Solid-phase Extraction Research Articles

Sensitive Detection of Sibutramine and Fluoxetine Adulteration in Herbal Slimming Products by Means of Using Magnetic Solid Phase Extraction Combined with HPLC–DAD

Sensitive Detection of Sibutramine and Fluoxetine Adulteration in Herbal Slimming Products by Means of Using Magnetic Solid Phase Extraction Combined with HPLC–DAD

A Cu/β-cyclodextrin/reduced graphene oxide nanocomposite for efficient and multi-aflatoxin detection in rice, ginger and bean samples.

Aflatoxins (AFs) are some of the most important mycotoxins or fungal toxins that cause contamination of food products and are considered a threat to human and animal health. An efficient Cu/β-cyclodextrin/reduced graphene oxide nanocomposite (Cu/β-CD/rGO) has been prepared and applied as a new solid-phase extraction adsorbent for the separation and preconcentration of four AFs (B1, B2, G1, and G2) using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The successful synthesis of the prepared nanocomposite was confirmed using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The impacts of pH, amount of adsorbent, sample volume, desorption solvent volume, and salt concentration on the recovery of AFs were precisely investigated and optimized by central composite design (CCD). Under the optimal conditions, the introduced method demonstrated good linearity in the range of 0.4-5.4, 0.08-1.08, 0.4-5.4, and 0.08-1.08 ng g-1 for AFs B1, B2, G1 and G2, respectively. The limits of detection and quantification for the four AFs were obtained in the range of 0.06-0.53 and 0.20-1.62 ng g-1, respectively. The accuracy of the method was evaluated using recovery measurements in spiked real samples such as rice, bean, and ginger samples, and satisfactory recoveries were obtained in the range of 83.5-109.0% with good precision (RSDs between 2.4 and 8.6%). The results of this research revealed that our developed method is sensitive, highly effective, and convenient to perform for the trace analysis of AFs in different real samples.

Environmentally Benign Cellulose Acetate Hydrogel Beads for Solid Phase Extraction of Chlorpyrifos Pesticide from Water

Environmentally Benign Cellulose Acetate Hydrogel Beads for Solid Phase Extraction of Chlorpyrifos Pesticide from Water

Narrow-Bore Tube Magnetic Solid-Phase Extraction Method Utilizing Ionic Liquid-Modified Magnetic Nanoparticles for the Preconcentration and Determination of Catechin in Grape Juice

Narrow-Bore Tube Magnetic Solid-Phase Extraction Method Utilizing Ionic Liquid-Modified Magnetic Nanoparticles for the Preconcentration and Determination of Catechin in Grape Juice

Automated three-step solid-phase extraction of toxicologically relevant psychotropic compounds and metabolites from plasma followed by LC-MS/MS analysis

This study describes a method for the quantification of multiple toxicologically relevant compounds in plasma samples from suicide attempt patients using an automated three-step solid-phase extraction (SPE) with hydrophilic-lipophilic balance (HLB®) sorbent, with subsequent analysis by liquid chromatography-tandem mass spectrometry (LC/MS-MS). This novel approach simplifies the standard five-step SPE process by eliminating the conditioning and equilibration steps. Target analytes included amitriptyline, amphetamine, benzoylecgonine, carbamazepine, cocaethylene, cocaine, codeine, diazepam, fluoxetine, 3,4-methylenedioxymethamphetamine (MDMA), N-methyldiethanolamine (MDEA), methylenedioxyamphetamine (MDA), methamphetamine, morphine, nortriptyline, paroxetine, sertraline, and venlafaxine. Plasma samples (100 µL) were diluted with 4 % phosphoric acid in water, mixed with deuterated internal standards, and subjected to automated SPE using an ASPEC® automation. Analysis was performed using an octadecyl column (1.8 µm, 150 × 2.1 mm) with a 15-minute chromatographic run. The automated SPE took 24 min per sample. Intra-assay precision was 1.6–10.1 %, inter-assay precision was 1.5–5.8 %, and accuracy was 94.4 %–106.6 %. Extraction yields varied from 14.6 % to 78.7 %, with matrix effects ranging from −15.9 % to 13.3 %. The validated method was applied to samples from 50 suicide attempt patients, of which 28 contained quantifiable amounts of the target substances. This study describes the first application of an automated three-step SPE procedure for the extraction of multiple relevant analytes in emergency toxicology

