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1.
Food Chem ; 321: 126692, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32251923

RESUMO

In this work, we describe for the first time the presence of selenoprotein P in human breast milk. To this end, a novel analytical method has been developed based on a two-dimensional column switching system, which consisted of three size exclusion columns and one affinity column coupled to inductively coupled plasma mass spectrometry (ICP-MS). The method combines the accurate quantification of selenoproteins and selenometabolites by species unspecific isotopic dilution ICP-MS, with unequivocal identification by quadrupole-time-of-flight mass spectrometry. Several selenopeptides, which contain the amino acid selenocysteine (U, SeCys), were identified after tryptic digestion followed by their separation. The results reveal that the relative selenium concentration in colostrum follows the order: glutathione peroxidase (GPX) ≈ selenoprotein P (SELENOP) > selenocystamine (SeCA) > other selenometabolites (SeMB), in contrast with previously published papers (GPX > SeCA > selenocystine > selenomethionine). A mean concentration of 20.1 ± 1.0 ng Se g-1 as SELENOP (1.45 µg SELENOP/g) was determined in colostrum (31% of total selenium).


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Leite Humano/química , Selenoproteína P/análise , Cromatografia de Afinidade , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão/instrumentação , Feminino , Glutationa Peroxidase/metabolismo , Humanos , Selênio/análise , Selenocisteína/análise , Selenocisteína/química , Selenometionina/análise , Selenoproteínas/análise
2.
Biochemistry ; 59(12): 1242-1251, 2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-32163271

RESUMO

Ganglioside GM3 is a sialylated membrane-based glycosphingolipid that regulates insulin receptor signaling via direct association with the receptor. The level of expression of GM3 synthase (GM3S) and GM3 is increased in tissues of patients with diabetes and murine models of diabetes, and obesity-induced insulin resistance is attenuated in GM3S-deficient mice. Therefore, GM3S has been considered a therapeutic target for type II diabetes; however, no GM3S inhibitors have been reported to date. In this study, we established a high-throughput scintillation proximity assay that can detect GM3S activity to screen GM3S inhibitors from our original chemical library. We also established methods for detecting the activity of GM3S and another sialyltransferase, ST3Gal3, through direct measurement of the enzyme products using an automatic rapid solid-phase extraction system directly coupled to a mass spectrometer. Consequently, we successfully identified two different chemotypes of GM3S-selective inhibitors with a mixed mode of inhibition. We believe that these compounds can be further developed into drugs to treat or prevent diabetes as well as contribute to the development of the ganglioside research field.


Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Gangliosídeo G(M3)/biossíntese , Ensaios de Triagem em Larga Escala/métodos , Hipoglicemiantes/farmacologia , Sialiltransferases/antagonistas & inibidores , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Diabetes Mellitus Tipo 2/metabolismo , Ensaios Enzimáticos , Ensaios de Triagem em Larga Escala/instrumentação , Humanos , Hipoglicemiantes/uso terapêutico , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Sialiltransferases/genética , Sialiltransferases/isolamento & purificação , Sialiltransferases/metabolismo , Espectrometria de Massas em Tandem/instrumentação , Espectrometria de Massas em Tandem/métodos
3.
Anal Chim Acta ; 1102: 46-52, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32043995

RESUMO

The electrochemical flow cell containing track-etched microporous membrane electrodes was applied to a dual-electrode coulometric detector for microbore/capillary HPLC with a small injection volume and low eluent flow rate. The proposed flow cell with a 0.1-mm diameter inlet channel gave a detection volume of 0.08 nL per electrode, which was determined by the eluent flow through the electrode. For the dual-electrode detector, the calculated volume was 0.24 nL. The efficiency of electrooxidation of l-ascorbic acid increased as the flow rate decreased and was close to 100% when the flow rate was below 50 µL min-1, which is a common flow rate in microbore or capillary liquid chromatography. Catecholamines, such as noradrenaline, adrenaline, and dopamine, were detected by total conversion with two-electron oxidation in the potential range from 0.8 to 1.0 V vs. Ag/AgCl after separation with a microbore column. These peaks were accompanied by corresponding cathodic peaks derived from quasi-stable electrooxidation products of the catecholamines. The detection limits of noradrenaline, adrenaline, and dopamine were 0.1, 0.1, and 0.2 µM, respectively. The RSD values for five replicate measurements of 5.0 µM of these compounds were 0.9%, 0.7%, and 1.5%, respectively. Coulometric detection was also demonstrated by determination of catecholamines in pharmaceuticals.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Técnicas Eletroquímicas/métodos , Eletrodos , Membranas Artificiais , Ácido Ascórbico/química , Cromatografia Líquida de Alta Pressão/instrumentação , Dopamina/análise , Dopamina/química , Técnicas Eletroquímicas/instrumentação , Epinefrina/análise , Epinefrina/química , Limite de Detecção , Norepinefrina/análise , Norepinefrina/química , Oxirredução
5.
J Agric Food Chem ; 68(8): 2588-2596, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32031793

