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1.
J Chromatogr A ; 1627: 461404, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823109

RESUMO

Liamocin biosurfactants and structurally related exophilins secreted by the Aureobasidium pullulans (A. pullulans) strain NRRL62031 were firstly analyzed by hyphenation of high-performance liquid chromatography (HPLC) with high-resolution mass spectrometry (HRMS). Ten different analytes were detected and identified by their accurate masses and divided into subclasses according to their different head groups: three liamocins with arabitol as head group, three mannitol liamocins, and four exophilins. A baseline separation of congeners within the subclasses was achieved by reversed phase HPLC on a C18 stationary phase, whereas an overlap of subclasses occurred. The structures were simultaneously confirmed by online tandem mass spectrometry (MS/MS) experiments in positive and negative ionization mode. The assigned polyol head groups and thus the feasibility of this method were confirmed by gas chromatography (GC)-MS data obtained after hydrolysis and derivatization of the liamocins. Based on the varying structural characteristics of liamocins, e.g. the polyol head group (or even none for exophilins) and the degree of acetylation, different detector response in LC-MS was expected, impairing relative quantification of congeners. Therefore, a complementary quantification method was developed using HPLC coupled to charged-aerosol detection (CAD), which allows the determination of the amount of the individual liamocin species without authentic liamocin standards. Hence, the here presented hyphenated techniques facilitate comprehensive analysis of liamocin biosurfactants.


Assuntos
Aerossóis/análise , Cromatografia de Fase Reversa/métodos , Manitol/análise , Tensoativos/análise , Espectrometria de Massas em Tandem , Ascomicetos/química , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Manitol/química , Álcoois Açúcares/análise , Álcoois Açúcares/química
2.
J Chromatogr A ; 1627: 461421, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823116

RESUMO

Herein we present an efficient, column-switching method that relies on a custom-made T-union passive diffusion micromixer to assist water dilution and promote trap solute focusing of a high sample volume dissolved in pure organic solvent using a 0.075 mm i.d. nano-LC column. This method allows injecting 20 µL (or higher) of sample volume, speeding up the analysis time, with a 400-fold increase of the limits of quantitation for selected compounds. Five pesticides in different media were used as model compounds, and the analyses were carried out with a triple quadrupole mass spectrometer equipped with a Liquid Electron Ionization (LEI) LC-MS interface working in multiple reaction monitoring (MRM) mode. The system microfluidics were investigated using COMSOL modeling software. Robustness of the entire system was evaluated using a post-extraction addition soil extracts with limits of detection values spanning from 0.10 to 0.45 µg/L. Reproducible results in terms of peak area, peak shape, and retention times were achieved in soil matrix. Repeatability test on peak area variations were lower than 10%.


Assuntos
Cromatografia de Fase Reversa/métodos , Elétrons , Microfluídica/métodos , Nanopartículas/química , Espectrometria de Massas em Tandem/métodos , Água/química , Acetonitrilos/química , Difusão , Limite de Detecção , Praguicidas/análise , Reprodutibilidade dos Testes , Solventes/química
3.
J Chromatogr A ; 1627: 461430, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823119