Molecular insight into algae-derived dissolved organic matters via Fourier-transform ion cyclotron resonance mass spectrometry: Effects of pretreatment methods and electrospray ionization modes

The release of algae-derived dissolved organic matter (ADOM) significantly increased in serious eutrophication waters, posing great threats to drinking water safety. Thus, the molecular composition decipherment is urgently in need. However, due to unsatisfactory pretreatment and ionization effects, the application of Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) on ADOM was limited. Therefore, the effects of pretreatment methods (cartridge type and loading) during solid-phase extraction (SPE) and electrospray ionization (ESI) modes with FT-ICR-MS on the molecular composition of ADOM were evaluated. The results showed compared with silica-based octadecyl (C18) cartridge, styrene-divinylbenzene polymer (PPL) cartridge exhibited higher recovery efficiency and retained more saturated and oxygenated compounds, such as carbohydrate-like and tannin-like. Furthermore, the recovery efficiency decreased with increasing loading, and hydrophilic and high-oxygenated carbohydrate-like and tannin-like were continuously replaced by hydrophobic and low-oxygenated aliphatic and aromatic compounds. Moreover, compared to negative ESI mode, the addition of positive ESI mode increased the molecular chemodiversity, especially more lipid-like and protein-like compounds. Thus, we proposed < 1:500 DOC/PPL mass ratio during SPE and dual ESI modes coupled with FT-ICR-MS could identify ADOM molecules more comprehensively. This work contributes to more comprehensive understanding of the molecular composition of ADOM and provides more references for pretreatment and characterization strategies of severely eutrophic waters.

Endocrine-disrupting compounds in urban rivers of the southern border of Mexico: Occurrence and ecological risk assessment

The occurrence of seven endocrine-disrupting compounds (EDCs) in four urban rivers on the southern border of Mexico was studied in this work. The selected EDCs were 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), bisphenol A (BPA), bisphenol F (BPF), 4-nonylphenol (4NP) and 4-tert-octylphenol (4TOP). Water samples from the Coatan, Texcuyuapan, Cahoacan, and Coatancito rivers were collected at three different sites on each river and processed by solid phase extraction (SPE). The samples were analyzed by gas chromatography triple quadrupole tandem mass spectrometry (GC-MS/MS) and compounds of interest were identified by dynamic mass reaction monitoring mode (dMRM). Among the target EDCs, E2, BPA, and 4NP were detected in all water samples, with BPA being the most abundant ranging from 4.22 up to 127.96 ng/L. Correlation tests showed significant positive associations between estrogens and BPA, as well as the correlation between alkylphenols and BPA, suggesting common origin emission sources, which were identified as discharges of untreated municipal wastewater. Finally, the estimation of RQ and EEQ values indicated that the presence of E2, E3, EE2, and BPA in all sampled points represents a high risk for aquatic life in these sites, mainly for Texcuyuapan River, where the aquatic organisms may be susceptible to endocrine disruption by chronic exposure to detected compounds.

Occurrence, bioaccumulation, and partitioning of phthalate acid esters in the third largest freshwater lake (Lake Taihu) in China

