanocomposite had good adsorption capacity, high surface area, dispersion, and superparamagnetic properties. In addition, the fabricated sorbent provided different interactions with the target analytes, (hydrogen bonding, hydrophobic contacts, and π-π stacking interactions) resulting in the improvement of extraction efficiency. The applied method based on Cu/CuFe₂O₄@ MIL-88A(Fe) was validated by investigating the affecting parameters, including the amount of magnetic nanocomposite (10.0 mg), sample pH (7.0), salt content (7.5 % w/v), extraction time (5 min), type of elution (150 μL of methanol), and desorption time (2 min). The linearity of the method was found to be in the range of 0.6–300.0 ng mL⁻¹ and 1.5–500.0 ng mL⁻¹, for chlorpyrifos and phosalone with the coefficient of determination of ≥0.9991. The limits of detections (LODs) of 0.2 and 0.5 ng mL⁻ ¹ were obtained for the determination of chlorpyrifos and phosalone, respectively. The relative standard deviation values (RSDs %) were calculated in the range of 4.4 %–6.1 % (intra-day, n = 5) and 6.3 %–8.0 % (inter-day, n = 3) for three days. Ultimately, the developed method was successfully applied for the extraction of the desired analytes from various spiked samples with acceptable recoveries (88.3–100.4 %).

Efficient extraction of polar sulfonamides antibiotics from aqueous samples and food is very challenging, because they are hydrophilic, their concentration is very low, and the matrix is complex. Covalent organic frameworks (COFs), a novel porous organic material, have attracted great attention. In this work, the spherical triphenylbenzene-dimethoxyterephthaldehyde-COFs (TPB-DMTP-COFs) were synthesized by a simple room temperature method, and due to their attractive properties, such as high outstanding acid-base stability, large specific surface area, low skeletal density, inherent porosity and high crystallinity, so TPB-DMTP-COFs as ideal solid phase extraction adsorbents showed excellent adsorption performance for trace polar sulfonamides in food and water. TPB-DMTP-COFs were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and so on. The important parameters were optimized to improve the extraction efficiency of TPB-DMTP-COFs toward sulfonamides. Analysis of sulfonamides was performed by liquid chromatography–tandem mass spectrometry. The developed method based on TPB-DMTP-COFs material achieved low limits of detection (0.5–1.0 ng L⁻¹), wide linearity (5–1000 ng L⁻¹), and good repeatability (2.5%–8.7%). The possible extraction mechanism was also discussed. Finally, the method was successfully applied to the enrichment and detection of sulfonamides in environmental water samples and food samples. The present study indicated that TPB-DMTP-COFs had splendid prospects in highly sensitive analysis of other pollutants in complex matrix.

Solid-phase extraction is one the most useful and efficient techniques for sample preparation, purification, cleanup, preconcentration, and determination of heavy metals at trace levels. In this paper, functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was applied for trace determination of copper, lead, cadmium, and nickel in water and seafood samples. The experimental conditions such as pH, sample and eluent flow rate, type, concentration and volume of the eluent, breakthrough volume, and effect of coexisting ions were optimized for efficient solid-phase extraction of trace heavy metals in different water and seafood samples. The content of solutions containing the mentioned heavy metals was determined by flame atomic absorption spectrometry (FAAS), and the limits of detection were 0.3, 0.4, 0.6, and 0.9 ng mL⁻¹ for cadmium, copper, nickel, and lead, respectively. Recoveries and precisions were >98.0 and <4 %, respectively. The adsorption capacity of the modified nanoporous silica was 178 mg g⁻¹ for cadmium, 110 mg g⁻¹ for copper, 98 mg g⁻¹ for nickel, and 210 mg g⁻¹ for lead, respectively. The functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN), and N₂ adsorption surface area measurement.