RESUMO

Monosaccharides play important roles in plant growth and development, and their biofunctions are closely related to their endogenous contents. Therefore, the determination of monosaccharides is beneficial for the further study of monosaccharide biofunction. In this work, we developed a liquid chromatography-mass spectrometry analytical method assisted by a post-column derivatization technique (LC-PCD-MS) for the fast and automatic determination of 16 monosaccharides in samples. Post-column chemical derivatization of monosaccharides was performed by a reaction of monosaccharides with 4-benzylaminobenzeneboronic acid (4-PAMBA) through boronate ester formation in a three-way connector. 4-PAMBA worked as a derivatization reagent to improve the selectivity and sensitivity of monosaccharide detection by MS. The developed LC-PCD-MS method integrates LC separation, chemical derivatization, and MS detection in one run, thus greatly reducing the analysis time for each sample. The limits of detection and limits of quantification for 16 monosaccharides were in the range of 0.002-0.1 and 0.007-0.5 ng/mL, respectively. Good linearity was obtained from the linear regression, with a determination coefficient (R2) ranging from 0.9928 to 1.0000. The relative recoveries were in the range of 80.7-117.8%, with the intra- and interday relative standard deviations less than 19.7 and 16.5%, respectively, indicating good accuracy and acceptable reproducibility of the method. Finally, the method was successfully applied to investigate the spatial and temporal distribution of 16 monosaccharides in the developing flower and germinating seed of Arabidopsis thaliana.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Monossacarídeos/análise , Espectrometria de Massas em Tandem/métodos , Arabidopsis/química , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Cromatografia Líquida de Alta Pressão/instrumentação , Flores/química , Flores/crescimento & desenvolvimento , Flores/metabolismo , Limite de Detecção , Monossacarídeos/metabolismo , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Espectrometria de Massas em Tandem/instrumentação
6.
Drug Dev Ind Pharm ; 46(2): 209-218, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31933394

RESUMO

Empagliflozin (EGF) received USFDA approval in 2014 for oral use to control the glucose levels in adults with type 2 diabetes mellitus. Albeit, a systematic drug-excipient compatibility study of EGF has not been reported in the open literature. As physical and chemical interactions affect the performance of the formulation, this study intended to unveil the drug and excipients interactions which would later help in development of a robust solid dosage form. Differential scanning calorimetry (DSC) was applied as a screening tool for the assessment of compatibility between EGF and the list of excipients mentioned in the EMEA summary of product characteristics (SmPC)-section 6.1, along with mannitol and polyvinylpyrrolidone. Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Powder Diffraction (PXRD) and Hot Stage Microscopy (HSM) methods were utilized to appraise the interpretation of DSC results adequately. Isothermal stress testing (IST) studies of EGF were performed using the selected excipients to check the presence of interaction products (IPs) and the drug content by HPLC. Additional peaks were observed in the EGF-macrogol mixture than the drug peak in the HPLC analysis after two and half months, and those were separated and identified by the Ultra-High Performance Liquid Chromatography-Quadrupole Time of Flight Mass Spectrometry (UHPLC-QTOF-MS). Overall, EGF had shown compatibility with 13 selected excipients; however, initial observation of DSC and IST studies indicated plausible interaction of the EGF with macrogol.