RESUMO

There is a huge, still increasing market for synthetic and therapeutic peptides. Their quality control is commonly based on a generic reversed-phase liquid chromatography (RPLC) method with C18 stationary phase and acetonitrile gradient with 0.1% trifluoroacetic acid in the mobile phase. It performs exceptionally well for a wide variety of impurities, yet structurally closely related impurities with similar sequences, not resolved in preparative RPLC, may easily coelute in the corresponding QC run as well. To address this problem an advanced generic 2D-LC impurity profiling method was developed in this work. It employs a selective comprehensive (high resolution sampling) RP×RP 2D-LC separation using a 100×2.1 mm ID column with the common acidic generic gradient in the first dimension, while RPLC under basic pH on a short 30×3 mm ID column is used in the second dimension. Recording data with a UV detector at 215 nm after 1D separation provides the common generic 1D chromatogram. However, after the 2D separation a flow splitter enabled recording of the signals of complementary detectors comprising a diode array detector (DAD) in-line with a charged aerosol detector (CAD) and a quadrupole-time-of-flight (QTOF) mass spectrometer (MS) with an electrospray ionization (ESI) source. Generic conditions of this 2D-LC method have been established through optimization of 2D stationary and mobile phase considering different pH values and buffer concentrations. The orthogonal separation principle has been documented by a number of therapeutic peptides including Exenatide, Octreotide, Cyclosporine A and Oxytocin as well as some other proprietary synthetic peptides. The information density can be further enhanced by using the QTOF-MS detector by data independent acquisition with SWATH. Through this sequential window acquisition of all theoretical fragment ion mass spectra it became possible to collect MS/MS data comprehensively in the high-resolution sampling window, thus enabling the extraction of 2D-EICs from fragment ions and the generation of 2D-contour plots of all product ions. Using Oxytocin as an example for an important therapeutic peptide, the ability of this advanced generic sRP-UV×RP-DAD-CAD-ESI-QTOF-MS/MS method with SWATH for peptide quality control is discussed.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Peptídeos/análise , Acetonitrilos/química , Tampões (Química) , Concentração de Íons de Hidrogênio , Ocitocina/análise , Controle de Qualidade , Solventes/química , Espectrometria de Massas em Tandem
4.
J Chromatogr A ; 1626: 461353, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797833

RESUMO

This paper reports the development of an LC-ESI-MS2 method for the sensitive determination of hydroxylated polychlorinated biphenyls (OH-PCBs) in human serum samples. Congener-specific separation was achieved by using a polar-embedded stationary phase, previously optimized for the working group, which provided better separation of isobaric compounds than the common octadecylsilane phases. MS fragmentation patterns and energies showed differences among OH-PCB congeners, mainly depending on the position of OH-group and the number of chlorine atoms in the molecule, although the most intense transitions were always those corresponding to the neutral loss of an HCl group from the quasi-molecular ion cluster. The method allowed the determination of OH-PCBs with good linearity (dynamic linear range of four orders of magnitude with R2 higher than 0.995) and precision (relative standard deviations of absolute areas lower than 10%), and with better sensitivity than other similar methods previously described in the literature. Matrix effect has been evaluated and reduced to less than 10% by the addition of isotopically labeled standards and a 10-fold dilution of the final sample extract. The low iLODs provided by the developed method (from 1.2 to 5.4 fg µL-1 for all the OH-PCBs studied, except 4'-OHCB108, whose iLOD was 61 fg µL-1) allows dilution without losses of detected peaks. Finally, the applicability of the method has been demonstrated by analyzing human serum samples belonging to an interlaboratory exercise.


Assuntos
Cromatografia Líquida/métodos , Cromatografia de Fase Reversa/métodos , Bifenilos Policlorados/análise , Espectrometria de Massas em Tandem/métodos , Humanos , Hidroxilação , Bifenilos Policlorados/sangue , Bifenilos Policlorados/química , Espectrometria de Massas por Ionização por Electrospray
5.
J Chromatogr A ; 1626: 461308, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797813

RESUMO

The Wayne State University (WSU) experimental descriptor database is utilized to bench mark the current capability of the solvation parameter model for use as a quantitative structure-retention relationship tool for estimating retention in gas and reversed-phase liquid chromatography. The prediction error for the retention factors of varied compounds on six open-tubular columns for gas chromatography (Rtx-5 SIL MS, DB-35 ms, RtxCLPesticides, HP-88, HP-INNOWAX and SLB-IL76) and three packed columns for reversed-phase liquid chromatography (SunFire C18, XBridge Shield RP18, and XBridge Phenyl) is used to establish expectations related to current practices. Each column data set was divided into a training set for calibration and a test set for validation employing a roughly 1 to 2 split, such that each test set contained about 40 to 80 varied compounds. The average absolute error for the prediction of retention factors by gas chromatography varied from about 0.1 to 0.4 on the retention factor scale with the larger error typical of stationary phases ranked as the most polar (or cohesive). For reversed-phase liquid chromatography the average error for the prediction of retention factors was 0.3 to 0.5 and generally larger than for gas chromatography. Statistical filters where utilized to identify a group of polycyclic aromatic compounds without hydrogen-bonding functional groups with a larger prediction error on the SunFire C18 column than for other compounds of smaller size, flexible structure or containing hydrogen-bonding functional groups. The heterogeneity of the retention mechanism is speculated to be the main contribution to the prediction error for both gas and liquid chromatography using the solvation parameter model.


