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1.
Molecules ; 23(10)2018 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-30340402

RESUMO

Proanthocyanidins are complex polymers of flavan-3-ol monomers and play a key sensory and health role in foods and beverages. We describe here a novel method for characterizing wine proanthocyanidins using a theoretical database comprised of the chemical formula and exact mass of 996 compounds. The database was constructed using the four primary grape and wine proanthocyanidin monomers: (epi)catechin, (epi)catechin-3-O-gallate, (epi)gallocatechin, and (epi)gallocatechin-3-O-gallate, each combined in all possible combinations up to a polymerization of 10. The database was queried against spectra collected using ultrahigh performance liquid chromatography (UHLPC) with a hydrophilic interaction liquid chromatography (HILIC) column and coupled to a high-resolution accurate mass quadrupole time-of-flight mass spectrometer (Q-TOF MS). Two wine samples produced with different post fermentation maceration were analyzed using the presented method to demonstrate application for analysis of diverse proanthocyanidins. The first sample was pressed immediately at the end of fermentation when all sugar had been utilized and the second received eight weeks of post fermentation maceration. The HILIC column combined with high resolution tandem mass spectrometry and database matching provided tentative identification of 89 compounds with excellent resolution and without the need for two-dimensional separations. The identified compounds were visualized with Kendrick mass analysis, a simple technique allowing for rapid visualization of which compounds are present in a given sample.


Assuntos
Amidas/química , Proantocianidinas/isolamento & purificação , Vitis/química , Vinho , Catequina/análogos & derivados , Catequina/química , Catequina/metabolismo , Cromatografia Líquida , Bases de Dados de Compostos Químicos , Interações Hidrofóbicas e Hidrofílicas , Espectrometria de Massas , Proantocianidinas/química , Proantocianidinas/metabolismo , Vitis/metabolismo
2.
Anal Bioanal Chem ; 409(10): 2639-2653, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28224246

RESUMO

Veterinary drug residues in animal-derived foods must be monitored to ensure food safety, verify proper veterinary practices, enforce legal limits in domestic and imported foods, and for other purposes. A common goal in drug residue analysis in foods is to achieve acceptable monitoring results for as many analytes as possible, with higher priority given to the drugs of most concern, in an efficient and robust manner. The U.S. Department of Agriculture has implemented a multiclass, multi-residue method based on sample preparation using dispersive solid phase extraction (d-SPE) for cleanup and ultrahigh-performance liquid chromatography-tandem quadrupole mass spectrometry (UHPLC-QQQ) for analysis of >120 drugs at regulatory levels of concern in animal tissues. Recently, a new cleanup product called "enhanced matrix removal for lipids" (EMR-L) was commercially introduced that used a unique chemical mechanism to remove lipids from extracts. Furthermore, high-resolution quadrupole-time-of-flight (Q/TOF) for (U)HPLC detection often yields higher selectivity than targeted QQQ analyzers while allowing retroactive processing of samples for other contaminants. In this study, the use of both d-SPE and EMR-L sample preparation and UHPLC-QQQ and UHPLC-Q/TOF analysis methods for shared spiked samples of bovine muscle, kidney, and liver was compared. The results showed that the EMR-L method provided cleaner extracts overall and improved results for several anthelmintics and tranquilizers compared to the d-SPE method, but the EMR-L method gave lower recoveries for certain ß-lactam antibiotics. QQQ vs. Q/TOF detection showed similar mixed performance advantages depending on analytes and matrix interferences, with an advantage to Q/TOF for greater possible analytical scope and non-targeted data collection. Either combination of approaches may be used to meet monitoring purposes, with an edge in efficiency to d-SPE, but greater instrument robustness and less matrix effects when analyzing EMR-L extracts. Graphical abstract Comparison of cleanup methods in the analysis of veterinary drug residues in bovine tissues.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Resíduos de Drogas/análise , Lipídeos/análise , Espectrometria de Massas em Tandem/métodos , Drogas Veterinárias/análise , Animais , Bovinos , Resíduos de Drogas/química , Resíduos de Drogas/isolamento & purificação , Rim/metabolismo , Lipídeos/química , Lipídeos/isolamento & purificação , Fígado/metabolismo , Músculo Esquelético/metabolismo , Extração em Fase Sólida , Distribuição Tecidual , Drogas Veterinárias/química , Drogas Veterinárias/isolamento & purificação
3.
Anal Chem ; 88(7): 3617-23, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-26938581