Phthalate acid esters (PAEs) are a category of plasticizers that are ubiquitous in freshwater environments attributable to extensive utilization. We collected water, suspended particulate matter (SPM), surface sediments, phytoplankton, and zooplankton from 23 sampling sites to investigate and complement the occurrence, bioaccumulation, and partitioning of five PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), and di (2-ethylhexyl) phthalate (DEHP) in the third largest freshwater lake (Lake Taihu) of China. PAEs were extracted using Soxhlet extraction and solid phase extraction, and determined by gas chromatography-mass spectrometry. The average concentrations of the five PAEs in the water column, SPM, sediments, phytoplankton, and zooplankton of Lake Taihu were 1.93±1.57μgL-1, 765±766μgg-1, 1.68±1.47μgg-1, 1358±1877μgg-1, and 72.7±134μgg-1, respectively. DBP and DEHP were the dominant PAE congeners in the five environment compartments. The logarithmic concentrations of DBP, BBP, and DEHP in the SPM were negatively correlated with the logarithmic content of the SPM. Biodilution significantly impacted the occurrence of PAEs in the plankton. Bioaccumulation of PAEs was found in the plankton with log BCF (bioconcentration factor) in the phytoplankton ranging from 1.78±0.86 to 4.13±1.23 and log BAF (bioaccumulation factor) in the zooplankton varying from -0.10±0.26 to 3.04±0.64. Biomagnification of the PAEs from phytoplankton to zooplankton was not observed. DMP, DEP, and BBP migrated from sediments to water. DBP was in dynamic equilibrium in the sediment-water system. DEHP transferred from water to sediments. Our results provide crucial complementary knowledge on bioaccumulation and transfer of PAEs in planktonic food web, and their partitioning in different compartments of waters.

Small volume solid phase extraction method for comprehensive analysis of neonicotinoids, their metabolites, and related pesticides in water

Neonicotinoid insecticides (NEOs) such as clothianidin, imidacloprid, and thiamethoxam are used worldwide. The occurrence of their degradates, for instance, clothianidin-n-desmethyl (CLO-N-DES), clothianidin-urea (CLOU), imidacloprid urea (IMIU) and olefin (IMIO), as well as thiamethoxam urea (THXU), have seldom been documented in water due to the lack of a sensitive analytical method. In this study, a method only requiring 12 mL of water sample was developed and validated to quantify 8 NEOs, 13 metabolites, and 3 related insecticides using solid phase extraction (SPE) coupled with HPLC-MS/MS. The method demonstrated good linearity (r2 > 0.99), with limits of detection (LOD) ranging from 0.16 to 1.21 ng/L and limits of quantification (LOQ) from 0.54 to 4.03 ng/L in water samples. Validation showed accuracy between 70 and 130 % and precision below 15 % for most analytes. The method's performance was comparable to, or better than, existing methods, with the advantage of requiring much smaller sample volumes. Using this method, we monitored the occurrence and seasonal variability of NEOs and their metabolites in various surface water and groundwaters matrices from across Iowa. For example, analysis of water samples from private wells across three Iowa counties detected several NEOs, with notable findings including the first detection of flupyradifurone (FLU) in Iowa well water. Surface water analysis from five locations revealed frequent detection of NEOs and their metabolites, with some concentrations exceeding U.S. EPA chronic toxicity benchmarks for freshwater invertebrates. In addition, this is the first study to demonstrate the occurrence of CLO-N-DES, CLOU, and THX-U in US surface water. The study helps advance analytical methods for NEOs and their metabolites while also highlighting their widespread occurrence in Iowa waters and associated ecological risks, emphasizing the need for more comprehensive monitoring of these compounds.

Construction of a two-dimensional magnetic solid phase extraction microfluidic chip/tandem mass spectrometry platform for the determination of cytarabine in plasma

A novel concept of two-dimensional magnetic solid phase extraction microfluidic chip (2D-MSPE-chip) was proposed, in which two or even more different separation mechanisms of solid phase extraction units were designed and constructed on microfluidic chips in series. The synthesized Fe3O4-UiO-66-C18 was used in the first dimension to retain protein and phospholipid through hydrophobic effect and ZrOP coordination, which could almost eliminate the interference of the matrix effect on the mass spectrum. The second dimensional material utilized Fe3O4-UiO-66-NH2 to enable cytarabine enrichment via π-π and hydrogen bonding. The parameters of 2D MSPE-Chip/tandem MS method such as desorption solvent (5 % acetic acid acetonitrile), loading solvent (20 % acetonitrile), and flow rate for extraction and desorption (10 μL/min) were select. The LOD of the established method for cytarabine in plasma was 0.13 ng/mL, and the linear range was between 2.0 ng/mL and 1000 ng/mL with correlation coefficient (R2 = 0.9991). The matrix effect was −5.0 %. The recovery rate of real samples ranged from 95.5 % to 104.8 %, with RSD ≤ 5.2 %. The chip design was simple and efficient and could be reused, thereby decreasing analysis expenses. It held considerable potential for application in rapid clinical diagnostics and precision medicine.

