查看更多>>摘要：Retention time prediction in high-performance liquid chromatography (HPLC) is the subject of many studies since it can improve the identification of unknown molecules in untargeted profiling using HPLC coupled with high-resolution mass spectrometry. Lots of approaches were developed for retention time prediction in liquid chromatography for a different number of molecules considering various molecular properties and machine learning algorithms. The recently built large retention time data set of standard compounds from the Metabolite and Chemical Entity Database (METLIN) allows researchers to create a model that can be used for retention time prediction of small molecules with wide varieties of structures and physicochemical properties. The ability to predict retention times using the largest data set was studied for different architectures of deep learning models that were trained on molecular fingerprints, and SMILES (string representation of a molecule) represented as one-hot matrices. The best result was achieved with a one-dimensional convolutional neural network (1D CNN) that uses SMILES as an input. The proposed model reached the mean absolute error and the median absolute error equal to 34.7 and 18.7 s, respectively, which outperformed the results previously obtained for this data set. The pre trained 1D CNN on the METLIN SMRT data set was transferred on five other data sets to evaluate the generalization ability. (c) 2021 Elsevier B.V. All rights reserved.
Schmitt, MatthiasEgorycheva, MarinaSeubert, Andreas
10页
查看更多>>摘要：Mixed-acidic cation-exchange (MCX) columns with both strongly (SCX) and weakly (WCX) acidic functional groups were developed for the separation of standard amino acids. The resins were prepared by carboxylation of highly crosslinked monodisperse poly(styrene-divinylbenzene) copolymer particles with performic acid and subsequent sulfonation with sulfuric acid. The degree of functionalization was varied independently for each processing step and controlled by measuring pH dependent retention of the obtained resins. A series of mixed-acidic resins with different SCX/WCX-ratios was chromatographically characterized by variation of formic acid and acetonitrile concentration in the aqueous eluent. The overall cation-exchange capacity was varied from 33 to 68 mu mol/mL. The comparison with two commercial columns (Metrohm Metrosep C6, WCX and Hamilton PRP X-200, SCX) revealed the additive character of the different functional group properties within MCX columns and a unique selectivity which can be adjusted by both eluent composition and SCX/WCX-ratio of the resin. The retention window between neutral and basic amino acids was altered by varying the amount of sulfonic acid groups attached to the polymer. Orthogonality plots demonstrated constant selectivity for neutral amino acids. Correlating the retention data with log P data demonstrated the influence of non-ionic hydrophobic and pi-pi-interactions for the separation of amino acids on PS/DVB-based cation-exchangers. An isocratic IC-ESI-MS method was developed to separate and quantitate 20 underivatized standard amino acids within 30 min. Limits of detection were between 4 and 64 nmol L-1 and a high linearity of calibration curves was obtained for all analytes. The method was validated by comparing a certified reference standard with external calibration data. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Nanoparticles are widely used in the medical field for diagnosis and therapy. In particular, the use of nanoparticles containing vaccines has spread rapidly; hence, ensuring nanoparticle safety and minimizing their side effects have become important concerns worldwide. In this study, we used three types (NH2, poly-Lys, and trimethylaminopropyl) of cationic modified silica monoliths with cylindrical structures, di-ameters of 4.2 mm, and heights of 1.5 mm. Doxil, an anticancer nanomedicine, and exosomes, as typical nanoparticles, were separated from model leaked drugs (e.g., doxorubicin and oligonucleotides) and pro-teins (e.g., albumin) coexisting in nanoparticle sample solutions using these monoliths. Each nanoparticle solution (200 mu L) was applied to each monolith followed by centrifugation at 9,100 g for 1 min. The ionic concentration of the elution solution was increased stepwise to determine the concentration required to elute the nanoparticles from each monolith by centrifugation. The NH2- and poly-Lys-modified monoliths separated and purified nanoparticles from leaked drugs or proteins coexisting in nanoparticle sample so-lutions. The nanoparticles were separated from other substances by changing the pH and concentration of the aqueous Tris buffer used as the eluent. Doxil was eluted with 500-1,000 mM Tris buffer (pH 8) when using the NH2-modified monolith, and with 200-1,000 mM Tris buffer (pH 6) when using the poly-Lys-modified monolith. Exosome was obtained using 1,000 mM Tris buffer (pH 8) and the NH2-modified monolith. The recovery efficiencies (ratio of nanoparticle content in the most abundant fraction to that in the sample solution before purification) of Doxil and exosome were 64% and 55%, respectively. Because this method can purify nanoparticles using only low-speed centrifugation for a few minutes, we expect it will be used to improve nanoparticle safety. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Polypropylene hollow fiber is a kind of ideal material for stir bar sorptive extraction (SBSE) which possesses the advantages of porous structure, large specific surface area, high mechanical strength, and good solvent resistance. In this work, a novel SBSE device using the polypropylene hollow fiber-based stir bar with the detachable dumbbell-shaped structure was designed and prepared. Covalent organic frameworkV (COF- V), which possesses porous structure, sphere shape with large specific surface area, was synthesized at room temperature and grown on polypropylene hollow fiber by polydopamine modification method. Compared with previous studies which used etched poly(ether ether ketone) as supporting material, polypropylene hollow fiber omitted the complicated, difficult and dangerous pretreatment process with high concentrated sulfuric acid. The immobilization of COF-V on the polypropylene hollow fiber significantly endows them with multiple interaction abilities including hydrophobic interaction and pi- pi interaction. The stir bar showed good performance and stability for the extraction of four benzophenones including BP-1, BP-6, BP-3 and Ph-BP. By coupling with HPLC-UV, the COF-V@polypropylene hollow fiber based SBSE method showed wide linear range (0.1-200 ng/mL), excellent linearity (R 2 >= 0.9979), high sensitivity (LODs in the range of 0.02-0.03 ng/mL), and good repeatability (RSD <= 5.21%). This method was successfully applied to the analysis of benzophenones in soil and sunscreen samples. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：Liquid chromatography coupled to mass spectrometry (LC-MS) is a powerful technique commonly used for pesticide residue analysis in agri-food matrices. Despite the fact it has several advantages, one of the main problems is the transferability of the data from one analytical equipment to another for identification and quantitation purposes. In this study, instrument-agnostizing methodology was used to set standard retention scores (SRSs), which was utilized as a parameter for the identification of 74 targeted compounds when different instruments are used. The SRS variation was lower than 5% for most of the compounds included in this study, which is much lower than those obtained when retention times were compared, correcting the elution shift between LC instruments. Additionally, this methodology was also tested for quantitation purposes, and normalized areas were used as analytical responses, allowing for the determination of the concentrations of the targeted compounds in samples injected in one equipment using the analytical responses of standards from another one. The applicability of this approach was tested at two concentrations, 0.06 and 0.15 mg/kg, and less than 10 out of 74 compounds were quantified with an error higher than 40% at 0.06 mg/kg and 0.15 mg/kg, showing that this methodology could be useful to minimize differences between LC-MS systems. (c) 2021 Elsevier B.V. All rights reserved.
Herman, Chase E.Xu, XuankuoTraylor, Steven J.Ghose, Sanchayita...
10页
查看更多>>摘要：Flow-through ion-exchange chromatography is frequently used in polishing biotherapeutics, but the factors that contribute to impurity persistence are incompletely understood. A large number of dilute impurities may be encountered that exhibit physicochemical diversity, making the flow-through separation performance highly sensitive to process conditions. The analysis presented in this work develops two novel correlations that offer transferable insights into the chromatographic behavior of weakly adsorbing impurities. The first, based on column simulations and validated experimentally, delineates the relative contributions of thermodynamic, transport, and geometric properties in dictating the initial breakthrough volumes of dilute species. The Graetz number for mass transfer was found to generalize the transport contributions, enabling estimation of a threshold in the equilibrium constant below which impurity persistence is expected. Impurity adsorption equilibria are needed to use this correlation, but such data are not typically available. The second relationship presented in this work may be used to reduce the experimental burden of estimating adsorption equilibria as a function of ionic strength. A correlation between stoichiometric displacement model parameters was found by consolidating isocratic retention data for over 200 protein-pH-resin combinations from the extant literature. Coupled with Yamamoto's analysis of linear gradient elution data, this correlation may be used to estimate retentivity approximately from a single experimental measurement, which could prove useful in predicting host-cell protein chromatographic behavior . (c) 2021 Elsevier B.V. All rights reserved.
Schuller, MariaTran, Kim Tu ThiOiestad, Elisabeth LeerePedersen-Bjergaard, Stig...