RESUMO

The ability to identify contaminants or adulterants in diverse, complex sample matrixes is necessary in food safety. Thus, nontargeted screening approaches must be implemented to detect and identify unexpected, unknown hazardous compounds that may be present. Molecular formulas can be generated for detected compounds from high-resolution mass spectrometry data, but analysis can be lengthy when thousands of compounds are detected in a single sample. Efficient data mining methods to analyze these complex data sets are necessary given the inherent chemical diversity and variability of food matrixes. The aim of this work is to determine necessary requirements to successfully apply data analysis strategies to distinguish suspect and control samples. Infant formula and orange juice samples were analyzed with one lot of each matrix containing varying concentrations of a four compound mixture to represent a suspect sample set. Small molecular differences were parsed from the data, where analytes as low as 10 ppb were revealed. This was accomplished, in part, by analyzing a quality control standard, matrix spiked with an analytical standard mixture, technical replicates, a representative number of sample lots, and blanks within the sample sequence; this enabled the development of a data analysis workflow and ensured that the employed method is sufficient for mining relevant molecular features from the data.


Assuntos
Contaminação de Medicamentos , Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Fórmulas Infantis/análise , Fórmulas Infantis/química , Espectrometria de Massas , Software , Cromatografia Líquida , Inocuidade dos Alimentos , Humanos , Lactente
4.
Environ Res ; 151: 145-153, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27479711

RESUMO

Perfluoroalkyl substances (PFAS), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are persistent, globally distributed, anthropogenic compounds. The primary source(s) for human exposure are not well understood although within home exposure is likely important since many consumer products have been treated with different PFAS, and people spend much of their lives indoors. Herein, domestic cats were used as sentinels to investigate potential exposure and health linkages. PFAS in serum samples of 72 pet and feral cats, including 11 healthy and 61 with one or more primary disease diagnoses, were quantitated using high-resolution time-of-flight mass spectroscopy. All but one sample had detectable PFAS, with PFOS and perfluorohexane sulfonate (PFHxS) ranging from

Assuntos
Ácidos Alcanossulfônicos/sangue , Caprilatos/sangue , Gatos , Monitoramento Ambiental/métodos , Fluorocarbonos/sangue , Animais , Doenças do Gato/sangue , Habitação , Obesidade/sangue , Animais de Estimação/sangue
5.
J AOAC Int ; 98(2): 330-5, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25905738

RESUMO

The compound yohimbine HCl has been restricted in Australia and categorized as a scheduled prescription drug in other parts of the world, including the United States where it is monographed as a drug in the U. S. Pharmacopeia. However, the bark of the yohimbe plant and its extract is considered a botanical that can be used as a dietary supplement in some parts of the world. For these reasons, methods to characterize the indole alkaloids of the bark and quantify yohimbine and its analogs are presented using accurate mass LC/quadrupole time-of-flight (QTOF)-MS and triple quadrupole LC/MS, respectively. Samples were extracted with a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method to characterize and quantify the indole alkaloids. With the LC/QTOF-MS in auto MS/MS mode the indole alkaloids were identified, and the isomeric response of each could be used to determine whether the actual bark or extract was in samples of dietary supplements and not adulteration with yohimbine HCl. Analogs were identified and include yohimbic acid, methyl yohimbine, and hydroxyl yohimbine. Many isomers of each were also detected, but identified only by the number of chromatographic peaks. Quantification of yohimbine and ajmalicine spiked extracts showed recoveries of 99 to 103% with RSD of 3.6% or lower and LODs of less than 100 ppt. Calibration of the two standards gave r(2) = 0.9999 in a range from 0.1 to 100 ppb. Dietary supplements quantified for these two compounds showed a range from not detected to 3x the amounts found in the bark.


Assuntos
Cromatografia Líquida/métodos , Suplementos Nutricionais/análise , Espectrometria de Massas/métodos , Preparações de Plantas/química , Ioimbina/análogos & derivados , Ioimbina/química , Contaminação de Medicamentos , Contaminação de Alimentos/análise , Estrutura Molecular , Casca de Planta/química , Extratos Vegetais/química
6.
J AOAC Int ; 98(3): 757-759, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26086254

RESUMO

The central nervous system stimulant 1,3-dimethylamylamine (DMAA) has been found in preworkout products and dietary supplements. A fast direct analysis in real time-quadrupole time of flight-MS method was used for identification of DMAA in dietary supplements and to determine if this compound is present in geranium (Pelargonium graveolens) plants or oil. This method involved the use of [M+H]+ ions in the positive mode based on the exact mass of DMAA. The results of this investigation showed that DMAA was not detected from authentic samples of P. graveolens plant material or pelargonium oil or in multiple samples of commercially available pelargonium oil. DMAA was detected in three samples of dietary supplements. The LOD of DMAA was found to be 10 ng/mL.


Assuntos
Aminas/análise , Suplementos Nutricionais/análise , Geranium/química , Limite de Detecção , Espectrometria de Massas , Óleos de Plantas/análise , Plantas/química , Reprodutibilidade dos Testes
7.
J AOAC Int ; 98(1): 13-21, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25857873

RESUMO

Alkaloids have been reported to be the major physiologically active constituents in Mitragyna. An analytical method was developed to provide an alternative, fast method for characterization of alkaloids from various M. speciosa samples. The separation was achieved using an RP octylsilyl (C8) column, MS detection, and a water-acetonitrile with formic acid gradient as the mobile phase. Ultra-HPLC/quadrupole time-of-flight MS analysis and characterization were performed on 12 corynanthe-type indole/oxindole alkaloids obtained from the leaves of M. speciosa Korth. The indoles and oxindoles had an open E ring with or without substitution occurring at the C9 position. The full single mass spectrum of alkaloids showed a strong signal for the protonated molecule [M+H]+. The product ion spectrum of mitragynine type of alkaloids showed strong response at m/z=174.0901 suggestive of an ion containing an odd number of nitrogen atoms corresponding to formula C11H12NO, which is characteristic of indole alkaloids. A multivariate statistical analysis technique, principal component analysis, was used to show discrimination between the M. speciosa samples. The results indicated that the analytical method is suitable for QC testing of various Mitragyna commercial samples and can be used to evaluate market products purported to contain M. speciosa.


Assuntos
Alcaloides/química , Cromatografia Líquida/métodos , Indóis/química , Espectrometria de Massas/métodos , Mitragyna/química , Estrutura Molecular , Oxindóis , Folhas de Planta/química
8.
Planta Med ; 80(4): 321-9, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24510365

RESUMO

Yam (Dioscorea spp.) is an important edible tuber plant used for medicinal purposes to promote health and longevity in Chinese tradition. Steroidal saponins were reported to be the major physiologically active constituents in yams. In this current work, the structural characteristics of steroidal saponins in methanolic extracts from dried rhizomes of two Dioscorea species (D. villosa L. and D. cayenensis Lam.) and dietary supplements have been identified and analyzed using UHPLC/QTOF-MS in both negative and positive ion modes. The fragmentation patterns of reference standards were determined and the steroidal saponins in the extracts were identified or tentatively characterized from their retention times and mass spectra. The fragments produced by collision-induced dissociation (CID) revealed the characteristic cleavage of glycosidic bonds, and the fragmentation pattern provided structural information about the sugars. Twenty-one saponins, including four tentatively identified compounds, were detected in the crude extracts of two Dioscorea species. These saponins can be used to distinguish D. villosa from D. cayenensis. For example, asperin and gracillin are found only in D. cayenensis, and dioscoreavilloside A and B and parvifloside are only found in D. villosa. This can be used to determine the presence or absence of D. villosa in commercial products, which may help determine the spiking of plant material, and/or prevent the use of potentially mislabeled or misidentified "Dioscorea" material. The analytical method also provided an alternative, fast method for quality control of Dioscorea species in dietary supplements. Principal component analysis showed that Dioscorea species and commercial products were easily distinguished. From this a partial least squares model was constructed to determine what species are in different products.


Assuntos
Dioscorea/química , Contaminação de Medicamentos/prevenção & controle , Extratos Vegetais/química , Rizoma/química , Saponinas/análise , Esteroides/análise , Cromatografia Líquida de Alta Pressão/métodos , Suplementos Nutricionais/análise , Dioscorea/classificação , Estrutura Molecular , Análise de Componente Principal , Padrões de Referência , Saponinas/química , Especificidade da Espécie , Espectrometria de Massas por Ionização por Electrospray/métodos , Esteroides/química
9.
Anal Chem ; 85(20): 9581-7, 2013 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-24006925

RESUMO

A detailed evaluation of two liquid chromatography-mass spectrometry techniques, quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS) and triple quadrupole mass spectrometry (LC/MS-MS), was carried out in terms of sensitivity, selectivity, and ionization mode for the detection of sucralose in environmental water samples, which is an important environmental topic in water analysis. Interesting findings were made in regards to fragmentation and sensitivity when both techniques and both ionization modes of operation were compared. In positive ion mode, sucralose was detected by its sodium adduct [M + Na](+) at m/z 419.0038. Fragmentation by MS-MS of the sodiated molecule was possible using either LC/MS-MS or LC/Q-TOF-MS under positive ionization. Accurate mass measurements provided exact structural confirmation of the sodiated fragments obtained (m/z 221.0187 and m/z 238.9848). In negative ion mode, the deprotonated molecule was observed ([M - H](-) at m/z 395.0073), and fragmentation by MS-MS yielded two characteristic fragment ions (m/z 359.0306 and m/z 34.9694). Because sucralose contains three chlorine atoms, time-of-flight analyses provided a valuable amount of isotopic accurate mass information for its detection. With LC/MS-MS, the sensitivity was 10 times higher in positive ion mode than in negative ion mode, with limits of detection of 15 ng/L. Similarly, when time-of-flight mass spectrometry was used, the sensitivity was slightly better in positive ion mode, with limits of detection of 400 ng/L. Matrix effects were observed for surface and wastewater samples; thus the use of a deuterated standard (sucralose-d6) was crucial for precise quantitation. The most sensitive analytical methodology for the analysis of sucralose in water samples was LC/MS-MS using triple quadrupole under positive ion mode.

10.
Rapid Commun Mass Spectrom ; 27(17): 1891-903, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-23939955

RESUMO

RATIONALE: Imidacloprid is a potent and widely used insecticide on vegetable crops, such as onion (Allium cepa L.). Because of possible toxicity to beneficial insects, imidacloprid and several metabolites have raised safety concerns for pollenating insects, such as honey bees. Thus, imidacloprid metabolites continue to be an important subject for new methods that better understand its dissipation and fate in plants, such as onions. METHODS: One month after a single addition of imidacloprid to soil containing onion plants, imidacloprid and its metabolites were extracted from pulverized onion with a methanol/water-buffer mixture and analyzed by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS) using a labeled imidacloprid internal standard and tandem mass spectrometric (MS/MS) analysis. RESULTS: Accurate mass tools were developed and applied to detect seven new metabolites of imidacloprid with the goal to better understand its fate in onion. The accurate mass tools include: database searching, diagnostic ions, chlorine mass filters, Mass Profiler software, and manual use of metabolic analogy. The new metabolites discovered included an amine reduction product (m/z 226.0854), and its methylated analogue (m/z 240.1010), and five other metabolites, all of unknown toxicity to insects. CONCLUSIONS: The accurate mass tools were combined with LC/QTOF-MS and were able to detect both known and new metabolites of imidacloprid using fragmentation studies of both parent and labeled standards. New metabolites and their structures were inferred from these MS/MS studies with accurate mass, which makes it possible to better understand imidacloprid metabolism in onion as well as new metabolite targets for toxicity studies.


Assuntos
Imidazóis/química , Imidazóis/metabolismo , Inseticidas/química , Inseticidas/metabolismo , Espectrometria de Massas/métodos , Nitrocompostos/química , Nitrocompostos/metabolismo , Cebolas/química , Espectrometria de Massas/instrumentação , Estrutura Molecular , Neonicotinoides , Cebolas/metabolismo
11.
J Chromatogr A ; 1674: 463130, 2022 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-35605468

RESUMO

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.


Assuntos
Grafite , Humulus , Carbono , Cromatografia Líquida de Alta Pressão/métodos , Glicosídeos/análise , Humulus/química , Espectrometria de Massas , Monoterpenos/análise , Porosidade
12.
Anal Bioanal Chem ; 400(1): 101-17, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21127842