Bisphenol A in Indian Take-Out Soups: Compliance, Implications and Sustainable Solutions

This research investigates the migration of Bisphenol A (BPA) from packaging containers into take-out vegetable soups and premixed tomato soups through three replicate studies. The samples underwent extraction using solid-phase extraction (SPE) cartridges, followed by separation on a C18 column. BPA concentrations in the soups were assessed at 15, 30, and 45-minute intervals, consistently revealing undetectable levels (&lt;LOQ). Plastic packaging samples, known for BPA utilization in production, remained below the Specific Migration Limit (SML) set at 0.5 mg.kg-1, irrespective of material type or contact conditions. These results, conforming to EC regulations, suggest that food-contact materials (FCMs) in the Indian market pose no apparent health hazards during initial use. The absence of detectable BPA levels is attributed to the limited time-temperature relationship during the study. However, caution is warranted as BPA migration can occur with repeated use, emphasizing the importance of considering material quality and intended use of FCMs. The study underscores the significance of understanding BPA leaching under varied conditions, necessitating further research to explore long-term implications. Overall, the findings provide valuable insights for regulators, manufacturers, and consumers, contributing to the ongoing discourse on food safety and using plastic materials in food packaging.

Enhanced analysis of PAHs in tea using GC–MS/MS with hydrogen carrier gas

A green multiresidue method for PAH analysis was developed using hydrogen as the carrier gas, avoiding harmful solvents and integrating waste-reducing strategies such as µSPE. The use of hydrogen carrier gas in gas chromatography coupled with tandem mass spectrometry (GC–MS/MS) was explored for the enhanced detection of polycyclic aromatic hydrocarbons (PAHs) in black tea. The study demonstrated that hydrogen, as a carrier gas, offers better chromatographic properties than helium or nitrogen. This leads to improved separation of critical pairs using a short run time method. A fast extraction method using micro solid-phase extraction (µSPE) as a clean-up step was developed to analyze 24 PAHs. The extraction method was optimized using a 4 mL 1:1 mixture of ethyl acetate and acetone. The method was validated and demonstrated good recoveries, ranging from 73 % to 113 % for most PAHs, with lower recoveries (50–63 %) observed for high molecular weight PAHs. Reproducibility was also high, with relative standard deviation (RSD) values below 15 %. Linearity and matrix effects were also evaluated, yielding excellent results, with no PAH exhibiting strong matrix effects. Real sample analysis of black tea from various brands and origins revealed the presence of multiple PAHs with concentrations ranging 9.5–39.2 µg/Kg, some exceeding the maximum residue levels set by the European Union. These findings highlight the need for efficient methodologies to monitor PAHs in food products.

Development of a novel second-generation polyester dendritic functionalized graphene oxide for efficient pipette tip micro solid-phase extraction and detection of venlafaxine and desvenlafaxine in urine

Development of a novel second-generation polyester dendritic functionalized graphene oxide for efficient pipette tip micro solid-phase extraction and detection of venlafaxine and desvenlafaxine in urine

Fabrication and application of aminated metal–organic cages doped monolithic column for pipette tip micro solid-phase extraction of eight phenolic compounds in milk

A Zr-based metal–organic tetrahedron (ZrT-1-NH2) doped monolithic column was sythesized and applied for pipette tip micro solid-phase extraction (PT-μSPE) of 8 phenolic compounds. Scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis and N2 adsorption and desorption experiment were employed to characterize the morphology, composition, structure and thermal stability of the monolithic column. The experimental results showed that the monolithic column had good stability and excellent adsorption selectivity for phenolic compounds. The adsorption mechanism was speculated to be π-π stacking and H-bond interaction based on ESP maps. After the extraction conditions were optimized, a PT-μSPE-high performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the detection of 8 phenolic compounds in milk. The PT-μSPE-HPLC-UV method has wide linearities (0.3–1000 μg L−1) (R2 > 0.997), low limits of detection (0.1–0.3 μg L−1), satisfactory recoveries (80.5–113.6 %) and high precision (RSDs < 6.7 %). Thus, the ZrT-1-NH2 doped monolithic column is an ideal medium for the separation and determinaton of phenolic compounds in milk.

Electrochemical determination of nitazoxanide in environmental and pharmaceutical samples using a boron-doped diamond electrode

Consumption of Nitazoxanide (NTZ), a compound belonging to the class of nitrothiazoles, has increased due to its efficiency in treating viral gastroenteritis caused by rotavirus and norovirus “coronavirus disease”. Thus, developing a method capable of monitoring NTZ in wastewater and pharmaceutical formulations is relevant to human health control. However, most methods for NTZ determination are expensive and time-consuming. Hence, we present a fast, efficient, and low-waste method for NTZ monitoring in drugs and water samples using a boron-doped diamond electrode. A 3D-printed electrochemical cell with a capacity of 2 mL was used for all studies. Besides the simplicity of low waste generation, the method provided good analytical performance with a linear range of 2.0–20.0 µmol/L of NTZ, and a limit of detection (LOD) of 0.57 µmol/L. Recovery percentages between 99 and 107 % were obtained to analyze spiked samples. In addition, we demonstrate that the LOD value can be significantly improved by 50 times after applying a pre-concentration step using solid-phase extraction. Therefore, we believe the described approach is a simple and efficient electrochemical method for monitoring NTZ levels in pharmaceutical and environmental samples without laborious sample preparation procedures. This is the first report to describe the use of BDD electrodes for NTZ monitoring and environmental sample analysis using an eco-friendly approach.

Insights into the performance and mechanism of a reinforced lignocellulosic sorbent fabricated from sawdust biomass for multi-tasking application in enrofloxacin removal and monitoring

Natural lignocellulose-based materials have numerous strengths such as abundance, cheap price and biodegradability, which indicates a brilliant prospect for environmental protection. This work aimed to design an efficient sorbent (NaSS-PSD) by pine sawdust (PSD) for the surveillance and management of enrofloxacin (ENR). In the study, sodium styrenesulfonate (NaSS) was chosen as an effective monomer to ameliorate the performance of PSD by graft copolymerization. The removal of ENR by NaSS-PSD was enhanced in comparison with the ungrafted ones under investigated conditions. Pseudo-second-order and Temkin were the best-fitted models to describe the adsorption behavior. For the first time, NaSS-PSD was employed as a novel extractant of solid-phase extraction (SPE) and dispersive solid-phase microextraction (DSPME) to develop accurate, eco-friendly and economic analytical techniques for trace ENR determination. Good linearity and reproducibility were obtained. The limits of detection were 0.41 μg/L for DSPME-HPLC-DAD technique and 0.15 μg/L for SPE-HPLC-DAD technique. These two methods exhibited satisfying practicability when applied to quantify ENR residue in real waters. The study on interfacial interaction mechanism and preferential binding sites suggested that hydrogen bond and π-π interactions took the primary responsibility. Our work provides a good perspective for tailoring natural lignocellulosic biomass to be alternative adsorbents for emerging pollutants.