Assuntos
Cromatografia Gasosa/métodos , Cromatografia de Fase Reversa/métodos , Ligação de Hidrogênio , Cinética , Solventes/química
6.
J Chromatogr A ; 1625: 461281, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709332

RESUMO

Polysaccharide-based chiral stationary phases (CSPs) are the most used chiral selectors in HPLC. These CSPs can be used in normal, polar organic and aqueous-organic mobile phases. However, normal and polar organic mobile phases are not adequate for chiral separation of polar compounds, for the analysis of aqueous samples and for MS detection. In these situations, reversed phase conditions, without the usual non-volatile additives incompatible with MS detection, are preferable. Moreover, in most of the reported chiral chromatographic methods, retention is too large for routine work. In this paper, the chiral separation of 53 structurally unrelated compounds is studied using three commercial amylose-based CSPs -coated amylose tris(3,5-dimethylphenylcarbamate) (Am1), coated amylose tris(5-chloro-2-methylphenylcarbamate) (Am2), and immobilised amylose tris(3-chloro-5-methylphenylcarbamate) (Am3)-. Chiral separations are carried out using acetonitrile/ammonium bicarbonate (pH = 8.0) mixtures, reversed mobile phases compatible with MS detection. To provide realistic conditions for routine analysis, maximum retention factors are set to 15. Retention and enantioresolution behaviour of compounds in those CSPs are compared. On the other hand, to compare and describe the resolution ability of these CSPs, 58 structural variables of the compounds are tested to model for the first time a categorical enantioresolution (CRs) for Am1 and Am3 CSPs. Discriminant partial least squares, for one response categorical variable (DPLS1) is used for feature selection, modelling. The final DPLS1 models showed good descriptive ability.


Assuntos
Amilose/química , Cromatografia de Fase Reversa/métodos , Espectrometria de Massas/métodos , Modelos Químicos , Cromatografia Líquida de Alta Pressão , Análise dos Mínimos Quadrados , Análise de Regressão , Estereoisomerismo
7.
J Chromatogr A ; 1625: 461285, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709335

RESUMO

An experimental methodology for the determination of the obstruction factor in the expression for mesopore diffusion in Zorbax Eclipse Plus C18 reversed-phase particles is proposed. The method uses peak parking experiments conducted on particles that were previously stripped of their stationary phase by flushing the column with trifluoroacetic acid at a temperature of 60°C. Further using pure organic solvents as the mobile phase, any potential retention or surface diffusion effect is omitted. To avoid interference between the parked peaks and baseline disturbances typically occurring when switching on and off the flow, peak parking experiments were carried out in a set-up wherein two identical columns were used in parallel. This set-up allowed to maintain the flow through the detector at all times, by redirecting the flow from one column to the other during the peak parking experiments. Several tracer molecules (ionic and deuterated tracers) were compared and it was found that the use of deuterated molecules provides the best possible coverage of the accessible space of the mesopore volume. Interpreting the peak parking responses obtained with these tracers with a model based on the effective medium theory (EMT) subsequently provided an estimate of the value of the mesopore diffusion obstruction factor γmp. Taking the well-established pore hindrance factor F(λ) correction into account, the obtained experimental γmp-values are more in agreement with the tortuous and constricted diffusion paths one can expect in the void space within a structure resembling a monolithic skeleton with tetrahedral connectivity rather than in the void space formed by a packing of nanospheres. This is also more in line with the measured internal porosity values lying around εpz=0.5, whereas a packing of nanospheres would rather correspond to an Îµpz of 0.4. As such, the presented protocol provides a means to infer the internal mesopore structure of reversed-phase particles.


Assuntos
Cromatografia de Fase Reversa/métodos , Modelos Químicos , Cromatografia Líquida , Difusão , Peso Molecular , Porosidade , Solventes/química
8.
J Chromatogr A ; 1625: 461334, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709359

RESUMO

A comprehensive study on the chiral separation of bupivacaine, mepivacaine, prilocaine and propanocaine with eight commercial polysaccharide-based chiral stationary phases (CSPs) in reversed phase conditions compatible with MS detection is performed. Methanol and acetonitrile are used as organic modifiers. Retention and resolution values obtained for each compound in the different CSPs and mobile phases are compared. The polysaccharide-based CSPs tested present different enantioselectivity towards the analytes. From the results, the experimental conditions for determining the enantiomers of bupivacaine, mepivacaine, prilocaine and propanocaine in saline aqueous samples using MS detection are used, for the first time, to perform an enantioselective biodegradability study.


Assuntos
Anestésicos Locais/isolamento & purificação , Cromatografia de Fase Reversa/métodos , Polissacarídeos/química , Acetonitrilos/química , Biodegradação Ambiental , Cromatografia Líquida de Alta Pressão , Metanol/química , Peso Molecular , Estereoisomerismo , Água/química
9.
J Chromatogr A ; 1625: 461338, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709362

RESUMO

Until today, ion-pair reversed-phase chromatography is still the dominating method for analytical characterization of synthetic oligonucleotides. Its hyphenation with mass spectrometry, however, has some drawbacks such as ion-suppression in electrospray ionization. To overcome this problem, we present in this work a multiple heart-cutting (MHC) two-dimensional liquid chromatography (2D-LC) method with ultra-violet (UV) and electrospray ionization (ESI) mass spectrometry (MS) detection. A reversed-phase/weak anion-exchange (RP/WAX) stationary phase in the first dimension (1D) provides the selectivity for separation of structurally closely related oligonucleotide sequences and deletions (shortmers), respectively, using a mixed pH/triethylammonium phosphate buffer gradient at constant organic modifier content. Heart cuts of the oligonucleotide peaks are transferred to the second dimension (2D) via a multiple heart-cutting valve which is equipped with two loop decks. The 2D RP column is used for desalting via a diverter valve. Active solvent modulation enables to refocus the oligonucleotide peak into a sharp zone by 2D RP entirely free of non-volatile buffer components and ion-pair agents. Oligonucleotides can thus be sensitively detected by ESI-QTOF-MS under MS-compatible conditions.


Assuntos
Cromatografia de Fase Reversa/métodos , Oligonucleotídeos/química , Oligonucleotídeos/isolamento & purificação , Espectrometria de Massas por Ionização por Electrospray/métodos , Ânions , Cromatografia por Troca Iônica , Oligonucleotídeos/análise , Polímeros/química
10.
Food Chem ; 332: 127394, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32610259

RESUMO

In this study, we present the preparation of a new reverse-phase/phenylboronic-acid (RP/PBA)-type mixed-mode magnetic solid-phase extraction (MSPE) adsorbent for use in the cleanup of amatoxin- and phallotoxin-containing samples intended for ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. Further, the RP/PBA magnetic microspheres have phenyl and phenylboronic acid groups on their surfaces that selectively adsorb amatoxins and phallotoxins through hydrophobic, π-π, and boronate affinity, significantly reducing matrix effects in UPLC-MS/MS analysis. After systematic optimization, all the standard calibration curves expressed satisfactory linearity (r > 0.9930), limits of detection (0.3 µg/kg), and recovery (97.6%-114.2%). Compared with other reported methods, this method also has the advantages of simple, fast, and efficient operation using relatively small amounts of the MSPE adsorbent. Furthermore, the method was successfully applied in a poisoning incident caused by Lepiota brunneoincarnata Chodat & C. Martín ingestion.