8页
查看更多>>摘要：The present paper defines the optimal extraction window (OEW) for three-phase membrane-based liquidphase microextraction (MP-LPME) in terms of analyte polarity (log P), and anchors this to existing theories for equilibrium partitioning and kinetics. Using deep eutectic solvents (DES) as supported liquid membranes (SLM), we investigated how the OEW was affected by ionic-, hydrogen bond and pi- pi interactions between the SLM and analyte. Eleven basic model analytes in the range -0.4 < log P < 5.0 were extracted by MB-LPME in a 96-well format. Extraction was performed from 250 mu L standard solution in 25 mM phosphate buffer (pH 7.0) into 50 mu L of 10 mM HCl acceptor solution (pH 2.0) with mixtures of coumarin, camphor, DL-menthol, and thymol, with and without the ionic carrier di(2-ethylhexyl) phosphate (DEHP), as the SLM. The OEW with pure DES was in the range 2 < log P < 5, and low SLM aromaticity was favorable for the extraction of non-polar analytes. Here, extraction recoveries up to 98% were obtained. Upon addition of DEHP to the SLMs, the OEW shifted to the range -0.5 < log P < 2, and a combination of 5% DEHP and moderate aromaticity resulted in extraction recoveries up to 80% for the polar analytes. Extraction with ionic carrier was inefficient for the non-polar analytes, due to excessive trapping in the SLM. The results from our study show that LPME performs optimally in a relatively narrow log P-window of approximate to 2-3 units and that the OEW is primarily affected by ionic carrier and aromaticity. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
Niu, Xi-ZhiAbrell, LeifSierra-Alvarez, ReyesField, Jim A....
7页
查看更多>>摘要：Ultra-hydrophilic perand polyfluorinated sulfonates (PFSA) are increasingly scrutinized in recent years due to their ubiquitous occurrence, persistence, and aqueous mobility in the environment, yet analysis remains a challenge. This study developed methods for the analysis of trifluoromethanesulfonate, perfluorobutanesulfonate, 10-camphorsulfonate, and a di-fluorinated sulfonate utilizing mixed-mode liquid chromatography, where all analytes were adequately retained and separated. Chromatography and electrospray ionization parameters were optimized; instrumental limits of quantification for the anionic target analytes were in the range of 4.3 - 16.1 ng L-1. Solid phase extraction (SPE) methods were developed using Oasis WAX cartridges; SPE recoveries for the analytes ranged from 86% to 125%. Salinity and total organic carbon both impaired the SPE performance to different extents, depending on the respective analyte. Utilizing widely accessible instrumentation and materials, this is a single method to simultaneously analyze conceivably the most hydrophilic PFAS chemical, i.e., trifluoromethanesulfonate, and moderately hydrophobic PFSAs. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：The pseudotargeted metabolomics based on gas chromatography-mass spectrometry (GC-MS) has the advantage of filtering out artifacts originating from sample treatment and accurately quantifying underlying compounds in the analyzed samples. However, this technique faces the problem of selecting high-quality selective ions for performing selected ion monitoring (SIM) on instruments. In this work, we proposed AntDAS-SIMOpt, an automatic untargeted strategy for SIM ion optimization that was accomplished on the basis of an experimental design combined with advanced chemometric algorithms. First, a group of diluted quality control samples was used to screen underlying compounds in samples automatically. Ions in each of the resolved mass spectrum were then evaluated by using the developed algorithms to identify the SIM ion. A Matlab graphical user interface (GUI) was designed to facilitate routine analysis, which can be obtained from http://www.pmdb.org.cn/antdassimopt . The performance of the developed strategy was comprehensively investigated by using standard and complex plant datasets. Results indicated that AntDAS-SIMOpt may be useful for GC-MS-based metabolomics. (c) 2022 Elsevier B.V. All rights reserved.
Soto, C.Ponce-Rodriguez, H. D.Verdu-Andres, J.Herraez-Hernandez, R....
10页
查看更多>>摘要：In this study three miniaturized liquid chromatography (LC) instruments have been evaluated and compared for the analysis of caffeine in dietary supplements, namely a benchtop capillary LC (capLC) system, a benchtop nano LC (nanoLC)system and a portable LC system. Commercial products derived from different sources of caffeine have been analyzed. Under optimized conditions, the methods based on benchtop systems were superior in terms of sensitivity. The limits of detection (LODs) found with the capLC and nanoLC systems were 0.01 and 0.003 mu g mL(-1), respectively, whereas the LOD obtained with the portable LC instrument was of 1 mu g mL(-1). The portable LC-based method was superior in terms of simplicity and throughput (total analysis time < 15 min). On the basis of the results obtained, a new method for the rapid measurement of caffeine in dietary supplements by portable miniaturized LC is presented. This method provided good linearity within the 1-20 mu g mL(-1) interval, and it allowed the quantification of caffeine even in products derived from decaffeinated green coffee extracts. The contents of caffeine found with the proposed portable LC method in the real samples analyzed ranged from 1.38 to 7 mg per gram of product, which were values statistically equivalent to those found with the benchtop capLC and nanoLC methods, being the precision, expressed as relative standard deviation (RDS), of 2 -14% (n = 3). The proposed portable LC based method can be used as a simple and rapid alternative to estimate the quality, effectiveness and safety of dietary supplements, regarding their caffeine content. (C) 2021 Elsevier B.V. All rights reserved.
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