High-performance Liquid Chromatography Detection Research Articles

Comparison of determination of sugar-PMP derivatives by two different stationary phases and two HPLC detectors: C18 vs. amide columns and DAD vs. ELSD

Reducing sugars, especially aldoses with their ring structures, have strong reducibility to react with 1-phenyl-3-methyl-5-pyrazolone (PMP) to form sugar-PMP derivatives detected by ultraviolet (UV) detector at 248 nm. In this study, several carbohydrates and some of their alcohols, including 1). seven main monosaccharides, 2). three common disaccharides, 3). two oligosaccharides, and 4). some sweeteners like sugar alcohols were investigated for their reactivities with PMP. Analytes were separated chromatographically by two common high performance liquid chromatography (HPLC) columns and subsequently detected by two tandem detectors. Results pointed out that C18 column had a stronger capacity to separate the reducing sugar-PMP derivatives rather than the sugar themselves. While amide column could only effectively separate the original sugars. These phenomena demonstrated that polarity of reducing sugars decreased after their PMP derivatization. Moreover, both diode array detector (DAD) and evaporative light scattering detector (ELSD) were able to detect the reducing sugar-PMP derivatives, including the PMP-derivative of the oligosaccharide hydrolysate of chitosan, though the DAD exhibits a higher sensitivity than ELSD. In conclusion, carbohydrates themselves are more likely to be efficiently separated by an amide column and detected by ELSD, while DAD combined with a C18 column has more power to determine carbohydrates derivatives.

Rat liver glutathione S-transferase-catalyzed conjugation of glutathione to the endogenous epoxides of oleic acid and cholesterol

cis-9,10-Epoxy-octadecanoic acid (oleic acid epoxide, OAE) and 5α,6α-epoxy-cholesterol (ChE) are endogenous epoxides. Unlike other epoxides, the oxirane groups of OAE and ChE are relatively stable against nucleophiles. OAE lacks toxicity and mutagenicity, while ChE is considered harmful, mutagenic and cancerogenic to animals. In humans, ChE is associated with cancer. The metabolism of OAE and ChE includes hydrolysis by cytosolic and microsomal hydrolases to their diols and glutathione (GSH) conjugation by GSH S-transferases (GST) to form the GSH conjugates (R-SG; R, residue). The GST-catalyzed GSH conjugation of OAE and ChE is poorly investigated. This article reports on the GSH conjugation of OAE, its methyl ester (OAEMe) and of ChE by rat liver homogenate GST. The GSH conjugates of OAE, OAEMe and ChE, i.e., OAE-SG, OAEMe-SG and ChE-SG, respectively, were determined by pre-column derivatization with o-phthaldialdehyde (OPA)/2-mercaptoethanol, high-performance liquid chromatography (HPLC) and fluorescence detection. Complex biphasic kinetics were observed with substrate inhibition of GST activity by OAE, OAEMe and ChE, an optimum pH of about 8.3 for OAE, and no measurable chemical GSH conjugation, underlying the importance of GST for the biotransformation of these epoxides. The results confirm the substrate concentration-dependent kinetic mechanism of GST isoforms first reported by William B. Jakoby (J. Biol. Chem. 1974) for exogenous electrophiles including the epoxide 1,2-epoxy-3-(p-nitrophenoxy)propane and the organic nitrates. This mechanism allows for maximal GST activity that can be achieved under given concentrations of GSH, epoxides and other electrophiles.

Use of high and ultra-high pressure based-processes for the effective recovery of bioactive compounds from Nannochloropsis oceanica microalgae

In this study, the recovery of different bioactive compounds from Nannochloropsis oceanica biomass is proposed using high and ultra-high pressure-based processes. The effect of different pretreatments to weaken cell wall was evaluated before pressurized liquid extraction (PLE). PLE was optimized using an experimental design with ethanol as extraction solvent. Optimum extraction conditions were found at 57 °C and 3 extraction cycles, providing a total carotenoids content of 115.1 ± 0.6 mg/g extract. Then, the residual biomass was extracted using limonene, and an enriched-lipid fraction was obtained. In parallel, ultra-high pressure extraction (UHPE) was applied directly to dry biomass to simultaneously disrupt the cell wall and extract the valuable compounds. Results showed that UHPE technique did not improve carotenoids extraction compared to PLE, although the recovery of polyunsaturated fatty acids was significantly better. Moreover, extracts were chemically characterized using high-performance liquid chromatography detection and gas chromatography coupled to mass spectrometry detection.