Assuntos
Amanitinas/análise , Ácidos Borônicos/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Imãs/química , Espectrometria de Massas em Tandem/métodos , Adsorção , Amanitinas/isolamento & purificação , Limite de Detecção , Microesferas , Extração em Fase Sólida
11.
J Chromatogr A ; 1623: 461159, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505275

RESUMO

In the last decade, 3D-printing has emerged as a promising enabling technology in the field of analytical chemistry. Fused-deposition modelling (FDM) is a popular, low-cost and widely accessible technique. In this study, RPLC separations are achieved by in-situ fabrication of porous polymer monoliths, directly within the 3D-printed channels. Thermal polymerization was employed for the fabrication of monolithic columns in optically non-transparent column housings, 3D-printed using two different polypropylene materials. Both acrylate-based and polystyrene-based monoliths were created. Two approaches were used for monolith fabrication, viz. (i) in standard polypropylene (PP) a two-step process was developed, with a radical initiated wall-modification step 2,2'-azobis(2-methylpropionitrile) (AIBN) as the initiator, followed by a polymerization step to generate the monolith; (ii) for glass-reinforced PP (GPP) a silanization step or wall modification preceded the polymerization reaction. The success of wall attachment and the morphology of the monoliths were studied using scanning electron microscopy (SEM), and the permeability of the columns was studied in flow experiments. In both types of housings polystyrene-divinylbenzene (PS-DVB) monoliths were successfully fabricated with good wall attachment. Within the glass-reinforced polypropylene (GPP) printed housing, SEM pictures showed a radially homogenous monolithic structure. The feasibility of performing liquid-chromatographic separations in 3D-printed channels was demonstrated.


Assuntos
Cromatografia de Fase Reversa/métodos , Polipropilenos/química , Impressão Tridimensional , Microscopia Eletrônica de Varredura , Polimerização , Polímeros/química , Poliestirenos/química , Porosidade , Compostos de Vinila/química
12.
J Chromatogr A ; 1623: 461211, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505295

RESUMO

This is the second of a two-part study in which we explore the concept of batch chromatography with recycle lag, concluding with the design, construction, and experimental validation of a prototype-an eluate recycling device (ERD)-that embodies the physical realization of this concept. The ERD implements an approximate "first in, first out" method of organizing and manipulating the to-be-recycled fractions of eluate collected from the chromatography column, where the oldest (first) amount fluid, or 'head' of the fraction, is the first to exit and be recycled back to the column. Moreover, the apparatus is simple to set up in particular in view of large-scale applications. Here we detail the construction of the ERD and assembly of a setup to interconnect the ERD and a chromatography column. Through the coordinated operation of two-way valves and two-position six-port switching valves it is possible to implement a diverse set of configurations or operating modes interconnecting the chromatography column and the ERD. The setup is validated experimentally with success using the separation of a nucleoside mixture by reversed phase chromatography as a model problem. It is also shown that by redesigning the fluid distributor using 3D printing technology the ERD performance can be improved.


Assuntos
Cromatografia de Fase Reversa/métodos , Reciclagem , Simulação por Computador , Hidrodinâmica , Nucleosídeos/análise , Impressão Tridimensional , Reprodutibilidade dos Testes , Rodaminas/química , Fatores de Tempo
13.
J Food Sci ; 85(5): 1418-1426, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32304227

RESUMO

As a major product of linoleic acid-rich oils, 2,4-decadienal has unique reactivity that may be potentially toxic to human body. In this study, a reliable reversed-phase liquid chromatography method for the determination of carbonyls was developed, and 2,4-decadienal as the target aldehyde was validated. Furthermore, the possibility of 2,4-decadienal as a lipid oxidation marker was evaluated. The optimal sample pretreatment method was extraction by 2 mL of acetonitrile three times, followed by derivatization at 40 °C for 30 min. The method was linear, sensitive, and accurate with detection and quantification limits of 15 and 50 nmol/L, respectively, and had good average recoveries for 2,4-decadienal in oil samples. In tested edible oils, during heating at 180 °C, the level of 2,4-decadienal rose faster than other aldehydes, including one of the characteristic aldehydes, hexanal. Moreover, good linear relationships between the 2,4-decadienal content and other oxidation indices (R2 = 0.858 to 0.984 for the anisidine value; R2 = 0.876 to 0.986 for the total oxidation value) were observed in sunflower and corn oils under 8 hr heating at three temperatures (120, 150, and 180 °C), indicating that 2,4-decadienal can predict the oxidation of oil. PRACTICAL APPLICATION: 2,4-Decadienal is a toxic aldehyde produced by the oxidation of linoleic acid-rich oils, which is closely related to human health. This work is the first to demonstrate that 2,4-decadienal can be used as an alternative oxidation indicator for linoleic acid-rich oils and is of great significance for the quality control of edible oil in the food industry.


Assuntos
Aldeídos/análise , Óleos Vegetais/química , Cromatografia de Fase Reversa/métodos , Culinária , Temperatura Alta , Oxirredução
14.
J Chromatogr A ; 1620: 461023, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32173021

RESUMO

Phase ratio Φ for an high performance liquid chromatography (HPLC) column is a parameter defined as the ratio between the volume of the stationary phase Vs and the void volume of the column Vm. Together with the equilibrium constant K of the separation process, phase ratio is part of the retention factor k (k = KΦ). Although a considerable number of studies have been dedicated to the evaluation of Vs and Vm with the goal of obtaining the value for Φ, there are still debatable results regarding the true value of Φ, which for a column with a specific stationary phase may vary with the composition of the mobile phase. One route for the evaluation of the value of Φ uses the measurements of retention factors k on a specific column and mobile phase for two or more hydrocarbons for which the octanol/water partition coefficients log Kow are known. This procedure has been applied in the present study for the evaluation of Φ for three commercially available C18 columns and two mobile phase compositions water/acetonitrile, in the temperature range 20 °C to 50 °C. It was found that phase ratio does change depending on the temperature, its "effective value" decreasing as the temperature increases which is in accordance with the decrease of retention times in reversed phase HPLC when the temperature increases. Besides other factors that may affect the correct calculation of thermodynamic functions, the change of phase ratio with temperature has implications regarding the possibility to calculate the enthalpy and entropy values from van't Hoff plots of the variation of log k as a function of 1/T, even when the retention process is dominated by unique hydrophobic type interactions.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Temperatura , Entropia , Interações Hidrofóbicas e Hidrofílicas , Solventes/química , Água/química
15.
J Chromatogr A ; 1620: 461010, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32173025

RESUMO

In this paper, adsorption mechanism of triterpenoid saponins in reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) was proposed based on the study of the retention behavior of mogroside V as test substance. The change of peak shape of mogroside V and its influencing factors was first investigated. As the increase of sample loading, a tailing peak of mogroside V was observed in MeOHH2O of both two modes. It was the fronting peak in ACNH2O of HILIC while there was a transition from fronting peak to tailing peak in ACNH2O of RPLC that was largely affected by column temperature and ACN concentration. The adsorption isotherm of mogroside V in ACNH2O of RPLC was fitted by Moreau model, where a monolayer adsorption with large inter-molecular interaction was formed on the C18 surface. While in ACNH2O of HILIC, the adsorption of mogroside V was in accordance with BET model, showing multilayer adsorption behavior. In MeOHH2O of both HILIC and RPLC, there was always monolayer adsorption, which was fitted by Langmuir model. At last, by choosing the suitable chromatographic mode, controlling the key factors such as the solvent concentration and column temperature, and predicting the broadening trend of peak, three methods were screened out, namely, C18 column with 22% ACN (30 °C), Click XIon column with 90% MeOH or 70% ACN, to get mogroside V of purity greater than 98% from Siraitia grosvenorii extract. Among them, the RPLC method of 22% ACN that showed the highest loading sample per hour (1.92%) and the lowest solvent consumption emerged as the best approach.


