Caffrey, Andrew J.Lafontaine, ScottDailey, JeffVarnum, Scott...
8页
查看更多>>摘要：Monoterpenes contribute to the characteristic aroma of several hop varieties and may occur as nonvolatile glycosides. Upon hydrolysis, the volatile terpenes are released from the glycoside precursors. Little is known, however, about the glycoside composition of hops. Seven pentose-hexose monoterpene alcohol glycosides from dried Humulus lupulus L. cv. Citra cones were isolated using high performance liquid chromatography separation and fractionation on a reverse phase phenyl-hexyl column. Further evaluation of each isolated fraction through HPLC qTOF MS with porous graphitic carbon (PGC) showed that the seven isolated monoterpenyl glycoside fractions could be further resolved into 20 isomers. Isolation on phenyl-hexyl followed by separation on PGC was needed to distinguish each isomer present. Additionally, the hop cones were screened for potential aroma glycosides. Using the PGC column combined with a database of over 900 potential glycosides, the identification of 21 additional monoterpene-polyol, norisoprenoid, volatile phenol, and aliphatic alcohol glycosides is reported.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
Geibel, ChristianKramer, MarkusLaemmerhofer, Michael
9页
查看更多>>摘要：The present work systematically investigates the chemical microheterogeneity as part of the optimization of a single-step surface bonding chemistry of 3-mercaptopropylsilatrane (MPS) on mesoporous silica gel in comparison to the state-of-the-art silane chemistry with 3-mercaptopropyltrimethoxysilane (MPTMS). MPS functionalization turns out to be a favourable chemistry for the further use in thiol-ene click reactions such as the immobilization of chiral selectors, herein tert -butylcarbamoylquinine (tBuCQN), for the synthesis of chiral stationary phases (CSPs). MPS has higher reactivity than MPTMS and prefers the formation of trifunctional siloxane bondings unlike MPTMS which favours difunctional siloxane bonds to silica, as investigated by solid-state cross-polarization/magic angle spinning (CP/MAS) NMR ( 29 Si and 13 C nuclei). Reaction conditions (ternary mixtures of methanol, water and toluene; with and without acid; prewetting of silica; HCl pretreatment of silica) were evaluated with the aim to find conditions which promote the formation of a horizontal siloxane polymer layer on top of the silica surface. Silanization reaction times could be reduced to 2 h. The 29 Si NMR signal corresponding to trifunctional siloxane bonding could be increased to 60% with no T1 signal that refers to monofunctional siloxane bonding in spite of water in the ternary reaction mixture. Furthermore, no significant disulfide bridges were formed in this approach, leading to high selector loadings. The thiol and selector coverage reached up to 4.6 and 1.4 mu mol/m 2 , respectively. With the preferred CSP, the enantioselectivity could be increased for a chiral probe (FMOC-Phe) and the mass transfer resistance (C-term) bisected compared to the corresponding CSP prepared from benchmark MPTMS-modified silica (2.54 vs 5.72 ms). It is demonstrated that the finetuning of the microstructure on the silica surface can have a significant influence on enantioselectivity and mass transfer kinetics of the resultant CSPs.
查看更多>>摘要：In this work, a simple and effective strategy for the determination of 12 active compounds of Atractylodes macrocephala Koidz. (AM) was proposed by using high performance liquid chromatography-diode array detection (HPLC-DAD) combined with alternating trilinear decomposition (ATLD) algorithm. Utilizing the "second-order advantage", three common problems in HPLC could be resolved, namely baseline drifts, peak overlaps, and unknown interferences. 12 compounds were rapidly eluted within 12.5 min, and the average spiked recoveries were 80.8-109.9%. The figures of merit reflected the feasibility of the proposed method. Compared with the results of the traditional univariate calibration method based on HPLC-UV technique, the proposed strategy further verified the reliability and simplicity of the mathematical separation. On this basis, partial least squares-discriminant analysis (PLS-DA) was applied to discriminate 113 AM samples from different geographical origins, and variable importance in projection (VIP) was used to further screen the main differential components that affect the regional division of AM. A series of results show that the AM samples from the three regions have obviously different clustering trends. Overall, the strategy is expected to provide a scientific basis for the modern research of medicinal materials, and it is also conducive to the clinical use and market supervision of AM.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A comprehensive chemical profiling of traditional Chinese medicine is the basic issue for further pharmacological research and quality assessment. To facilitate chemical identification and potential components discovery, the present study proposed an integrated identification strategy guided by a self-built component database constructed from literatures to carry out the global profiling of complex matrixes. Lanqin Oral Liquid was applied as example to validate the feasibility of this strategy. Based on LQL Component Database containing 710 compounds, modified MDF windows was established to extract the interested analogues, isoquinoline alkaloids, flavonoids and iridoid glycosides, according to their regular integral masses and mass defect. For compounds with characteristic substructures, such as quinic acids, crocins and some glycoside derivatives, the associated neutral losses and diagnostic fragment ions were collected to assist in profiling. Directly matching the m/z or formulas in database was proposed to components with limited regularity of accurate masses and substructures, like indole alkaloids, sesquiterpenes and some nucleosides. Eventually, 170 ions of 1038 precursor ions were identified or temporarily deduced, including 59 alkaloids, 36 flavonoids, 48 terpenoids, 24 organic acids and their derivatives, 2 oligosaccharides, and 1 lignans. Among them, 52 putative compounds were confirmed by chemical standards. The results indicated that the database-oriented identification strategy could locate potential components quickly and eliminate interfering ions, which have the potential for in-depth analysis of compounds.(c) 2022 Published by Elsevier B.V.
