Flow Injection Analysis
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A simple and rapid method for determining diclofenac in a sequential injection system was developed for the selective and sensitive on-line determination of the analyte in sample from a metabolic study. The fluorescence properties of complexes of 13 types of cyclodextrins and their derivatives, including salts, were studied off-line, while two of the complexes were then used in the flow conditions. Optimisation was carried out with (2-hydroxypropyl)-γ-cyclodextrin, which is fluorescent and the intensity of its complex with diclofenac was found to be lower. In the flow system, we tested different types of mixing of zones and stop-flow periods. Simple mixing using flow reversal and a 1-min stop-flow in the holding coil were sufficient to rapidly determine diclofenac, even at low concentrations with a limit of quantitation of 1 × 10-6 mol/L. The relationship between fluorescence intensity and diclofenac concentration showed a different pattern in the two intervals: decreasing in the range of 1-5x10-7 mol/l and linearly increasing in the range of 1-5x10-6 mol/l, which was used for analysis. Real samples from a metabolic activity study based on the activation of xenobiotics recognition receptors were analysed, and the results were compared with off-line liquid chromatography/mass spectrometry measurements. The differences corresponded to the complexity of the matrix and were not significant. The trend of diclofenac metabolism was obvious. The developed method is prepared for the fully automated, real-time monitoring of the metabolic study with more frequent sampling than just once daily and the prediction of sample collection for the mass spectrometric determination of diclofenac metabolites.
- Klíčová slova
- Automation, Cyclodextrin complex, Diclofenac, Fluorescence, Sequential injection analysis,
- Publikační typ
- časopisecké články MeSH
New polyamide (PA) homopolymers and copolymers nanofibers with different alkyl chain lengths as novel materials have been investigated for the automation of on-line sample preparation step and extraction of polycyclic aromatic hydrocarbons (PAHs) from the environment. PA 4/6 nanofiber copolymer showed the highest extraction yield of tested analytes and comparable performance with commercial reversed phase C18 sorbent. Our study presents an automation of on-line solid phase extraction method coupled with ultra-high performance liquid chromatography with fluorescence detection for the analysis of nine PAHs in river water. The optimal conditions included 50 μL injection volume, washing with 10 % acetonitrile at a flow rate of 1.0 mL min-1 for 1 min, followed by backflush elution of analytes using a gradient of acetonitrile (from 60 % to 74 %) in water at 1.5 mL min-1 over 12.25 min on a YMC-Triart PFP column (150 × 4.6 mm, 3 μm particle size). The total analysis time, including extraction, separation, and column equilibration, was 14 min. This method provides excellent analytical performance, with linearity ranging from 0.01 to 0.5 μg L-1 for acenaphthene, anthracene, pyrene, chrysene, and 0.05-0.3 μg L-1 for benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, indeno(c,d)pyrene and benzo(g,h,i)perylene, with coefficients of determination (R2) ranging 0.9989-0.9999. The limits of detection and quantification were 0.003-0.01 and 0.01-0.05 μg L-1, respectively. The recoveries were between 92 and 105 %, with RSD 1.53-6.66 %. The polyamide-based sorbent requires no modification and can be inexpensively prepared as homogeneous mats by electrospinning. It can be cut and manually packed into a column or filtration device, allowing for easy replacement, when needed, with inter-columns repeatability of RSD <13 %. In addition, a single extraction column can be reused repeatedly.
- Klíčová slova
- Automation, Copolymers, Liquid chromatography, On-line solid phase extraction, Polyamide homopolymers, Polycyclic aromatic hydrocarbons,
- Publikační typ
- časopisecké články MeSH
Automation and hyphenation of multiple steps were used for the sensitive determination of xenobiotic residues in surface waters. The online hyphenated sequential injection analysis instrumentation used surface-modified microfibrous sorbent for the effective solid phase extraction of 1.0 mL of sample into 100 μL zone, then subjected to the reversed-phase ultra-high performance liquid chromatography (SIA-SPE-UHPLC). The SPE column was packed with polypropylene microfibers and coated with polydopamine by rinsing with the dopamine solution. The freshly prepared column was used for highly reproducible extraction of more than 200 samples in the SIA-SPE-UHPLC method. The matrix calibration covered the expected range with limits of detection in the range 0.1-0.9 μg/L. The method precision was <13 % RSD (at 3 concentration levels), and the method accuracy was in the range 86.5-114.8 %. The sample throughput of the method was 5 samples/hour when the separation took 12 min, including a 5 min SPE step of the next sample run in parallel. The performance of the developed method was demonstrated with the analysis of fifteen river water samples spiked with eleven residues of xenobiotics (ivermectin, fenbendazole, praziquantel, ibuprofen, diclofenac, 17α-ethynylestradiol, androstenedione, carbamazepine, omeprazole, sotalol, and caffeine) at the levels typical for such monitoring. Initial sample treatment prior to the automated analysis consisted only of methanol addition, pH adjustment, and centrifugation. The innovations in the manifold and process that contribute to the modern and effective analysis of environmental samples are discussed.
BACKGROUND: Determination of critical quality attributes (CQAs) of pharmaceutical monoclonal antibodies (mAbs) is an essential part of quality control. Commonly, for each CQA, a separate analytical method and setup is required, making assessment of multiple CQAs time-consuming and labour-intensive. This typically involves offline purification and diverse protein digestion steps, in combination with multiple liquid-chromatographic modes. We developed an integrated, fully online multidimensional platform for direct analysis of mAbs in cell culture fluid (CCF) at an intact, subunit and peptide level from a single injection. RESULTS: This paper focuses on the online middle-up and bottom-up workflows. The platform combines Protein A affinity chromatography (ProtA), immobilized enzyme reactors (IMERs), reversed-phase liquid chromatography (RPLC) and high-resolution mass spectrometry (MS) for characterization of mAbs. Online ProtA was used to isolate mAbs directly from CCF. Subsequent online digestion of isolated mAb was accomplished by IMERs featuring either the proteases IdeS or trypsin. Between ProtA and IMERs, buffer exchange and pH adjustment were achieved using a strong cation-exchange (SCX) trap column. RPLC-MS analysis of F(ab)'2 and Fc/2 fragments obtained after IdeS digestion provided information on mAb glycoform compositions and the potential presence of PTMs and subunit variants. RPLC-MS/MS analysis of trypsin-digested peptides provided over 95 % coverage of the mAb's amino acid sequence, but also identification and localization of modifications related to e.g. oxidation and deamidation. Comparisons with established offline methods were made. The overall capacity of the system to perform intact, middle-, and bottom-up analyses in parallel from a single injection is demonstrated for an industrially-relevant mAb in CCF. SIGNIFICANCE: The developed multidimensional platform enables the simultaneous characterization of multiple fractions from a single ProtA-isolated mAb band at intact, middle-up, or bottom-up level using various LC modes at a substantially reduced analysis time.
- Klíčová slova
- Critical quality attributes, IMERs, Multi-dimensional characterization, Protein liquid chromatography, mAb,
- MeSH
- buněčné kultury MeSH
- CHO buňky MeSH
- chromatografie afinitní MeSH
- chromatografie s reverzní fází MeSH
- Cricetulus MeSH
- lidé MeSH
- monoklonální protilátky * analýza chemie MeSH
- průběh práce MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- monoklonální protilátky * MeSH
RATIONALE: Data are required for SIFT-MS analysis of perfluoroalkyl and polyfluoroalkyl substances (PFAS), which are persistent in the environment and cause adverse health effects. Specifically, the rate coefficients and product ion branching ratios of the reactions of H3O+, NO+, O2 +•, O-•, OH-, O2 -•, NO2 - and NO3 - with PFAS vapours are needed. METHODS: The dual polarity SIFT-MS instrument (Voice200) was used to generate these eight reagent ions and inject them into the flow tube with N2 carrier gas at a temperature of 393 K. Vapours of pentafluoropropionic acid, heptafluorobutyric acid, nonafluoro-1-hexanol, perfluoro-2-methyl-2-pentene, perfluorohexanoic acid, perfluoro(2-methyl-3-oxahexanoic) acid, tridecafluoro-1-octanol and nonafluorobutane-1-sulfonic acid were introduced in dry and humid air. Full-scan mass spectra were collected for all reagents at variable PFAS concentrations and analysed numerically. RESULTS: Rate coefficients were determined for 64 reactions, for which 55 positive and 71 negative product ions were identified. The branching ratios for the primary reaction channels were extracted from the data, and the secondary chemistry with H2O molecules was qualitatively assessed. The thermochemical data were calculated for the H3O+ reactions using density functional theory (DFT). CONCLUSIONS: An important observation is that secondary reactions with water molecules remove the positive product ions, making them unsuitable for practical SIFT-MS analysis of PFAS vapours. In contrast, most negative reaction product ions are not significantly affected by humidity and are thus preferred for the SIFT-MS analyses of PFAS substances in various gaseous matrices.
- Klíčová slova
- ion molecule reactions, perfluoroalkyl and polyfluoroalkyl substances (PFAS), selected ion flow tube,
- Publikační typ
- časopisecké články MeSH
A sensitive method for Rh determination was developed by coupling photochemical vapor generation (PVG) for sample introduction to inductively coupled plasma mass spectrometry (ICPMS). PVG was conducted in a thin-film flow-through photoreactor operated in a flow injection mode from a photochemical medium comprising 10 M HCOOH. PVG efficiency was substantially enhanced by the addition of 10 mg L-1 Cu2+ and 5 mg L-1 Co2+ as mediators as well as 50 mM NaNO3. The volatile product (likely Rh(CO)4H) was found to be less stable when in prolonged contact with the liquid medium at the output from the photoreactor. Hence, further enhancement was achieved by introducing an Ar carrier gas near the exit of the photoreactor to minimize the interaction of volatile species with the liquid medium. Despite PVG efficiency reaching only 15%, measurement at the ultratrace level (20 ng L-1) was characterized by very good repeatability of peak area response (2.9%) and outstanding limits of detection (13 pg L-1, 6.5 fg absolute) using He in the collision cell. Interferences from potential coexisting metals, inorganic acids, and their anions were investigated. Accuracy was verified by analysis of OREAS 684 (Platinum Group Element Ore) and SRM 2556 (Used Auto Catalyst) following peroxide fusion for sample preparation. Application to the direct analysis of real river and lake water samples and reference materials AQUA-1 and SLRS-6 demonstrated excellent selectivity of the PVG-ICPMS methodology over conventional pneumatic nebulization-ICP(MS)/MS, the results of which were seriously biased by polyatomic interferences, especially from Sr and Cu, despite the use of various reaction/collision cell modes.
- Publikační typ
- časopisecké články MeSH
New voltammetric and flow amperometric methods for the determination of guaifenesin (GFE) using a perspective screen-printed sensor (SPE) with boron-doped diamond electrode (BDDE) were developed. The electrochemical oxidation of GFE was studied on the surface of the oxygen-terminated BDDE of the sensor. The GFE provided two irreversible anodic signals at a potential of 1.0 and 1.1 V (vs. Ag|AgCl|KCl sat.) in Britton-Robinson buffer (pH 2), which was chosen as the supporting electrolyte for all measurements. First, a voltammetric method based on differential pulse voltammetry was developed and a low detection limit (LOD = 41 nmol L-1), a wide linear dynamic range (LDR = 0.1-155 μmol L-1), and a good recovery in the analysis of model and pharmaceutical samples (RSD <3.0 %) were obtained. In addition, this sensor demonstrated excellent sensitivity and reproducibility in the analysis of biological samples (RSD <3.2 %), where the analysis took place in a drop of serum (50 μL) without pretreatment and additional electrolyte. Subsequently, SP/BDDE was incorporated into a flow-through 3D printed electrochemical cell and a flow injection analysis method with electrochemical detection (FIA-ED) was developed, resulting in excellent analytical parameters (LOD = 86 nmol L-1, LDR = 0.1-50 μmol L-1). Moreover, the mechanism of electrochemical oxidation of GFE was proposed based on calculations of HOMO spatial distribution and spectroelectrochemical measurements focused on IR identification of intermediates and products.
- Klíčová slova
- Boron-doped diamond electrode, Flow injection analysis with electrochemical detection, Guaifenesin, Screen-printed sensor, Spectroelectrochemistry, Voltammetry,
- MeSH
- bor * chemie MeSH
- diamant * chemie MeSH
- elektrochemické techniky * metody přístrojové vybavení MeSH
- elektrody * MeSH
- guaifenesin * analýza chemie MeSH
- lidé MeSH
- limita detekce MeSH
- oxidace-redukce MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- bor * MeSH
- diamant * MeSH
- guaifenesin * MeSH
Open Porous Media (OPM) Flow is an open-source reservoir simulator used for solving subsurface porous media flow problems. Focus is placed here on carbon sequestration and the modeling of fluid flow within underground porous reservoirs. In this study, a sensitivity analysis of some input parameters for carbon sequestration is performed using six different uncertain parameters. An ensemble of model realizations is simulated using OPM Flow, and the model output is then calculated based on the values of the six input parameters mentioned above. CO2 injection is simulated for a period of 15 years, while the post-injection migration of CO2 in the saline storage aquifer is simulated for a subsequent period of 200 years, leading to a final analysis after 215 years. The input parameter values are generated using the quasi-Monte Carlo (QMC) method in the region of interest, following specified patterns suitable for analysis. The optimal convergence rate for quasi-Monte Carlo is observed. The aim of this study is to identify important input parameters contributing significantly to the model output, which is accomplished using sensitivity analysis and verified through symbolic regression modeling based on machine learning. Global sensitivity analysis using the Sobol sequence identifies input parameter 3, 'Permeability of shale between sand layers,' as having the most influence on the model output 'Secondary Trapped CO2.' All regression models, including the simplest and least accurate ones, incorporate parameter 3, confirming its significance. These approximations are valid within the designated area of interest for the input parameters and are easily interpretable for human experts. Sensitivity analysis of the developed time-dependent carbon sequestration model shows that the significance of each physical parameter changes over time: Sand porosity is more significant than shale permeability for roughly the first 120 years. Consequently, the presented results show that simulation timescales of at least 200 years are necessary for carbon sequestration evaluation.
- Klíčová slova
- Carbon sequestration, Machine learning modeling, Open porous media (OPM) flow, Petroleum engineering, Sensitivity analysis, Symbolic regression,
- Publikační typ
- časopisecké články MeSH
The paper is devoted to the analysis of a supersonic nozzle system effect in gas-cooled lances on the technological parameters of slag splashing in an oxygen converter. Simulation calculations were carried out, taking into account the parameters of nozzles used in the technological lines of converter steel plants in Ukraine and Brazil. The problems were solved in several stages. The simulation results of the first stage revealed the influence of different nozzle diameters dcr, dex and the inlet pressure before nozzle P0 on the nitrogen consumption of one nozzle Vн. Calculations also showed the influence of the critical dcr and output dex of the nozzle diameter and nitrogen flow through one nozzle Vн on the power of injected nitrogen N1 and the depth of penetration of the stream hx into the liquid slag. The second stage was dedicated to numerical simulation of the slag splashing process, including an array of results from the first stage. The thermodynamic and physical parameters were calculated using our own computer program, while 3D simulations were conducted using the ANSYS Fluent 2023 R2 program.
- Klíčová slova
- numerical modeling, optimization of process, recycling of waste material, supersonic jets, thermodynamic parameters of splashing,
- Publikační typ
- časopisecké články MeSH
The honey bee, Apis mellifera L., is one of the main pollinators worldwide. In a temperate climate, seasonality affects the life span, behavior, physiology, and immunity of honey bees. In consequence, it impacts their interaction with pathogens and parasites. In this study, we used Bayesian statistics and modeling to examine the immune response dynamics of summer and winter honey bee workers after injection with the heat-killed bacteria Serratia marcescens, an opportunistic honey bee pathogen. We investigated the humoral and cellular immune response at the transcriptional and functional levels using qPCR of selected immune genes, antimicrobial activity assay, and flow cytometric analysis of hemocyte concentration. Our data demonstrate increased antimicrobial activity at transcriptional and functional levels in summer and winter workers after injection, with a stronger immune response in winter bees. On the other hand, an increase in hemocyte concentration was observed only in the summer bee population. Our results indicate that the summer population mounts a cellular response when challenged with heat-killed S. marcescens, while winter honey bees predominantly rely on humoral immune reactions. We created a model describing the honey bee immune response dynamics to bacteria-derived components by applying Bayesian statistics to our data. This model can be employed in further research and facilitate the investigating of the honey bee immune system and its response to pathogens.