Assuntos
Cromatografia Líquida/métodos , Cromatografia de Fase Reversa/métodos , Interações Hidrofóbicas e Hidrofílicas , Saponinas/isolamento & purificação , Triterpenos/isolamento & purificação , Adsorção , Saponinas/química , Solventes , Temperatura , Triterpenos/química
16.
J Chromatogr A ; 1621: 461040, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32204883

RESUMO

We offer a concept for the simultaneous determination of QuEChERS amenable and highly polar pesticides using two-dimensional liquid chromatography high resolution mass spectrometry with electrospray ionization (ESI) and polarity switching. First results proved feasibility to determine glyphosate, AMPA, ethephon, glufosinate, MPPA, fosetyl-Al, N-acetyl-glufosinate, N-acetyl-glyphosate and N-acetyl-AMPA including fragments, next to 325 QuEChERS amenable pesticides. We plan to investigate an efficient extraction procedure by either diluting with water or acetonitrile extraction in mini scale without the need for additional clean-up steps. After completion of all experiments, the method will be validated and expanded for further pesticides and organic contaminants. Therefore, we present a concept for a Two-dimensional HILIC Reversed phase Easily Extracted Pesticides and Polar Pesticides (THREEP or 3P(+)) multi-residue method.


Assuntos
Cromatografia de Fase Reversa/métodos , Resíduos de Praguicidas/análise , Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Resíduos de Praguicidas/isolamento & purificação , Espectrometria de Massas por Ionização por Electrospray
17.
J Agric Food Chem ; 68(10): 3121-3131, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32053364

RESUMO

A new method to simultaneously analyze various glucosinolates (GSLs) and isothiocyanates (ITCs) by reversed-phase ultra-high-performance liquid chromatography-electron spray ionization-tandem mass spectrometry has been developed and validated for 14 GSLs and 15 ITCs. It involved derivatization of ITCs with N-acetyl-l-cysteine (NAC). The limits of detection were 0.4-1.6 µM for GSLs and 0.9-2.6 µM for NAC-ITCs. The analysis of Sinapis alba, Brassica napus, and Brassica juncea extracts spiked with 14 GSLs and 15 ITCs indicated that the method generally had good intraday (≤10% RSD) and interday precisions (≤16% RSD). Recovery of the method was unaffected by the extracts and within 71-110% for GSLs and 66-122% for NAC-ITCs. The method was able to monitor the enzymatic hydrolysis of standard GSLs to ITCs in mixtures. Furthermore, GSLs and ITCs were simultaneously determined in Brassicaceae plant extracts before and after myrosinase treatment. This method can be applied to further investigate the enzymatic conversion of GSLs to ITCs in complex mixtures.


Assuntos
Brassicaceae/química , Cromatografia Líquida de Alta Pressão/métodos , Glucosinolatos/química , Isotiocianatos/química , Extratos Vegetais/química , Sinapis/química , Espectrometria de Massas em Tandem/métodos , Cromatografia de Fase Reversa/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos
18.
Artigo em Inglês | MEDLINE | ID: mdl-31915109

RESUMO

An liquid chromatography-mass spectrometry (LC-MS/MS) assay was developed for the combined analysis of the five poly (ADP-ribose) polymerase (PARP) inhibitors niraparib, olaparib, rucaparib talazoparib and veliparib. A simple and fast sample pre-treatment method was used by protein precipitating of plasma samples with acetonitrile and dilution of the supernatant with formic acid (0.1% v/v in water). This was followed by chromatographic separation on a reversed-phase UPLC BEH C18 column and detection with a triple quadrupole mass spectrometer operating in the positive mode. A simplified validation procedure specifically designed for bioanalytical methods for clinical therapeutic drug monitoring (TDM) purposes, was applied. This included assessment of the calibration model, accuracy and precision, lower limit of quantification (LLOQ), specificity and selectivity, carry-over and stability. The validated range was 30-3000 ng/mL for niraparib, 100-10,000 ng/mL for olaparib, 50-5000 ng/mL for rucaparib, 0.5-50 ng/mL for talazoparib and 50-5000 for veliparib. All results were within the criteria of the US Food and Drug Administration (FDA) guidance and European Medicines Agency (EMA) guidelines on method validation. The assay has been successfully implemented in our laboratory.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Monitoramento de Medicamentos/métodos , Inibidores de Poli(ADP-Ribose) Polimerases/sangue , Espectrometria de Massas em Tandem/métodos , Benzimidazóis/sangue , Cromatografia de Fase Reversa/métodos , Compostos Heterocíclicos com 1 Anel/sangue , Humanos , Indóis/sangue , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes
19.
Anal Bioanal Chem ; 412(7): 1483-1495, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31965244