Novel metal-organic framework combining with restricted access molecularly imprinted nanomaterials for solid-phase extraction of gatifloxacin from bovine serum

Novel restricted access molecularly imprinted nanomaterials (RAMIPs) were successfully prepared on the surface of metal-organic frameworks (NH2-MIL-125) by surface-initiated atom transfer radical polymerization (SI-ATRP) technology. Then it was applied as a solid phase extraction (SPE) material in analysis of quinolones in bovine serum by HPLC detection. NH2-MIL-125@RAMIPs was empolyed as a sorbent for gatifloxacin (GTFX) and the resulted material has a good binding amounts (86.1 mg g−1), rapid binding kinetic (36 min). The results indicated that the prepared NH2-MIL-125@RAMIPs possess excellent specific recognition for GTFX. Combined with high-performance liquid chromatography (HPLC), the SPE column filled with NH2-MIL-125@RAMIPs was applied to selectively enrich GTFX antibiotic from bovine serum. The recovery of GTFX is between 96.8% and 105.6%, with relative standard deviations of 1.7–3.2% (n = 3). The research results illustrate that the method is successfully applied to the selective enrichment of GTFX in bovine serum. It provides a simple and efficient method for the direct detection of GTFX in bovine serum.

Hybridization of Metal-Organic Frameworks with attapulgite for magnetic solid phase extraction and determination of benzoylurea insecticides in environmental water samples

A magnetic Metal-Organic Frameworks composite material modified with attapulgite was prepared via in situ growth method and characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption and vibration sample magnetometer analysis. It was applied as an efficient adsorbent for the magnetic solid-phase extraction of seven benzoylurea insecticides from environmental water samples couple with high-performance liquid chromatography detection. Under the optimized experimental conditions, the established procedure exhibited low limit of detection ranging from 0.75 to 1.5 µg L−1 and good linear response ranging from 2.5 to 500 µg L−1 with coefficients of determination >0.99. The method recoveries of spiked analytes at the concentrations of 20, 100 and 200 µg L−1 in real water samples were 73.56–99.63% with the relative standard deviations <7.53%. Moreover, the hybrid materials showed excellent reusability and there was no loss observed for the extraction efficiency within five cycles. This study highlighted the potential of functional Metal-Organic Frameworks as efficient adsorbents in sample pretreatment.

Hydrophilic magnetic molecularly imprinted nanobeads for efficient enrichment and high performance liquid chromatographic detection of 17beta-estradiol in environmental water samples

Novel magnetic molecularly imprinted nanobeads for 17β-estradiol (E2), namely, E2-MMINs, were synthesized by molecularly imprinted polymers on the surface of magnetic nanobeads in aqueous solvents. The hydrophilic nanobeads were set up by adopting carboxyl group-functionalized Fe3O4 nanoparticles as carriers, E2 as template molecule, and dopamine as functional monomer. The synthesized E2-MMINs were investigated in different aspects including synthesis conditions, physical and chemical properties, and adsorption conditions. The experimental results show that the E2-MMINs present not only thin imprinting layers, stable crystal form, and fast magnetic separation ability, but also rapid kinetics (20 min), high binding amount (41.48 mg g−1), satisfactory specificity (imprinting factor = 8.07), and favorable reusability (adsorption efficiency > 94.8% after reusing for 10 times). Moreover, the method employing E2-MMINs combined with high performance liquid chromatography for the specific enrichment and determination of trace E2 has been developed with the low LOD (0.008 μg L−1), and the application in environmental water samples has been proved. This work demonstrates that the proposed synthetic strategy is highly promising to the synthesis of hydrophilic nanobeads for efficient enrichment and detection of target molecule E2.

Preparation of poly (KH570-co-DVB) microspheres and application in HPLC for separation of benzene and benzene homologs

High-performance liquid chromatography (HPLC) is one of the most widely used separations and analysis methods, which has become an indispensable part of the separation and detection of mixtures, qualitative and quantitative analysis and other scientific research and social production fields. Because of the decisive effect of the chromatographic column on analysis and separation, it has become the core of research in the chromatographic system. In the past decades, the research and development of new chromatographic column stationary phase have been highly concerned. Monodisperse polymer microsphere, because of its special large pore structure, has good permeability and high specific surface area, which can be used as special materials in various fields, such as adsorption materials in the separation process, HPLC column packing, catalyst carrier, preparation template of nanomaterials and nuclear fusion targeting materials. When it is used in HPLC, because of the good permeability of microspheres, it can effectively improve the separation efficiency and performance. In this article, based on the previous work, a number of new polymer microspheres were prepared, and the prepared microspheres were used for the separation and detection of HPLC, and their physical and chemical properties were studied.

&lt;p&gt;Effect of &lt;em&gt;Malus asiatica&lt;/em&gt; Nakai Leaf Flavonoids on the Prevention of Esophageal Cancer in C57BL/6J Mice by Regulating the IL-17 Signaling Pathway&lt;/p&gt;

BackgroundThe aim of this study was to observe the preventive effect of flavonoids extracted from Malus asiatica Nakai leaves (FMANL) on esophageal cancer in mice, especially the ability of FMANL to regulate the interleukin 17 (IL-17) signaling pathway during this process.Materials and MethodsThe C57BL/6J mice were treated with 4-nitroquinoline N-oxide (4NQO) to induce esophageal cancer, and the visceral tissue index and the serum and esophageal tissue indexes of mice were used to verify the effect of FMANL.ResultsThe experimental results showed that FMANL can effectively control the changes in visceral tissue caused by esophageal cancer. FMANL could increase the cytokine levels of interleukin 10 (IL-10), monocyte chemotactic protein 1 (MCP-1) and decrease the cytokine levels of tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), interleukin 6 (IL-6), and interleukin 12p70 (IL-12p70) in serum of mice with esophageal cancer. FMANL could also reduce CD3+, CD4+, and CD8+ and enhance CD19+ mouse peripheral blood lymphocytes. The results of qPCR and Western blot analysis showed that FMANL could down-regulate the mRNA and protein expression levels of IL-17, interleukin 23 (IL-23), interleukin 1 beta (IL-1β), chemokine (C-X-C) ligand 1 (CXCL1), chemokine (C-X-C) ligand 2 (CXCL2), S100 calcium-binding protein A8 (S100A8), S100 calcium-binding protein A9 (S100A9), matrix metalloprotein 9 (MMP-9), and matrix metalloprotein 13 (MMP-1) in mice with esophageal cancer. High-performance liquid chromatography (HPLC) detection showed that FMANL contained 10 chemicals, including rutin, hyperoside, isoquercitrin, dihydroquercetin, quercitrin, hesperidin, myricetin, baicalin, neohesperidin dihydrochalcone, and quercetin.ConclusionIt could be concluded that FMANL can effectively prevent experimentally induced esophageal cancer in mice, and its effects might be obtained from 10 compounds present in FMANL.

Residue analysis and kinetics modeling of thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin in apple tree bark using QuEChERS/HPLC-VWD.

Winter is the key period for the control of apple diseases, and fungicides are needed to protect the trunk or main branches. Fungicide residue in apple tree bark is an important basis for the action of the pesticide, but there are no reports on analytical methods or dissipation patterns. In this work, thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin were selected as typical fungicides and a new QuEChERS-HPLC-VWD(QuEChERS extraction followed by high-performance liquid chromatography detection with a variable wavelength detector) analytical method was developed to estimate their residue kinetics in apple tree bark during the winter months. In the pretreatment step, the sorbent for the clean-up of extracts was optimized as 60 mg/ml primary secondary amine and a gradient-elution model followed by a variable wavelength detection was developed for instrumental analysis. Then this method was validated and applied to the analysis of apple tree bark samples with the linearity range of 0.010-50.00 mg/L, quantification limit range of 0.028-0.080 mg/kg and recovery range of 86.1-101.4%. The dissipation kinetics of thiophanate-methyl and pyraclostrobin could be described by the first-order and two-phase kinetics models, respectively. For carbendazim and tebuconazole, two new models were developed to describe their residue kinetics.

Effects of Different Stress Treatments on the Total Terpene Trilactone Content and Expression Levels of Key Genes in Ginkgo biloba Leaves

As unique secondary metabolites of Ginkgo biloba L. and relics of Ginkgoaceae, terpene trilactones (TTLs) possess great medicinal value. In this study, we investigated the effects of ultraviolet (UV) irradiation, cold stress (4 °C), and exogenous hormone treatment on TTLs and key genes expression in ginkgo leaves in annual potted ginkgo seedlings subjected to different stress treatments. The processing conditions were as follows: UV treatment (1500 μJ/m2) for 0, 8, 16, 24, and 48 h; cold stress at 4 °C, 400 µmol photons m−2 s−1; 100 μM abscisic acid (ABA); 100 μM methyl jasmonate (MeJA); 10 mM salicylic acid (SA); and 10 mM ethephon (ETH) treatments for 0, 2, 4, 6, and 8 days. Results of evaporative light-scattering detector–high-performance liquid chromatography showed that UV, cold stress, ABA, SA, MeJA, and ETH treatments increased the TTL content at various levels and up to 21.9%. The relationships among the expression levels of the key enzyme genes GbDXS, GbGGPPS, GbLPS, and GbMVD in the TTL biosynthesis pathway were also analyzed. Changes in the TTL content and expression levels of the key genes were significantly and positively correlated with TTL content. UV, cold stress, ABA, SA, MeJA, and ETH were found to increase the TTL content by upregulating the expression of the key genes. This study aimed to reveal the molecular mechanism through which TTLs are synthesized. The results can also provide theoretical guidance for the application of treatment methods to increase TTL content.

Facile synthesis of conjugated microporous polymer with spherical structure for solid phase extraction of phenyl urea herbicides

A carbazolic conjugated microporous polymer (designated as CZ-CMP) was successfully synthesized through Scholl reaction of carbazole with 1, 3, 5-triphenylbenzene. The CZ-CMP was characterized by FT-IR spectrum, X-ray diffraction, nitrogen sorption isotherms, and scanning electron microscopy. The characterization results showed that the CZ-CMP had a spherical structure with high surface area and good microporosity. Its adsorption performance was investigated by applying it as an adsorbent for the solid phase extraction (SPE) of phenyl urea herbicides (PUHs) (metoxuron, chlortoluron, isoproturon, monolinuron and buturon) from tea drinks samples prior to high performance liquid chromatographic detection. The CZ-CMP displayed high extraction efficiency for the PUHs, and the primary factors affecting the SPE efficiency including the type and volume of the eluent, sample solution pH, sample loading rate and sample volume were optimized. Under the optimized conditions, a good linear response for the analytes was observed in the range of 0.10–80.0 ng mL−1 with correlation coefficients (r) from 0.9937 to 0.9997. The limits of detection were measured to be in the range of 0.02–0.30 ng mL−1 and the limits of quantitation were in the range of 0.06–0.9 ng mL−1. The developed method was successfully applied for the determination of the five PUHs in four different kinds of drinks with the method recoveries between 83.7% and 118% and the relative standard deviations between 1.0% and 10%. Besides, the application potential of the CZ-CMP was evaluated by using it to extract different types of the organic compounds including some phthalate eaters (PAEs), chlorophenol (CPs), nitroimidazoles and polycyclic aromatic hydrocarbons (PAHs). The results indicated that the CZ-CMP had strong adsorption ability for the compounds with more hydrogen bonding sites and moderate hydrophobicity.

An automated assessment system of limits of detection and quantitation in gradient high-performance liquid chromatography with ultraviolet detection

A previous paper of this series of study put forward a basic model of an automated system for predicting detection limits and showed its application to a simple example of isocratic high-performance liquid chromatography (HPLC). This paper describes an expansion of the basic system into gradient HPLC. The most serious problem with the expansion is a long-term variation in backgrounds, called gradient baseline drifts, which in theory cannot be covered by a noise model (stationary random process) of the original system. This paper demonstrates that the above problem can be solved with modifying a parametrization procedure of the noise model. The essential role of the system is to predict the standard deviation (SD) of measurements at low concentrations from a chromatogram without repeated measurements of real samples. Laboratory-made software enables the automated assessment of the limits of detection and quantitation for each of chromatographically separated signals in a single run. Simulated background noise which consists of the stationary noise model with linear slopes is used to confirm the accuracy and reproducibility of the automated prediction. A gradient HPLC determination for cefaclor is taken as an example. The parametrization modification improves the correlation coefficient, r2, between the observed and theoretical distributions of the area measurements from 0.373 to 0.966. The statistical confidence levels of the theoretically predicted relative SDs for cefaclor were verified by comparing them with those obtained by repeated experiments (r2 = 0.989). The limits of detection (= 3.3 × SD = 18.0 µg/L) and quantitation (= 10 × SD = 54.7 µg/L) for cefaclor have signal-to-noise ratios close to the commonly adopted values, 3 and 10, respectively.

Preparation of a Magnetic Multiwalled Carbon Nanotube-Gold Nanoparticle Hybrid Material for the Efficient Extraction of Triazine Herbicides from Rice

A facile and efficient analytical method for determination of four triazine herbicides (atrazine, ametryn, terbutryn, and terbuthylazine) from rice was developed by employing a magnetic multiwalled carbon nanotube-gold nanoparticle material (mMWCNT@Au) as the solid-phase extraction adsorbent, followed by high performance liquid chromatography (HPLC) detection. The mMWCNT@Au was fabricated based on a simple solvothermal reduction method. The prepared material was characterized by transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy. Parameters influencing the extraction efficiency (the type and volume of extraction solvent, mass of mMWCNT@Au, extraction time, volume of desorption solvent and desorption time) were systematically investigated and optimized. Under the optimal extraction and determination conditions, the calibration curves were linear over the concentration range of 2.5 to 1000 μg kg−1 with correlation coefficients in the range of 0.9980 to 0.9998. The limits of detection for atrazine, ametryn, terbutryn, and terbuthylazine were 1.05, 0.97, 1.19, and 1.22 μg kg−1, respectively. The intra-day and inter-day recoveries were in the ranges from 88.3 to 105.4% and 88.2 to 101.8%, respectively. The relative standard deviations ranged from 4.3 to 9.0% and 4.5 to 9.1%, respectively. The proposed method has been shown to be a reliable alternative approach for the determination of triazine herbicides in rice samples.

91 The production of sulfated 16-androstene steroids by porcine Leydig cells and their potential role in the development of boar taint

Abstract Boar taint is a meat quality issue characterized by an off-odour or off-flavour in pork caused primarily by the accumulation of androstenone in the fat, but sensory estimates of boar taint do not always correlate with fat androstenone concentrations. However, these evaluations examine the sensory qualities of both the fat and lean tissue of heated pork products. Sulfated metabolites of androstenone are polar compounds that are abundantly produced by the Leydig cells of the testes, which may accumulate in more hydrophilic lean tissue. Therefore, the purpose of this study was to investigate the testicular metabolism of androstenone, which is responsible for the high production of sulfated androstenone metabolites. Leydig cells were isolated from 7-month-old Yorkshire, Duroc and terminal cross [Duroc x (Landrace x Yorkshire)] (n = 3) boars and incubated with radiolabeled androstenone for 8 hours. The proportion of sulfated metabolites produced was quantified using reverse phase high performance liquid chromatography (HPLC) and radioisotope detection. The sulfated metabolites were subsequently identified using liquid chromatography-mass spectrometry (LC-MS/MS). Statistical analysis was conducted using a one-way ANOVA in SAS. Following isolation and analysis with LC-MS/MS, the sulfated metabolites were identified as androstenol-3-sulfate and two major sulfated forms of androstenone. Additionally, removal of the sulfate group from these two sulfated forms of androstenone returned the parent compound androstenone, and not a hydroxylated metabolite. The average production of sulfated androstenol produced across all boars was 52.1±8.6%, which was not significantly different (P = 0.7) from the average production of sulfated androstenone (47.9±8.6%). The results of this study indicate that androstenone is directly sulfated, which allows these sulfated metabolites to function as steroid reservoirs that can enzymatically regenerate free androstenone within hydrophilic lean tissue. Alternatively, these metabolites may accumulate in the lean tissue, which we are proposing as a novel mechanism that contributes to the development of boar taint.