Assuntos
Compostos Benzidrílicos/química , Excipientes/química , Glucosídeos/química , Varredura Diferencial de Calorimetria/métodos , Química Farmacêutica/métodos , Cromatografia Líquida de Alta Pressão/instrumentação , Formas de Dosagem , Manitol/química , Povidona/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos
7.
J Pharm Biomed Anal ; 180: 113064, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31896521

RESUMO

Recently, the development of cyclic peptide drugs has accelerated. To develop an analytical method to determine the physicochemical properties of these lipophilic drug candidates, we investigated the separation mechanism of cyclosporine congeners A, B, C, and D using HPLC with a column packed with 2-µm nonporous octadecylsilyl silica particles at high temperature. The four congeners were eluted with good repeatability in terms of retention time, peak area, and theoretical plate number. A difference of one amino acid in the eleven amino-acid sequence of the cyclosporine congeners was able to be recognized by our system within 4 min by isocratic elution, and the resolution was greater than 1.68. The calculated logP values of these congeners were well correlated with the retention factors with a correlation coefficient of 0.991. We could elucidate the separation mechanism of cyclosporine congeners on the high-temperature HPLC system. These results show that this method using HPLC on a column packed with 2-µm nonporous octadecylsilyl silica particles can be used for studying the lipophilicity of cyclosporine congeners.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Ciclosporina/análise , Dióxido de Silício/química , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão/instrumentação , Ciclosporina/química , Temperatura Alta , Isomerismo , Lipídeos/química , Propriedades de Superfície
8.
J Agric Food Chem ; 68(3): 892-898, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31891506

RESUMO

This study described a simple, specific, and sensitive method using immunoaffinity magnetic purification coupled with high-performance liquid chromatography-fluorescence (HPLC-FL) detection for determination of bovine lactoferrin (bLf) in dairy products. BLf was selectively extracted from dairy products using immunoaffinity beads and then detected by HPLC-FL with its intrinsic fluorescence. During the analysis, standard solutions of bLf were pretreated with Tween 20, an anti-adsorptive agent, for blocking the nonspecific binding of bLf to polypropylene tubes. The calibration curve was linear over the range of 0.8-30 µg mL-1. The validated method was successfully applied to measure bLf at the intact level in dairy products.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Laticínios/análise , Imunoensaio/métodos , Lactoferrina/análise , Lactoferrina/isolamento & purificação , Magnetismo/métodos , Animais , Bovinos , Cromatografia Líquida de Alta Pressão/instrumentação , Fluorescência
9.
Artigo em Inglês | MEDLINE | ID: mdl-31896073

RESUMO

Rapid discovery of active ingredients from complex matrices is one of great challenges for modern drug development. Traditional methods often require many sample treatment steps, including an extraction step with exclusively dedicated solvents followed by repeated separation and activities assessment. This present work described an integrated analytical setup for natural antioxidants discovery in which the online extraction (OLE) of a solid sample is directly coupled to its analysis by high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry and 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) antioxidant assay (OLE-HPLC-DAD-QTOF-MS/MS-ABTS). This developed approach makes sample extraction, chromatographic separation and chemical detection, and antioxidant assay integrated into a single HPLC injection and was successfully applied for the rapid discovery of natural antioxidant bioactives from Polygonum viviparum. A total of 21 secondary metabolites were characterized according to their retention times, ultraviolet (UV) spectra, exact mass and fragmentation ions in MS/MS spectra, and 18 of them displayed antioxidant activity (response as negative peaks in antioxidant assay). This work describes a simple, green and efficient approach to minimize the sample consumption (only 0.4 mg was required) and eliminate complex sample treatment procedures. The developed OLE-HPLC-DAD-QTOF-MS/MS-ABTS system offers new perspectives for rapid chemical profiling of natural products and their antioxidants discovery.


Assuntos
Antioxidantes/análise , Cromatografia Líquida de Alta Pressão/instrumentação , Microextração em Fase Líquida/instrumentação , Polygonum/química , Espectrometria de Massas em Tandem/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Desenho de Equipamento , Microextração em Fase Líquida/métodos , Extratos Vegetais/química , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos
10.
J Sep Sci ; 43(3): 631-638, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31680400