RESUMO

A library of collision-induced dissociation (CID) accurate mass spectra has been developed for efficient use of liquid chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) as a tool in systematic toxicological analysis. The mass spectra (Δm < 3 ppm) of more than 2,500 illegal and therapeutic drugs, pesticides, alkaloids, other toxic chemicals and metabolites were measured, by use of an Agilent 6530 instrument, by flow-injection of 1 ng of the pure substances in aqueous ammonium formate-formic acid-methanol, with positive and negative electrospray-ionization (ESI), selection of the protonated or deprotonated molecules [M+H](+) or [M-H](-) by the quadrupole, and collision induced dissociation (CID) with nitrogen as collision gas at CID energies of 10, 20, and 40 eV. The fragment mass spectra were controlled for structural plausibility, corrected by recalculation to the theoretical fragment masses and added to a database of accurate mass data and molecular formulas of more than 7,500 toxicologically relevant substances to form the "database and library of toxic compounds". For practical evaluation, blood and urine samples were spiked with a mixture of 33 drugs at seven concentrations between 0.5 and 500 ng mL(-1), prepared by dichloromethane extraction or protein precipitation, and analyzed by LC-QTOF-MS in data-dependent acquisition mode. Unambiguous identification by library search was possible for typical basic drugs down to 0.5-2 ng mL(-1) and for benzodiazepines down to 2-20 ng mL(-1). The efficiency of the method was also demonstrated by re-analysis of venous blood samples from 50 death cases and comparison with previous results. In conclusion, LC-QTOF-MS in data-dependent acquisition mode combined with an accurate mass database and CID spectra library seemed to be one of the most efficient tools for systematic toxicological analysis.


Assuntos
Alcaloides/análise , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Praguicidas/análise , Preparações Farmacêuticas/análise , Alcaloides/toxicidade , Humanos , Praguicidas/toxicidade
13.
J Agric Food Chem ; 69(45): 13286-13298, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34213324

RESUMO

The isomeric nature of monoterpenyl glycosides makes unambiguous identification of intact glycosides difficult. As a result, it is challenging to relate the changes in free monoterpenol concentrations to the corresponding glycosides during wine fermentation and storage. In this study, we isolated and identified linalool, nerol, and geraniol monoterpenyl glycosides fromVitis viniferacv. Riesling grapes through fractionation followed by acid or enzyme hydrolysis. Changes in the composition of identified monoterpenyl glycosides and their respective free volatiles were then monitored during alcoholic fermentations of Riesling juice with four different yeast strains across two successive years. The relative concentrations of the volatiles were monitored by solid-phase microextraction gas chromatography mass spectrometry, while ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry was used for intact glycosides. Glycoside hydrolysis during fermentation could be related to relative concentrations of the corresponding free aglycones. However, other sources of free monoterpenols were also observed. Differences in glycoside hydrolysis among yeast strains and across years were observed and may be related to grape maturity and/or nutrient levels.


Assuntos
Vitis , Vinho , Álcoois , Fermentação , Glicosídeos/análise , Monoterpenos/análise , Vinho/análise
14.
Sci Total Environ ; 770: 144661, 2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-33513501

RESUMO

Ash and surface water samples collected after wildfires in four different geographical locations (California, Colorado, Kansas and Alberta) were analyzed. The ash samples were leached with deionized water, and leachates were concentrated by solid phase extraction and analyzed by liquid chromatography/time-of-flight mass spectrometry. In addition, three surface water samples and a lysimeter water sample were collected from watersheds recently affected by fire in California and Colorado, and analyzed in similar fashion. A suite of benzene polycarboxylic acids (BPCAs), with two and three carboxyl groups and their corresponding isomers were identified for the first time in both ash leachates and water samples. Also found was a pyridine carboxylic acid (PCA), 3,5-pyridine dicarboxylic acid. Furthermore, putative identifications were made for other carboxylated aromatic acids: quinolinic, naphthalenic, and benzofuranoic acid carboxylates. The wildfire ashes, a controlled wood ash, and post-fire surface water samples suggest that burned woody material, along with surface plant-material and heated o-horizon soil organic matter, contribute to both BPCAs and PCAs in runoff. This study is the first of its kind to identify this suite of aromatic acids in wildfire ash and surface water samples. These data make an important contribution to the nature of dissolved organic matter from wildfire and are useful to better understand the impact of wildfire on water quality and drinking water sources.

15.
J AOAC Int ; 93(2): 703-11, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20480918

RESUMO

Two methods are described for identifying unknowns in complex matrixes. One approach, suitable for nonpolar and thermally stable compounds, uses GC/MS with a deconvolution technique, followed by a spectral library search. The second approach, suitable for polar and thermally labile compounds, uses LC/quadrupole-time-of-flight (LC/Q-TOF) MS with a Molecular Feature Extractor (MFE), followed by a database search on the exact mass of each found compound. Two example analyses are presented to illustrate the GC/MS method. The first example processes data files obtained by a multiresidue analysis of pesticides in surface water. In this example, 71 pesticides were identified using Deconvolution Reporting Software in conjunction with Automated Mass Spectral Deconvolution and Identification System software. The second example illustrates the deconvolution approach in detail using peaches and pears analyzed after extraction by the quick, easy, cheap, effective, rugged, and safe (QuEChERS) protocol. The LC/Q-TOF approach is illustrated through analysis of a grape extract prepared by the QuEChERS protocol. The resulting total ion chromatogram was found by the MFE to contain 510 chemicals (components). The masses of found chemicals were subsequently searched against an Exact Mass Database of hundreds pesticides, and 15 exact mass hits were found. Several of these exact mass hits were selected for further confirmation by MS/MS analysis using the same LC/Q-TOF.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Praguicidas/análise , Automação , Cromatografia Gasosa/métodos , Cromatografia por Troca Iônica/métodos , Cromatografia Líquida/métodos , Análise de Alimentos/métodos , Contaminação de Alimentos , Frutas/metabolismo , Software , Temperatura , Fatores de Tempo , Água/análise , Poluentes Químicos da Água/análise
16.
J Agric Food Chem ; 68(12): 3817-3833, 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32129620

RESUMO

Ultra-high-performance liquid chromatography (UHPLC) accurate mass tandem mass spectrometry is a powerful tool for identifying and profiling plant metabolites. Here, we describe an approach to characterize glycosidically bound precursors of monoterpenoids, norisoprenoids, volatile phenols, aliphatic alcohols, and sesquiterpenoids in grapes. Chromatographic separation of glycosylated compounds was evaluated using phenyl-hexyl (reverse phase), glycan/hydrophilic interaction, and porous graphitic carbon (PGC) stationary phases. PGC provided the best UHPLC separation for 102 tentatively identified aroma precursors in Vitis vinifera L. cv. Riesling and Muscat of Alexandria berries. Monoterpene-triol, monoterpene-tetraol, and sesquiterpenol glycosides were tentatively identified for the first time in grapes, and a C6-alcohol trisaccharide was tentatively identified for the first time in any plant. Comparison of glycosylated aroma molecules in Riesling and Muscat of Alexandria grapes showed that the two varieties were distinguishable based on relative abundances of shared glycosides and the presence of glycosides unique to a single variety.


Assuntos
Frutas/química , Glicosídeos/análise , Vitis/química , Vinho/análise , Cromatografia Líquida de Alta Pressão , Monoterpenos/análise , Norisoprenoides/análise , Odorantes/análise , Sesquiterpenos/análise , Espectrometria de Massas em Tandem
17.
J Am Soc Mass Spectrom ; 31(6): 1189-1204, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32356661

RESUMO

A rapid screening method for the detection of nontargeted compounds in surface water samples was developed using MS-MS high-resolution mass spectrometry and data-dependent acquisition. The key parameters for the acquisition method were optimized using five model compounds with diverse chemical characteristics. The parameter selection required optimization between the total number of precursor ions that could be selected in an LC-MS run, the quality of each MS (full range) spectrum, and the quality of each MS-MS fragmentation spectrum. After the acquisition method was optimized, 18 surface water samples from rivers, reservoirs, and effluents from wastewater treatment plants were analyzed, generating 41625 MS-MS spectra in about 14 h. The raw data were then converted into two generic formats using the open-access program MSConvert. A combinatorial approach, similar partition searching (SPS), was then used to putatively identify analytes from the accurate mass of each analyte (adjusted for the adduct mass) and the corresponding MS-MS spectra were obtained. In this approach, the structures of about 250000 common compounds, stored in a large database as mathematical partitions of their exact mass, were compared directly to each MS-MS spectrum. Compounds with a similar mass and retention time were grouped together and labeled as "Analytes", using an Excel Add-In. The isotope ratio data from the MS spectrum, the corresponding MS-MS spectra, and the putative identifications were then imported into an Access relational database to facilitate sorting, searching, filtering, and querying the results. This allowed final inspection to assess confidence of the identifications made through the nontargeted screening.

18.
Food Chem ; 297: 124921, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253264

RESUMO

Plants conjugate monoterpenoids to sugars, rendering them non-volatile. Hydrolysis of these glycosidic precursors frees the volatile aroma compounds. Here, we profile intact monoterpenyl glycosides in six Vitis vinifera grape berry cultivars. Relative concentrations of twenty-six monoterpenyl glycosides, including nine new putatively identified compounds, were analyzed by UHPLC-QTOF MS/MS at three times during grape maturation (pre-véraison, véraison, and post-véraison). Total glycoside content reached a maximum in Muscat cultivars post-véraison but remained relatively constant in all other cultivars. Three types of monoterpenyl glycosides predominated in all samples: malonylated monoterpenol glucosides, monoterpenol hexose-pentoses, and monoterpendiol hexose-pentoses. The two Muscat cultivars were not differentiated at the earlier developmental stages but could be differentiated post-véraison. In contrast, similarities between Chardonnay and Pinot noir glycoside profiles developed post-véraison. Overall monoterpene glycoconjugation patterns may align with underlying genetic relationships among cultivars. By understanding monoterpene glycoconjugation in wine grapes, scientists and winemakers can better understand grape and wine aromas.


Assuntos
Monoterpenos/química , Vitis/química , Cromatografia Líquida de Alta Pressão , Análise por Conglomerados , Frutas/química , Frutas/metabolismo , Glicosídeos/química , Glicosídeos/metabolismo , Glicosilação , Monoterpenos/metabolismo , Análise de Componente Principal , Espectrometria de Massas em Tandem , Vitis/metabolismo
19.
J Food Drug Anal ; 27(3): 679-691, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31324284

RESUMO

The targeted analysis of veterinary drug residues in honey traditionally involves a series of extraction and purification steps prior to quantification with high performance liquid chromatography coupled to high resolution or tandem mass spectrometry. These steps, designed to separate the target analytes from interferences, are generally time-consuming and costly. In addition, traditional cleanup steps are likely to eliminate other compounds whose analysis could prove decisive in current or future assessment of the honey sample. Alternatively, direct injection without complex sample preparation steps has been introduced for the fast analysis of trace compounds in environmental and food matrices. The aim of this study was to develop a rapid method for the targeted analysis of 7 key veterinary drug residues in honey based on direct injection high performance liquid chromatography coupled to quadrupole time-of-flight, while simultaneously recording data-independent MS/MS (e.g. All Ions MS/MS data) for future re-examination of the data for other purposes. The new method allowed for the detection of the target residues at levels approximately 20-100 times lower than current regulatory limits, for a total analysis time of about 45 min. The recoveries (103-119%), the linearity (R ≥ 0.996) and the repeatability (RSD ≤ 7%) were satisfactory. The method was then applied to 35 honey samples from the Canadian market. Residues of tylosin A, tylosin B, sulfamethazine and sulfadimethoxine were detected in 6, 9, 6 and 23% of the samples respectively, at levels below the regulatory limits in Canada. The possibility of adding a hydrolysis step to study sulfonamides in honey was tested, which provided good results for this family of compounds but lead to degradation of some of the other analytes. Finally, the non-targeted identification of several compounds was demonstrated as a proof of concept of future re-examination of All Ions MS/MS data. This paper illustrates the capacity of this novel method to combine targeted and non-targeted screening of chemical residues in honey.


Assuntos
Antibacterianos/análise , Mel/análise , Cromatografia Líquida de Alta Pressão , Avaliação Pré-Clínica de Medicamentos , Espectrometria de Massas
20.
J Agric Food Chem ; 67(9): 2647-2659, 2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30758205

RESUMO

Sangiovese is the most widespread Italian red cultivar and constitutes the basis of internationally known wines such as Chianti and Brunello di Montalcino. Outside of Europe, Argentina is the largest producer, followed by the United States. This study sought to define and compare 2016 vintage Sangiovese wine composition from various production regions in California and Italy. Forty-six commercial Sangiovese wines from California and Italy were analyzed for volatile profile, color, phenolic, and elemental content. This study demonstrates that it is possible to determine regional differences among wines based on these chemical profiles. However, some Californian and Italian wine had similar chemical compositions. In order to compare Californian and Italian wines, Californian wine reference models were developed using the chemical parameters from Sangiovese wines, performing a Soft Independent Modeling of Class Analogy (SIMCA). To our knowledge, this is the first time that an extensive regionality study has been attempted for Sangiovese wines.


Assuntos
Frutas/química , Vitis/química , Vinho/análise , Argentina , California , Cromatografia Gasosa-Espectrometria de Massas , Itália , Metais/análise , Polifenóis/análise , Compostos Orgânicos Voláteis/análise , Vinho/classificação
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