Pankajkumar-Patel, N.Peris-Garcia, E.Ruiz-Angel, M. J.Garcia-Alvarez-Coque, M. C....
10页
查看更多>>摘要：Aqueous microemulsions (MEs), where an oil coexists with water in the presence of the anionic surfactant sodium dodecyl sulphate (SDS), have been proposed as a solution to decrease the amount of organic solvent in the mobile phase needed in reversed-phase liquid chromatography (RPLC). However, the oil phase of a typical ME is volatile, toxic and flammable, and although it is added in a small amount, it would be desirable to avoid it from an environmental perspective. This is the reason for the proposal of Peng et al. (J. Chromatogr. A 1499 (2017) 132-139) to replace the oil in microemulsion liquid chromatography (MELC) by the apolar ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6C1IM][PF6]), to analyse neutral phenolic acids at acidic pH. Based on this report, an MELC procedure is here proposed for beta-adrenoceptor antagonists, which are basic compounds where the dominant species is cationic. To verify the formation of MEs containing SDS and IL, and elucidate the interactions between the cationic basic compounds with the SDS anion, and the cation and anion in the IL, an extensive study was carried out with several methylimidazolium ILs containing the cations [C2C1IM] +, [C4C1IM] +, or [C6C1IM] +, combined with the anions Cl -, BF4 -, or PF6 -, using 1-butanol as co-surfactant. The behaviour was com-pared with that observed in classical MELC with octane, micellar liquid chromatography with SDS and 1-propanol, and RPLC with mobile phases containing an IL and acetonitrile. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
查看更多>>摘要：An enzyme-assisted extraction and an ion pairing reversed phase chromatography (IP-RPC) coupled to inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) method were established for the simultaneous analysis of five selenium species in rice: selenious acid (SeIV), selenic acid (SeVI), selenocystine (SeCys2), methylselenocysteine (SeMeCys) and selenomethionine (SeMet). Optimal extraction efficiencies were obtained by using 15 mg protease XIV, water bath temperature of 45 ?, pH of 6.5 and incubation of six hours. The total extracted Se species account for 92.5-109.3 % of the total Se in rice. The instrumental limits of detection for five selenium species ranged from 0.04 to 0.12 ng Se g( -1). Spike recovery experiments performed on rice samples were in the range of 96.1-102.9 % for all analytes except for SeCys2 (66.1-77.1 %). A consistency of Se elemental response was observed among Se species analyzed in this study as the ratio of linear equation slope ranged from 1.020 to 1.036 (SeIV as reference) in rice matrix. The developed compound-independent calibration method was applied to detect Se species in eleven rice samples from China. Both selenium-enriched rice and regular rice were predominated with SeMet, accounting for & SIM;89.4 % of total selenium. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Sulfonamides (SAs) were widespread in animal-derived food at trace level, which could trigger hazards to human health. Herein, electric field enhanced thin-film microextraction (EE-TFME) was developed based on carbon cloth (CC) modified with metal-organic frameworks (MOFs) for extraction of SAs (sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethoxazole and sulfisoxazole), which were a series of polar analytes. MIL-101(Cr) was in situ synthesized on CC via hydrothermal reaction and then was used as positive electrode in EE-TFME for adsorption of SAs. Compared with traditional TFME, EE-TFME shortened extraction equilibrium time from 30 min to 15 min. Coupled with high-performance liquid chromatography (HPLC), the limits of detection (LODs) were 2.5-4.5 mu g/L, while the repeatability and intermediate precision was lower than 9.1%. Quantitative determination of SAs in extracts of animal-derived samples, such as honey, pork, chicken and milk, was achieved with recoveries from 81.7% to 114.2%. The developed MOF/CC-based EE-TFME has a great potential in rapid extraction of similar polar or ionic analytes from complex food matrices.(c) 2022 Elsevier B.V.All rights reserved.