RESUMO

The focus of this study was the analysis of the complex chemical composition from different parts of Buddleja davidii, whose species are commonly known as ornamental plants and herbal medicines in many countries. As an herbal medicine, it has been utilized for stroke treatments, headache, wound healing, neurological disorder, etc. However, the understanding of its chemical matrices is still insufficient. Therefore, an online two-dimensional reversed phase liquid chromatography x hydrophilic interaction liquid chromatography (RPLCxHILIC) system coupled with mass spectrometry was applied for further detailed investigation of the chemical constituents in Buddleja dividii. In this two-dimensional liquid chromatography (2D-LC) method, a new at-column dilution (ACD) modulator was introduced in the 2D-LC system to solve the incompatibility problem of the mobile phase between two dimensions, which resulted in a 2D-LC analysis with high orthogonality. For the root extract, as one of the analyzed samples, the optimization of the 1D and 2D gradients was carried out carefully. With this new modulator, much better peak separation and better peak shape were achieved compared to two-dimensional liquid chromatography system using a traditional standard (TS) modulator. With a similar approach, the other four parts of Buddleja davidii were well separated. Comparing the different analyzed parts, flowers and leaves showed the most complex profiles. MS and MS/MS data were obtained successfully, which demonstrated the potential of the proposed RPLCxHILIC-MS system in the constituents' analysis of herbal medicine. However, due to the lack of reported reference information, 24 compounds could be tentatively identified.


Assuntos
Buddleja/química , Cromatografia de Fase Reversa/métodos , Medicamentos de Ervas Chinesas/química , Interações Hidrofóbicas e Hidrofílicas , Técnicas de Diluição do Indicador , Espectrometria de Massas em Tandem/métodos
20.
Anal Bioanal Chem ; 412(8): 1795-1806, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31982923

RESUMO

Biopharmaceuticals are in direct contact with different plastic materials, which can contribute to process-related impurities. Polyethylene terephthalate glycol (PETG) is used for storage and transportation of biopharmaceuticals and it is synthetized from the poly-condensation reaction between ethylene glycol, 1,4-cyclodimethanol and dimethyl terephthalate. PETG bottles are analyzed for such impurities prior to release; however, the nature of the pharmaceutical matrix can extract impurities, so it is important to measure these contaminants in biopharmaceuticals. This study shows a liquid chromatography method for the quantification of ethylene glycol in PETG materials as an alternative to the standard USP colorimetric method. The method is based on the derivatization of ethylene glycol with benzoyl chloride in a Schotten-Baumann reaction. We present a comprehensive method development and validation. The method allows the detection and quantification of leached and extracted ethylene glycol directly in biopharmaceuticals after years of storage in contact with PETG bottles. Results showed residual ethylene glycol in drug substances to a level of ≈  0.1-0.5 µg/mL exposed during 2-6 years of storage in PETG bottles and ≈ 0.2-0.9 µg/mL in biopharmaceuticals. Graphical abstract Biopharmaceuticals must be free or low concentration for leachables, FR-UHPLC-UV analysis is a precise and accurate analytical method for ethylene glycol measurement. This leachable is commonly present in products in direct contact with PETG plastic.


Assuntos
Produtos Biológicos/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Etilenoglicol/análise , Limite de Detecção , Plásticos/química , Polímeros/química , Reprodutibilidade dos Testes
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