RESUMO

The first dispersive liquid liquid microextraction scheme followed by liquid chromatography-post column derivatization for the determination of the antiviral drug rimantadine in urine samples is demonstrated. The effect of the type and volume of organic extraction solvent, type and volume of disperser solvent, sample pH, ionic strength, extraction time, and centrifugation speed on the extraction efficiency were studied. Rimantadine and the internal standard (amantadine) were chromatographed using a reversed phase monolithic stationary phase with a mixture of equal volumes of methanol and phosphate buffer (pH = 3) as mobile phase. On-line post-column derivatization of the analyte was performed using a "two-stream" manifold with o-phthalaldehyde and N-acetyl-cysteine at alkaline medium. Under the optimized extraction conditions, the enrichment factor of rimantadine was 58. The linear range was 5-100 µg/L with correlation coefficient r of 0.9984 while the limit of detection achieved was 0.5 µg/L. The within-day and between-day precision for the tested concentration levels were less than 14.3% and the mean recoveries obtained from the spiked samples were ranged between 87.5 and 113.9%. The main advantages of the proposed method are the simplicity of operation, rapidity, low cost, and low limit of detection of the analyte.


Assuntos
Microextração em Fase Líquida , Rimantadina/urina , Cromatografia Líquida de Alta Pressão/instrumentação , Voluntários Saudáveis , Humanos , Microextração em Fase Líquida/instrumentação
11.
Chirality ; 32(1): 42-52, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31688990

RESUMO

Bath salts, fumigations, cleaners and air fresheners, behind these terms substances are hidden, which count as "Legal Highs". These fancy names are used to pretend Legal Highs as harmless compounds, to circumvent legal regulations for marketing as well as to increase the sales. Besides classic illicit drugs of synthetic origin such as amphetamines, cocaine and MDMA, the trade of these compounds, also known as new psychoactive substances (NPS), is not uncommon today. In many countries, NPS are still not subject to drug control. Among them, there are stimulants such as new amphetamine derivatives or cathinones, which possess a chiral centre. Little is known about the fact that the two possible enantiomers may differ in their pharmacological effect. The aim of this study was to test a novel HPLC column for the enantioseparation of a set of 112 NPS coming from different chemical groups and collected by internet purchases during the years 2010-2018. The CSP, namely Lux® 5 µm i-Amylose-1, LC Column 250 x 4.6 mm, was run in normal phase mode under isocratic conditions, UV detection was performed at 245 nm and 230 nm, injection volume was 10 µl and flow rate was 1 ml/min. With a mobile phase consisting of n-hexane/isopropanol/diethylamine (90:10:0.1), herein, 79 NPS were resolved into their enantiomers successfully, for 37 of them baseline resolution was achieved. After increase of lipophily of the mobile phase to 99:1:0.1, another 27 compounds were baseline separated. It was found that all separated NPS are traded as racemic compounds.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Drogas Desenhadas/química , Drogas Desenhadas/isolamento & purificação , Alcaloides/química , Alcaloides/isolamento & purificação , Anfetamina/química , Anfetamina/isolamento & purificação , Amilose/química , Cromatografia Líquida de Alta Pressão/métodos , Reprodutibilidade dos Testes , Estereoisomerismo
12.
Drug Res (Stuttg) ; 70(1): 12-22, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31539916

RESUMO

Bepotastine besilate (here after referred to as BTST), chemically known as ({d(S)4[4[(4chlorophenyl) (2pyridyl) methoxy] piperidino} butyric acid monobenzene sulphonate), is a second-generation antihistamine drug. To the best of our knowledge, no studies concerning the isolation or identification of process-related impurities have been reported so far. The current study reports the development and validation of a stability-indicating RP-HPLC method for the separation and identification of 5 potential impurities in bepotastine besilate. In this experiment, the structures of 3 process-related impurities were found to be new compounds. They were characterized and confirmed by NMR and MS spectroscopy analyses. These 3 new compounds were proposed to be (S)-4-[(phenyl)-2-pyridinylmethoxy]-1-piperidinebutanoic acid,(Imp-A); 4-[(S)-(4-chlorophenyl)-2-pyridinylmethoxy]-1- piperidinebutyric acid, N-oxide (Imp-B) and (S)-4-[(4- chlorophenyl)-2-pyridinylmethoxy]-1-piperidylethane (Imp-C). In addition, an efficient optimized chromatographic method was performed on a Shimadzu Inertsil C8-3 column (150 mm×4.6 mm, 3 µm) to separate and quantify these 5 impurities. It was using 15 mmol ammonium formate buffer in water (pH adjusted to 3.8 with formic acid) and acetonitrile as the mobile phase in gradient mode. The method was developed to separate and quantify these 5 impurities obtained in the range of 0.05-0.75 µg/mL. It was validated and proven to be selective, accurate and precise and suitable. It is the first publication of identification and characterization data of the 3 new compounds. It is also the first effective HPLC method for separation and quantification of all of process-related impurities in bepotastine besilate.


Assuntos
Antialérgicos/análise , Composição de Medicamentos/normas , Contaminação de Medicamentos/prevenção & controle , Piperidinas/análise , Piridinas/análise , Antialérgicos/normas , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Espectroscopia de Ressonância Magnética , Piperidinas/normas , Piridinas/normas , Espectrometria de Massas em Tandem
13.
J Chromatogr A ; 1611: 460575, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31607445

RESUMO

Improvements in sample preparation, separation, and mass spectrometry continue to expand the coverage in LC-MS based lipidomics. While longer columns packed with smaller particles in theory give higher separation performance compared to shorter columns, the implementation of this technology above commercial limits has been sparse due to difficulties in packing long columns and successfully operating instruments at ultrahigh pressures. In this work, a liquid chromatograph that operates up to 35 kpsi was investigated for the separation and identification of lipid species from human plasma. Capillary columns between 15-50 cm long were packed with 1.7 µm BEH C18 particles and evaluated for their ability to separate lipid isomers and complex lipid extracts from human plasma. Putative lipid class identifications were assigned using accurate mass and relative retention time data of the eluting peaks. Our findings indicate that longer columns packed and operated at 35 kpsi outperform shorter columns packed and run at lower pressures in terms of peak capacity and numbers of features identified. Packing columns with relatively high concentration slurries (200 mg/mL) while sonicating the column resulted in 6-34% increase in peak capacity for 50 cm columns compared to lower slurry concentrations and no sonication. For a given analysis time, 50 cm long columns operated at 35 kpsi provided a 20-95% increase in chromatographic peak capacity compared with 15 cm columns operated at 15 kpsi. Analysis times up to 4 h were evaluated, generating peak capacities up to 410 ±â€¯5 (n = 3, measured at 4σ) and identifying 480 ±â€¯85 lipids (n = 2). Importantly, the results also show a correlation between the peak capacity and the number of lipids identified from a human plasma extract. This correlation indicates that ionization suppression is a limiting factor in obtaining sufficient signal for identification by mass spectrometry. The result also shows that the higher resolution obtained by shallow gradients overcomes possible signal reduction due to broader, more dilute peaks in long gradients for improving detection of lipids in LC-MS. Lastly, longer columns operated at shallow gradients allowed for the best separation of both regional and geometrical isomers. These results demonstrate a system that enables the advantages of using longer columns packed and run at ultrahigh pressure for improving lipid separations and lipidome coverage.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Lipidômica/métodos , Lipídeos/química , Espectrometria de Massas/métodos , Cromatografia Líquida de Alta Pressão/instrumentação , Humanos , Lipidômica/instrumentação , Lipídeos/sangue , Espectrometria de Massas/instrumentação , Sonicação
14.
J Chromatogr A ; 1611: 460574, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31591039

RESUMO

Sixteen pairs of enantiomeric dipeptides were separated on four chiral ion-exchanger-type stationary phases based on Cinchona alkaloids. Anion-exchangers (QN-AX, QD-AX) and zwitterionic phases [ZWIX(+)™ and ZWIX(-)™] were studied in a comparative manner. The effects of the nature and concentrations of the mobile phase solvent components and organic salt additives on analyte retention and enantioseparation were systematically studied in order to get a deeper insight into the enantiorecognition mechanism. Moreover, experiments were performed in the temperature range 10-50 °C to calculate thermodynamic parameters like changes in standard enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°) on the basis of van't Hoff plots derived from the ln α vs. 1/T curves. Elution sequences of the dipeptides were determined in all cases and, with a few exceptions, they were found to be opposite on the pseudoenantiomeric stationary phases as of QN-AX/QD-AX and of ZWIX(+) and ZWIX(-). The stereoselective retention mechanism is based on electrostatically driven intermolecular interactions supported by additional interaction increments mainly determined by the absolute configuration of the chiral C8 and C9 atoms of the quinine and quinidine moieties.


Assuntos
Alcaloides de Cinchona/química , Cinchona/química , Dipeptídeos/química , Extratos Vegetais/química , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Estereoisomerismo , Temperatura , Termodinâmica
15.
J Chromatogr A ; 1611: 460594, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31635787

RESUMO

van 't Hoff plots (logarithm of the retention factor, ln k, vs. the reciprocal of absolute temperature, 1/T) are commonly used in chromatographic studies to characterize the retention mechanisms based on the determined enthalpy (ΔH∘) and entropy (ΔS∘) change of analyte adsorption. In reversed phase liquid chromatography, the thermodynamic parameters could help to understand the retention mechanism. In chiral chromatography, however, the conclusions drawn based on van 't Hoff plots can be deceptive because several different types of adsorption sites are present on the surface of stationary phase. The influence of heterogeneity, however, cannot be studied experimentally. In this study, we employed two reversed phase columns with different retention mechanisms to show that by serially coupling the columns, the obtained thermodynamic parameters are not related to the results obtained on the respective individual columns. Furthermore, our results show that the experimental conditions - such as flow-rate or choice of instrument - will strongly influence the calculated enthalpy and entropy values.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia de Fase Reversa/instrumentação , Adsorção , Estereoisomerismo , Temperatura , Termodinâmica
16.
J Sep Sci ; 43(4): 696-707, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31724311

RESUMO

An updated and improved method for analysis of omeprazole/esomeprazole and related substances on core-shell columns was developed using Fusion LC Method Development™. The method was optimized with respect to column type, column temperature, mobile phase pH level, and gradient time. Four different core-shell columns were examined to develop a method suitable for both high performance- and ultra-high performance liquid chromatography using a Quality by Design approach. The final method offers two alternative columns: Poroshell EC C18 (3.0 × 100 mm, 2.7 µm) or Poroshell HPH (3.0 × 100 mm, 2.7 µm) with the same gradient elution condition and mobile phase composition. Total run time is 18 min with 12 min of gradient elution. Phosphate buffer (15 mM, pH 7.8) is selected as the aqueous mobile phase and acetonitrile as the organic mobile phase. Column temperature is set at 40°C and ultraviolet detection at 302 nm. Furthermore, by studying parameters in a systematic way, an understanding of the effect of the input parameters enhances the method robustness and should allow for regulatory flexibility in terms of post-approval changes. Compared to the current United States Pharmacopeia method, the updated method is faster, more efficient and performs well above acceptance criteria.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Esomeprazol/isolamento & purificação , Omeprazol/isolamento & purificação , Cromatografia Líquida de Alta Pressão/instrumentação , Esomeprazol/análise , Omeprazol/análise , Temperatura
17.
J Agric Food Chem ; 68(3): 876-883, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31670510

RESUMO

A chemical-derivatization-triggered aggregation-induced emission (AIE) method for the highly selective determination of hydrogen sulfide (H2S) in wine matrices by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed. The detection strategy was developed based on the chemical derivatization of H2S using a low-cost AIE-active fluorescence derivatization reagent, N-(3-iodine-2-oxopropyl)pyrene methamine (NIPM), to trigger specific AIE at 475 nm, which was red-shifted sharply to the maximum emission wavelength as compared with NIPM monomers of 375 nm, effectively quenching the interference from other thiol-containing compounds. With the aid of specific AIE and the effective separation of HPLC, the proposed method showed high selectivity and sensitivity toward H2S. The limits of detection (LODs) at the sub-nM level of 0.25 nmol/L in the wine-beer sample and 0.30 nmol/L in red wine sample were obtained. To certify its applicability, this proposed strategy was successfully applied for the determination of H2S in wine matrices.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sulfeto de Hidrogênio/análise , Vinho/análise , Cromatografia Líquida de Alta Pressão/instrumentação , Fluorescência , Limite de Detecção
18.
J Chromatogr A ; 1609: 460461, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31445805

RESUMO

α-Linolenic acid (ALA) and its most important positional isomer γ-linolenic acid (GLA), are essential fatty acids (vitamin F). Therefore, ALA- and GLA-rich edible oils hold great potential in human and animal nutrition, as well as in nutraceutics and cosmetics. Quality control and nutritional validation of oil products is thus of increasing importance. In the present study, the cellulose tris(3,5-dichlorophenylcarbamate)-based chiral stationary phase was successfully used for separation of ALA and GLA, a major challenge in the liquid chromatography of these isomers. The chromatographic conditions were firstly optimized on a HPLC system with UV detection, and the use of a reversed-phase eluent system made up of aqueous 10 mM ammonium acetate/acetonitrile (40/60, v/v; wspH6.0) with a 25 °C column temperature resulted optimal for the simultaneous discrimination of the two isomers at a 0.5 mL/min flow rate (α = 1.10; RS = 1.21). The method was then optimized for LC-MS/MS implementation. The proposed innovative separation method holds a great potential for the quantification of ALA and GLA in food and biological matrices, thus opening the way to further investigations involving the two positional isomers.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Ácido alfa-Linoleico/isolamento & purificação , Ácido gama-Linolênico/isolamento & purificação , Celulose/análogos & derivados , Celulose/química , Cromatografia Líquida de Alta Pressão/instrumentação , Humanos , Isomerismo , Fenilcarbamatos/química , Espectrometria de Massas em Tandem , Temperatura , Ácido alfa-Linoleico/química , Ácido gama-Linolênico/química
19.
Intern Med ; 59(6): 805-809, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31787693

RESUMO

We herein report a 50-year-old Chinese woman with Hb Phnom Penh (α117Phe-Ile-α118Thr) showing high or reasonable HbA1c values depending on the type of high-performance liquid chromatography (HPLC) system. A high HbA1c value of 7.5% (HPLC assay: G9) and a reasonable HbA1c value of 5.2% (assay unknown) were observed. Therefore, the patient was refereed to our hospital; the oral glucose tolerance test showed normal glucose tolerance. The HbA1c values measured by an enzymatic assay, immunoassay, and affinity assay, as well as most HPLC assays were within the reference range, whereas those measured by the Tosoh HPLC systems were high.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Hemoglobina A Glicada/análise , Hemoglobinas Anormais/análise , Feminino , Teste de Tolerância a Glucose , Humanos , Imunoensaio , Pessoa de Meia-Idade , Sensibilidade e Especificidade
20.
J Pharm Biomed Anal ; 177: 112851, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31499427

RESUMO

A high performance liquid chromatographic method was developed for the simultaneous determination of the related substances (R-ivabradine, dehydro-S-ivabradine, N-demethyl-S-ivabradine, ((S)-3,4-dimethoxy-bicyclo[4.2.0]octa-1,3,5-triene-7-yl-methyl)-methyl-amine) and 1-(7,8-dimethoxy-1,3,4,5-tetrahydro-2H-3-benzazepine-2-on-3-yl)-3-chloro-propane) of the heart-rate lowering drug, ivabradine. The separation capability of seven different polysaccharide-type chiral columns (Lux Amylose-1, Lux i-Amylose-1, Lux Amylose-2, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3 and Lux Cellulose-4) was investigated with a mobile phase consisting of 0.1% diethylamine in methanol, 2-propanol and acetonitrile. During the screnning experiments the best results were obtained on Lux Cellulose-2 (based on cellulose tris(3-chloro-4-methylphenylcarbamate) column with methanol with an ideal case, where all the impurities eluted before the S-ivabradine peak. Chromatographic parameters (flow rate, temperature and mobile phase constituents) were optimized by a full factorial screening design. Using optimized parameters (Lux Cellulose-2 column with 0.06% (v/v) diethylamine in methanol/acetonitrile 98/2 (v/v) with 0.45 mL/min flow rate at 12 °C) baseline separations were achieved between all compounds. The optimized method was validated according to the International Council on Harmonization Q2(R1) guideline and proved to be reliable, linear, precise and accurate for determination of at least 0.05% for all impurities in S-ivabradine samples. Method application was tested on a commercial tablet formulation and proved to be suitable for routine quality control of both chiral and achiral related substances of S-ivabradine.


Assuntos
Composição de Medicamentos/normas , Contaminação de Medicamentos/prevenção & controle , Ivabradina/análise , Controle de Qualidade , Celulose/análogos & derivados , Celulose/química , Química Farmacêutica , Cromatografia Líquida de Alta Pressão/instrumentação , Ivabradina/química , Fenilcarbamatos/química , Estereoisomerismo , Comprimidos , Temperatura
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