Humic acid functionalized hyperbranched polytriazine based dispersive solid‐phase extraction for acaricides determination in tea matrix

Hyperbranched polytriazine functionalized with humic acid was prepared and developed as new sorbents for dispersive solid-phase extraction of three acaricides (clofentezine, fenpyroximate, and pyridaben) in tea samples combined with high-performance liquid chromatography detection. The sorbents were characterized by scanning electron microscopy, energy dispersive spectroscopy, Zeta-potential, and Fourier transform infrared spectroscopy. The extraction parameters (extraction time, ionic strength, desorption conditions) were optimized. The adsorption mechanism was evaluated utilizing Fourier transform infrared spectra. Under optimum conditions, satisfactory analytical performances were achieved, which included high precision (1.33-9.62%), low limits of detection (0.19-3.54 µg/L), and wide linear range (2.5-500 µg/L) for the analysis of the acaricides. Moreover, the proposed method proved highly effective for the determination of acaricides in tea samples, with the relative recoveries in the range of 65.20-108.13% and relative standard deviations<9.87%. The method has great application potential for the detection of acaricides in tea samples.

Monitoring steady production of 1,3-propanediol during bioprospecting of glycerol-assimilating soil microbiome using dye-based pH-stat method.

In this investigation, a dye-based pH-stat method was devised for monitoring steady production of 1,3-propanediol (1,3-PDO) during bioprospecting of glycerol-assimilating soil microbiome. Soil samples were collected from two potential sites of CSIR-IIP, India. Selective enrichment of microbial consortia was done using the glycerol-based medium at initial stage, followed by purification to isolated colonies, after positive high-performance liquid chromatography detection of 1,3-PDO in the fermentation broth. When the purified isolated were re-tested for 1,3-PDO production, only two isolates namely Isolate 1 and Isolate 3 were capable of producing the targeted product preferably under anaerobic conditions. Based on better 1,3-PDO fermentation efficiency (Isolate 3, 22% vs Isolate 1, 4·48%) and acetic acid as the only major by-product, Isolate 3 was shortlisted for further studies. A dye-based technique was devised in which bromothymol blue was incorporated into the medium to monitor the pH drop due to acetic acid formation and hence change in colour. Visual change in colour helped in intermittent pH restoration. During fermentation, with pH stat being 8-8·5, Isolate 3 at 32°C yielded 0·67molmol-1 1,3-PDO within a short span of 12h only with an initial concentration of glycerol being 20gl-1 . Phylogenetic analysis revealed that Isolate 3 shared 95·8% homology with Citrobacter freundii CFNIH1 and hence designated as C. freundii IIP DR3. This study demonstrated that during bioprospecting glycerol-assimilating microbiome, dye-based technique can be successfully employed. This technique can further be exploited to monitor consistent production of all microbial secondary metabolites that accompanies acid production. Incorporation of 'Bromothymol blue' can visually help in the identification of pH drop in the medium, so that pH stat can be easily maintained during 1,3-PDO production from glycerol especially under shake flask conditions.

Dispersive solid-phase extraction adsorbent of methamphetamine using in-situ synthesized carbon-based conductive polypyrrole nanocomposite: focus on clinical applications in human urine.

Determination of methamphetamine is of great importance in clinical and forensic laboratories because there are low dosages of drugs in the biological media and social problems created due to the methamphetamine consumption. Polymeric carbon based-nano composites are reasonable candidates for dispersive solid phase extraction method due to facial and affordable synthesis process and high selectivity and sensitivity. Nano graphene oxide polypyrolle composite was synthesized and employed as dispersive solid-phase extraction adsorbent for methamphetamine extraction from complex urine matrix. Full characterization of the prepared nano graphene oxide polypyrolle composite was completed and the influential extraction parameters were investigated through one-parameter-at-a-time method. High-performance liquid chromatography detectors were applied as detection and quantification instrument. The optimized extraction parameters included 300 µL of methanol, 10min of extraction and desorption time, 6000 stirring rate, urine pH value of 10, 60mg of adsorbent, and 6mL of urine volume. After outlining the calibration curve, the linear range of the method was considered as 30-800ng/mL. The detection limit for the suggested method was 9ng/mL. The analysis of addicted subjects with the proposed method confirmed the utility of the method in different analytical and clinical laboratories.

A flower-like hybrid material composed of Fe3O4, graphene oxide and CdSe nanodots for magnetic solid phase extraction of ibuprofen prior to its quantification by HPLC detection.

A flower-like Fe3O4/GO/CdSe nanodot magnetic hybrid material was produced and applied to magnetic solid-phase extraction of ibuprofen from pharmaceuticals, water, and urine samples. The material was characterized by X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy and SEM-EDX. The pH value, volume of sample solution, amount of sorbent, type and volume of elution solvent and extraction time were optimized. Following elution with acetone, ibuprofen was quantified by HPLC-DAD detection. The recoveries of ibuprofen from spiked real samples ranged between 87 and 109%, and the intra-day and inter-day relative standard deviations from 1.25 to 3.02%. The limit of detection, limit of quantification and preconcentration factor are 0.36ng·mL-1,1.20ng·mL-1 and 150, respectively. Graphical abstract Schematic representation of the combination of flower-like Fe3O4/GO/CdSe nanodot-based magnetic solid phase extraction (MSPE) and high-performance liquid chromatography (HPLC) procedure for the extraction and analysis of ibuprofen in pharmaceuticals, water, and urine samples.

Потенциометрическая мультисенсорная система на основе перфторированных мембран и допантов с протоноакцепторными свойствами для определения прокаина и лидокаина в комбинированном препарате

Разработана потенциометрическая мультисенсорная система с перекрестно чувствительными ПД-сенсорами (аналитический сигнал – потенциал Доннана) на основе перфторированных сульфокатионообменных мембран МФ-4СК и Nafion, содержащих 3 мас.% SiO2, поверхностно модифицированного 10 мол.% 3-аминопропила, и 2.4 мас.% ZrO2 для совместного определения катионов прокаина и лидокаина в диапазоне концентраций от 1.0·10-4 до 1.0·10-2 М. Пределы обнаружения ионов прокаина и лидокаина с помощью предложенной мультисенсорной системы составили1.0·10-6 и 4.5·10-5 М, соответственно. Относительная погрешность и относительное стандартное отклонение определения катионов прокаина в комбинированном фармацевтическом препарате составили 0.5-11 и 4-11 %, катионов лидокаина – 5-6 и 10-12%, соответственно.

MgO-ZnO/carbon nanofiber nanocomposite as an adsorbent for ultrasound-assisted dispersive solid-phase microextraction of carbamazepine from wastewater prior to high-performance liquid chromatographic detection

A simple, rapid, and efficient ultrasound-assisted dispersive solid-phase microextraction (UA-DSPME) method was developed for the preconcentration of carbamazepine (CBZ) in wastewater prior to high-performance liquid chromatography coupled with diode array (HPLC-DAD) determination. The carbon nanofibers coated with magnesium oxide-zinc oxide (MgO-ZnO@CNFs) nanocomposite was used as an efficient adsorbent in magnetic dispersive solid-phase microextraction method. The structural and morphological properties of the nanocomposite were characterized by scanning electron microscopy and energy dispersive spectroscopy, transmission electron microscopy, X-ray diffractometer, and Fourier transform infrared spectroscopy. The surface area was investigated using Brunauer–Emmett–Teller. Several factors (such as pH, mass of adsorbent, extraction time, and eluent volume) that affect extraction and preconcentration of CBZ were also assessed and optimized using response surface methodology based on central composite design. Under optimal conditions, the limits of detection (LOD) and quantification were 0.08 μg L−1 and 0.29 μg L−1, respectively. The calibration curve constructed after preconcentration of seven successive standards was linear in the concentration range of 0.3–800 μg L−1 with the correlation coefficient of 0.9922. The intra-day and inter-day precisions expressed in terms of relative standard deviation were 1.4% and 4.2%. A preconcentration factor of 490 was achieved, and the method was applied for the analysis of spiked wastewater. Satisfactory recoveries ranging from 97.8 to 102% were obtained.