Novel layered nanofiber mat solid-phase extraction coupled with HPLC-MS/MS for determining 15 biomarkers in plasma and urine of rats after exposure to heat-not-burn tobacco products

Biomarkers of smoke exposure (BoEs) are often used to assess the safety performance of tobacco products; however, there are few methods available for the simultaneous detection of multiple BoEs. A novel dual-layering packed fibers solid phase extraction (DL-PFSPE) was first developed by stacking two layers of nanofiber mats consisting of polystyrene (PS) nanofibers and polypyrrole (PPy) nanofibers separately, which can simultaneously extract polar and non-polar BoEs from plasma and urine samples. Coupled with HPLC-MS/MS, fifteen BoEs including cotinine, 4-(methyl nitrosamine)-1-(3-pyridyl) butanol (NNAL), N-acetyl-S-(2-carbamoyl ethyl)-L-cysteine (AAMA), N-acetyl-S-(3,4-dihydroxy butyl)-L-cysteine (DHBMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (3-HPMA), N-acetyl-S-(3-carboxy-1-methylpropyl)-L-cysteine (3-HMPMA), and phenylmercuric acid (SPMA), 8-isomeric prostaglandin F2α (8-iso-PGF2α), 1-Hydroxy naphthalene (1-OH Nap), 2-hydroxy naphthalene(2-OH Nap), 1-hydroxy phenanthrene (1-OH Phe), 3-hydroxy phenanthrene (3-OH Phe), 2-hydroxy fluorene (2-OH Flu), 9-hydroxy fluorene (9-OH Flu), and 1-hydroxy pyrene (1-OH Pyr) in the plasma and urine of experimental rats exposed to short-term (2 h) smoke exposure can be analyzed. The coefficient of determination (R2) of the working curves for blood and urine samples was greater than 0.99, and the RSDs were 3.4 % (2-OH Nap) to 7.2 % (2-OH Ful) in plasma, 3.3 % (cotinine) to 7.6 % (2-OH Nap) in urine samples. Intra-day and inter-day coefficients of variation were all less than 10 %. The analysis of 15 BoEs in the plasma and urine samples from experimental rats after short-term (2 h) exposure to heat-not-burn tobacco products revealed a significant increase of some BoEs in rats’ bodies. The proposed analytical strategy not only establishes a novel preparation of extraction cartridge but also confirms it as a promising alternative method for the accurate determination of BoEs in plasma and urine samples with good stability and reproducibility.

Dispersive solid phase extraction of 18 PFAS from environmental water samples using a novel MOF-polymeric monolith composite followed by High-Resolution mass spectrometry analysis

Metal-organic frameworks (MOFs) have been broadly coupled with many pretreatment techniques due to their remarkable attributes including high porosity, significantly increased specific surface area, and chemical stability, but their nanoscale dimensions make their handling challenging. To overcome this, a novel MOF-polymeric monolith composite was synthesized and studied as a novel sorbent material in an analytical technique. A rapid and efficient method for the extraction of a mixture of 18 per- and poly-fluoroalkyl (PFAS) compounds from environmental water samples was established based on MOF-polymeric monolith composite assisted dispersive solid phase extraction (d-SPE). The analytical methodology was carried out with the aid of liquid chromatography tandem high-resolution mass spectrometry. Several parameters influencing the extraction efficiency were comprehensively evaluated and optimized. The optimization was based on two processes: the one-variable-at-a-time approach (OVAT) and the central composite design (CCD). Preliminary studies were conducted and the extraction and elution time, as well as the sample volume were evaluated by adopting OVAT approach. The optimal parameters were found to be 15 min for extraction time, 5 min for the elution time and 10 mL as sample volume. Under the optimum conditions, the sample pH, sorbent amount and eluent volume were all evaluated under the design of experiments (DoE). ANOVA demonstrated the suitability of the suggested model with a p-value of less than 0.05 and various diagnostic tests validate the well-fitting results. The software extracted the optimal conditions which were pH = 7, sorbent amount = 10 mg and eluent volume = 750 μL. The method was subsequently validated with respect to accuracy, linearity detection limits and reproducibility. The proposed method presented recoveries over 70 %, method detection limits 1–46 ng/L and relative standard deviations <20 %. Before the implementation of the method in real samples, the “green” character was evaluated using the ComplexGAPI index, indicating the satisfactorily “green” character of the new MOF-based dSPE-LC-HRMS method. Finally, the efficacy of the method for determining PFASs in four environmental water matrices was tested using several matrices of varying complexity, including wastewater effluent, river water, marine water, and runoff.

N,N-Disubstituted 4-Sulfamoylbenzoic Acid Derivatives as Inhibitors of Cytosolic Phospholipase A2α: Synthesis, Aqueous Solubility, and Activity in a Vesicle and a Whole Blood Assay.

Cytosolic phospholipase A2α (cPLA2α) is the key enzyme that initiates the arachidonic acid cascade through which pro-inflammatory lipid mediators can be formed. Therefore, cPLA2α is considered an interesting target for the development of anti-inflammatory drugs. Although several effective inhibitors of the enzyme have been developed, none of them has yet reached clinical application. Recently, we have prepared new 4-sulfamoylbenzoic acid derivatives based on a cPLA2α inhibitor found in a ligand-based virtual screening. The most effective of these compounds were now subjected to further variations in which the substitution pattern on the sulfamoyl nitrogen atom was changed.. The new compounds were tested in vitro in a vesicle assay for cPLA2α inhibition as well as for their water solubility, metabolic stability, and selectivity towards related enzymes. In addition, they were evaluated ex vivo in a whole blood assay in which metabolites of the arachidonic acid cascade formed after activation of cPLA2α were quantified using a combined online dilution/ online solid phase extraction HPLC-MS method. Inhibitors with submicromolar inhibitory in vitro potency were found with favourable water solubility and selectivity. However, their efficacy did not match that of the highly effective, known, structurally related cPLA2α inhibitor giripladib, which was also tested as a reference. One advantage of some of the new compounds compared to giripladib was their significantly improved water solubility. When analyzing the substances in the ex vivo whole blood assay, it was found that the obtained inhibition data correlated better with the in vivo results when the phorbol ester 12-Otetradecanoylphorbol- 13-acetate was used for activation of the enzyme in the blood cells instead of the calcium ionophore A23187. New compounds with good activity towards cPLA2α and reasonable physicochemical properties were identified. Overall, the results obtained could be helpful in the development of clinically applicable inhibitors of this enzyme.

Starch-modified nickel ferrite nanoparticles as a magnetic nano-bio adsorbent for the extraction and determination of lead in water and Moringa oleifera samples

In this work, nickel ferrite magnetic nanoparticles were synthesized using a facile hydrothermal method. The surface modification of the prepared nanoparticles was carried out using cross-linked starch as a good stabilizer and biopolymer. The as-prepared nickel ferrite-starch nano-bio composite was characterized using numerous techniques, and introduced as a novel adsorbent. The initial experimental results indicated that the adsorbent has a good capability to extract lead ions (Pb(II)) from aqueous solutions. Hence, the adsorbent was applied for dispersive magnetic solid-phase extraction of Pb(II) before flame atomic absorption spectrometric detection. Some variables affecting the extraction efficiency such as sample volume (250.0mL), pH (6.5), type and eluent concentration (0.3molL1 nitric acid), amount of the adsorbent (200mg), extraction time (15min), and desorption time (15min) were investigated and optimized. Moreover, the adsorption capacity (35.50mgg1), stability and reusability (80 extraction/desorption cycles), and selectivity of the adsorbent towards the analyte were studied. In the optimized conditions, the linear dynamic range of the constructed calibration graph is between 0.5 and 140.0ngmL1. The limit of detection and limit of quantification of the method are 0.12 and 0.40ngmL1, respectively. The average intra-day and inter-day relative standard deviations (for n=6 and 5.0, 50.0 and 100.0ngmL1 Pb(II) concentration) are 2.02% and 3.72%, respectively. To validate the method, the certified reference material NIST SRM 1643e was analyzed, and the method was used for the pre-concentration and determination of lead ions in different sections of Moringa oleifera medicinal plant and several water samples. The acceptable relative recovery values between 98.0 and 102.7% were attained for the spiked samples, approving the ignorable matrix effect of the method.