查看更多>>摘要：Unsymmetrically disubstituted metallocene derivatives, characterized as the first sandwich structure, have found interest in asymmetrical synthesis and in medicinal chemistry as well. Besides, they present a particular case of chirality. Twenty original and six commercially available molecules presenting either i) a planar chirality or ii) an asymmetrical carbon containing group or iii) being symmetrically substituted were analyzed in supercritical fluid chromatography on eleven polysaccharide-based chiral stationary phases with carbon dioxide containing 30% of methanol or 2-propanol as a co-solvent mobile phase. A basic additive, either diethylamine, triethylamine or n-butylamine was also required at 1% to the co-solvent for elution. While some of the tested chiral stationary phases provided enantioseparation for the racemates, chlorinated cellulosic phases proved to be both highly retentive and highly enantioselective towards these particular species with the highest rate of success compared to their non-chlorinated counterparts. For instance, the resolution value was equal to 14.1 for one ferrocene derivative in one-hour analysis time on cellulose tris (3,5-dichlorophenylcarbamate) column with 30% 2propanol/1% n-butylamine while a single peak was observed under the same conditions on cellulose tris (3,5-dimethylphenylcarbamate) column. Experimental parameters were arbitrarily set at 150 bar outlet pressure, 40 & DEG;C temperature and 3 mL/min flow-rate. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have raised serious public health concerns because of their potential adverse effects in humans as revealed by toxicological and epidemiological research. However, routine monitoring of PFASs is still challenging due to their trace levels in various environmental and biological matrices. In this study, magnetic composite materials based on iron (II, III) oxide (Fe3O4) with surface functionalization by cucurbit(n)uril (CB(n)) (Fe3O4@CB(n)) ( n = 6, 7, 8), were prepared and evaluated as new adsorbents for the magnetic solid-phase extraction of nine PFASs in lake water, tap water and fish muscle samples. The Fe3O4@CB(n) was characterized to examine their surface morphologies, sizes magnetism and thermal stability. Featuring good aqueous solution dispersibility, the macrocyclic structure of Fe3O4@CB(n) was also endowed with strong host-guest interactions, allowing extraction and enrichment capability towards the PFASs in complex matrices. MSPE using Fe3O4@CB(7) combination with ultra-high performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry, gave satisfactory quantitative analytical performance with low limits of detection of 0.004-0.04 mu g L-1 and limits of quantification of 0.005-0.1 mu g L-1, linearities ranging from 0.01 to 10 mu g L-1 with high coefficients of determination (R-2 >= 0.993), and enrichment factors (15-76) for the nine target PFASs. The method proved to be effective for the enrichment and analysis of trace levels of PFASs in genuine environmental water and fish muscle samples, indicating that Fe3O4@CB(7) has promising applicability as an adsorbent for these contaminants. (c) 2022 Elsevier B.V. All rights reserved.
Medina, Deyber Arley VargasBurato, Juliana Soares da SilvaBorsatto, Joao Victor BasolliLancas, Fernando Mauro...
9页
查看更多>>摘要：A 25 mu m i.d x 1.2 m length PS-DVB porous layer open tubular column (PLOT) was prepared and assessed in the configuration of a nano liquid chromatography coupled to an electron ionization mass spectrometry system (OT-nanoLC-EI-Ms), via the direct insertion of the column outlet into the ionization source. The developed system's operational parameters were comprehensively studied, and the setup performance was investigated employing both unidimensional and column switching configurations. As a result, the OT-nanoLC-EI-MS system demonstrated competitive applicability in separating non-amenable ESI compounds, such as polyaromatic hydrocarbons (PAHs) and non-amenable GC compounds such as thermolabile pesticides. Furthermore, with excellent chromatographic performance, the PLOT columns can work under more compatible EI-detection conditions - such as the elution with 100% organic solvent. For example, PAHs retention factors ranged between 1.5 and 2.2 for 100% MeCN mobile phase, and more than 33,0 0 0 plates per meter for naphthalene at 50 nL/min flow rate. In analyzing thermolabile pesticides, the column switching PLOT-nanoLC-EI-MS system provided LODs of 25 mu g/L, demonstrating suitable intra e interday reproducibility (% RSD < 13%, n = 3), and possibilities the direct injection of raw samples with suitable robustness.(c) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier