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1.
Bol. latinoam. Caribe plantas med. aromát ; 18(5): 492-503, sept. 2019. tab, ilus
Artigo em Inglês | LILACS | ID: biblio-1008286

RESUMO

The aim of the present work was to optimize the main experimental variables of a procedure using HS-SPME/GC-MS as the analytical methodology to establish the profile of the volatile compounds present in aerial parts of Hedeoma multiflorum Benth. The influence of the type of fiber, equilibrium time, extraction time and extraction temperature on the composition of the volatile compounds was determined using response surface methodology (RSM), and the parameters of the models were corroborated by multiple linear regressions. The results showed that the regression models generated adequately explained the data variation and represented the relationships between the parameters and their responses. The optimal analysis conditions from the contour plots were established (DVB/CAR/PDMS fiber, with a 10 min equilibrium time, 10 min extraction time, and 40°C). Under these conditions, 41 volatile components in the whole plant were determined, which represents more than those reported using hydrodistillation.


El objetivo del presente trabajo fue optimizar las principales variables experimentales de un procedimiento HS-SPME/GC para establecer el perfil de compuestos volátiles presentes en la parte aérea de Hedeoma multiflorum Benth. Se determinó la influencia de las variables tipo de fibra, tiempo de equilibrio, tiempo de extracción y temperatura de extracción sobre la composición de los volátiles, utilizando una met odología de superficie de respuesta (RSM) y los parámetros del modelo se corroboraron por regresión lineal múltiple. Los resultados demostraron que los modelos de regresión generados explican adecuadamente la variación de los datos y representaron significativamente las relaciones reales entre los parámetros y sus respuestas. Las condiciones óptimas de análisis fueron establecidas (DVB/CAR/PDMS, con un tiempo de equilibrio de 10 minutos, un tiempo de extracción de 10 minutos y trabajando a 40°C). Utilizando esta metodología, se determinaron 41 componentes volátiles en planta entera, más que los reportados mediante hidrodestilación.


Assuntos
Hedeoma , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/química , Cromatografia Gasosa-Espectrometria de Massas/métodos
2.
Food Chem ; 300: 125200, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31325748

RESUMO

Ethyl carbamate (EC) and N-nitrosoamines (NAs) are toxic contaminants which can be typically formed in fermented alcoholic beverages. In the present work, a novel approach for simultaneous analysis of EC and NAs in beer and yellow rice wine based on ice-bath assisted sodiumhydroxide purification and GC-MS/MS was firstly established. Samples were extracted with acetonitrile-ethyl acetate after addition of internal standards. The extraction solution system was purified by sodiumhydroxide solid under ice-bath. After concentration, target analytes were separated on a HP-INNOWAX quartz capillary column and determined under dynamic multiple reactions monitoring mode of MS/MS. The limits of detection and quantification (LOD and LOQ), matrix effect, recovery and precision of the method were evaluated. Results were linear in the concentration range 2-200 µg/L for all analytes of interest, with regression coefficients higher than 0.999. LODs and LOQs were in the ranges of 0.1-0.5 µg/kg and 0.5-1.5 µg/kg, respectively. The mean recoveries at three spiked levels were between 81.5% and 121.0%. The intra- and inter-day precisions were in the ranges of 2.2-9.4% and 1.6-7.9%, respectively. The validated method was successfully applied to determine thirteen targets in commercial beer and yellow rice wine. EC was detected in all beers and yellow rice wines with the concentrations ranging from 1.18 to 22.90 µg/L. Results indicated wide EC contamination and confirmed its urgency for monitoring EC in fermented alcoholic beverages.


Assuntos
Cerveja/análise , Contaminação de Alimentos/análise , Nitrosaminas/análise , Uretana/análise , Vinho/análise , Acetonitrilos/química , Fracionamento Químico/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Gelo , Limite de Detecção , Oryza , Reprodutibilidade dos Testes , Hidróxido de Sódio/química , Espectrometria de Massas em Tandem/métodos
3.
Food Chem ; 298: 125003, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260957

RESUMO

The oral breakdown, sensory properties, and volatile release during mastication of white bread were investigated. The results of correlation analysis for white bread's physical properties and it's oral physiological parameters during chewing have elucidated that bread's physical properties determined the oral processing behavior. During chewing of white bread, 15 dominant ions with regularly changing patterns were monitored by proton transfer reaction-mass spectrometry (PTR-MS). These dominant ions derived from 32 volatile compounds were further confirmed by pure standards. Partial least squares regression (PLSR) analysis was used to explore the positive correlations between the sensory analysis and the dominant aroma compounds. Results have shown that 9 aroma compounds were predicted as the potent odorants contributing to the changes in aroma profiles. Finally, 3-hydroxy-2-butanone, 2-methyl-1-propanol, and heptanoic acid were confirmed as the key aroma compounds contributing to the changes in aroma profiles of white bread before and after chewing.


Assuntos
Pão , Mastigação , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Acetoína/análise , Adulto , Pão/análise , Butanóis/análise , Feminino , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cromatografia Gasosa-Espectrometria de Massas/estatística & dados numéricos , Ácidos Heptanoicos/análise , Humanos , Análise dos Mínimos Quadrados , Masculino , Espectrometria de Massas/métodos , Espectrometria de Massas/estatística & dados numéricos , Saliva/química , Microextração em Fase Sólida/métodos , Paladar , Triticum/química
4.
Food Chem ; 298: 125050, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260955

RESUMO

An analytical method involving QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation, followed by LC-MS/MS and GC-MS/MS was developed and validated for the determination of 60 pesticides in eggs. Recoveries of 70-120% were achieved for selected pesticides and relative standard deviations <20% were obtained for most analytes at three concentrations. The limit of quantification was <10 µg kg-1 for 83% of the total pesticides. This method was used to analyze 58 egg samples and the residues of seven pesticides (disulfoton, fipronil sulfone, cyromazine, o,p-DDT, p,p-DDD, p,p-DDT, and permethrin) were quantified in 16 egg samples at levels of 5-10 µg kg-1, which was below the corresponding the maximum residue levels, as established by Korean Ministry of Food and Drug Safety. We demonstrated that LC-MS/MS and GC-MS/MS in combination with QuEChERS can be used to routinely monitor multiple pesticide residues in egg samples.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Animais , Galinhas , Cromatografia Líquida de Alta Pressão , Dissulfóton/análise , Ovos/análise , Feminino , Limite de Detecção , Pirazóis/análise , Reprodutibilidade dos Testes
5.
J Agric Food Chem ; 67(32): 9112-9120, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31314506

RESUMO

A reliable and robust tool for supporting the panel test in virgin olive oil classification is still required. We propose four chemometric approaches based on t test, principal component analysis (PCA) and linear discriminant analysis (LDA), applied for combining sensorial data, and chemical measurements. The former was from the panel test, and the latter was from headspace solid-phase microextraction-gas chromatography-mass spectrometry quantitation of 73 volatile organic compounds (VOCs) of 1223 typical commercial virgin olive oils, with most of them recognized as difficult to classify with accuracy by the panel test. The approaches were developed and validated, and the best results, with 83.5% correct classification, were using the PCA-LDA approach. Among the other methods, developed for proposing simplified procedures based on a smaller number of VOCs, the best method gave 80.1% correct classification only using 10 VOCs. All of the approaches suggested that octane, heptanal, pent-1-en-3-ol, Z-3-hexenal, nonanal, and 4-ethylphenol should be considered as a basis of volatiles for classification of olive oil samples.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Azeite de Oliva/química , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Análise Discriminante , Humanos , Olea/química , Azeite de Oliva/classificação , Análise de Componente Principal , Paladar
6.
J Chem Ecol ; 45(7): 579-587, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31256322

RESUMO

Domestic cats (Felis silvestris catus) are solitary and territorial, and mark their territories by spraying urine, which emits a strong odor produced by volatile organic compounds (VOCs). Previous studies have focused on identifications of specific VOCs, such as 3-mercpto-3-methyl-1-butanol, a cat-specific VOCs. However, little is known about how whole volatile profiles of their sprayed urine change over time or how the profiles differ among individuals. This study investigated temporal changes and individual differences of volatile profiles produced by whole VOCs in cat urine, and the ability of cats to discriminate between these scent differences. Volatile profiles of fresh and aged cat urine were analyzed by using two-dimensional gas chromatography-mass spectrometry with a VOC preconcentrator comprehensively. Volatile profiles produced by hundreds of VOCs emitted from cat urine were influenced primarily by the age of the urine, and secondarily by individuality. During habituation-dishabituation tests, subjects discriminated between fresh and 24 h-old samples of same individuals, and between odor of different individuals from 0 h-, 3 h-old, and 24 h-old samples. These results strongly suggest that cats can recognize conspecific individuals via olfaction. Since most VOCs varied among individuals but were not stable over time, their urine may contain unknown VOCs that vary among individuals, are stable over time, and act as individual recognition signals.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos Voláteis/urina , Animais , Comportamento Animal , Gatos , Análise Discriminante , Masculino , Análise de Componente Principal , Fatores de Tempo , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação
7.
Food Chem ; 298: 125088, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260987

RESUMO

Infant formula certified reference material (CRM, KRISS CRM 108-02-003) were developed for the analysis of organic nutrients. The CRM is a milk-based infant formula powder, packaged at 14 g per unit. Ten thousand units were prepared and stored at -70 °C. For the certification of each nutrient, ten units were analyzed for simultaneous value-assignment and homogeneity test. Analytical methods used were isotope dilution mass spectrometry (IDMS) based on liquid chromatography mass spectrometer (LC/MS) or gas chromatography mass spectrometer (GC/MS) as higher-order reference methods.13 vitamins, 3 fatty acids, and total cholesterol were certified. The between-unit relative standard deviation of measurement results for each nutrient ranged 0.2% to 2.5%, showing very good homogeneity. The expanded relative uncertainties of the certified values ranged from 1% to 8%, indicating that they have higher-order metrological quality. The values of proximates (proteins, lipids, carbohydrates, water, and ash) were assigned through inter-laboratory comparisons.


Assuntos
Análise de Alimentos/métodos , Fórmulas Infantis/análise , Fórmulas Infantis/normas , Certificação , Colesterol/análise , Cromatografia Líquida/métodos , Ácidos Graxos/análise , Análise de Alimentos/normas , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Lactente , Nutrientes/análise , Padrões de Referência , Vitaminas/análise
8.
J Chromatogr A ; 1602: 450-457, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31208794

RESUMO

The analysis of wastewater for the determination of human biomarkers of exposure (human metabolites) is a non-intrusive, economic and complementary alternative to the analysis of urine in the monitoring of human exposure to chemicals of concern. This study provides the first gas chromatography-based method for the determination of three metabolites of chlorinated organophosphorous flame retardants (OPFRs: bis(2-chloroethyl) phosphate, bis(chloropropyl) phosphate and bis(1,3-dichloro-2-propyl) phosphate) in wastewater. A solid-phase extraction procedure based on the use of mixed-mode reversed-phase weak anion exchange sorbents was optimized including a fractionated elution of OPFRs and their metabolites. Analytes derivatization was investigated by comparing two silylating reagents, N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide and N-methyl-N-(trimethylsilyl)trifluoroacetamide, the first one providing better results. Determination was performed by gas chromatography-high resolution mass spectrometry with a quadrupole-time-of-flight system (GC-QTOF) in order to improve selectivity. Furthermore, the use of GC-QTOF combined with the specific ion obtained from silylated metabolites (m/z 154.9924) can be exploited to screen for other phosphate ester metabolites. Under final conditions, the overall method performance was satisfactory, affording method detection limits ranging from 1.1 to 4.6 ng/L, percentages of recovery from 90% to 110%, and relative standard deviations below 13%. The analysis of composite raw wastewater samples collected over 24 h in the NW of Spain allowed to quantify, for the first time in this matrix, the metabolite bis(chloropropyl) phosphate at levels over 60 ng/L.


Assuntos
Acetamidas/química , Retardadores de Chama/análise , Fluoracetatos/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Halogenação , Metaboloma , Compostos de Organossilício/química , Fósforo/análise , Águas Residuárias/química , Humanos , Limite de Detecção , Organofosfatos/análise , Padrões de Referência , Extração em Fase Sólida
9.
J Chromatogr A ; 1602: 441-449, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31230877

RESUMO

Seven phthalate esters (di-isobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP)) were analyzed by pyrolyzer/thermal desorption-gas chromatography/mass spectrometry (Py/TD-GC/MS), the retention index and relative response factor (RRF) relative to DEHP was calculated for each compound and used to construct a quantitative database (qDB). This qDB enables normalization of the retention time and response factor of each phthalate ester between any laboratory simply by analyzing an n-alkane solution and DEHP standard material. This allows for easy calculation of the phthalate ester content of samples without preparation of calibration curves. The efficacy of this qDB method was verified by performing a quantitative analysis of phthalate esters at 4 different laboratories that showed actual retention times were within ±0.012 min of the estimated retention times for all compounds at all laboratories. Similarly, the mean recovery rate (n = 6) at each laboratory was within 79-113%. Quantitative analysis was also performed on 30 real samples using both the qDB method and the Py/TD-GC/MS method set forth in IEC62321-8, which involves the preparation of 1-point calibrations to perform quantitative analysis. The difference in quantitative results between the methods was approximately within ±200 mg/kg for compounds in the concentration region of <2000 mg/kg.


Assuntos
Bases de Dados de Compostos Químicos , Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ácidos Ftálicos/análise , Polímeros/química , Fatores de Tempo
10.
Anal Chim Acta ; 1075: 38-48, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31196422

RESUMO

Gas chromatography inductively coupled plasma triple quadrupole mass spectrometry (GC-ICP-MS/MS) operated in N2O reaction mode (mass-shift mode) was established for the analysis of six congeners of polybrominated diphenyl ethers (PBDEs): BDE 28, BDE 47, BDE 99, BDE 100, BDE 153 and BDE 154 in fish samples. The spectral interference on the determination of PBDEs was eliminated by measuring the product ion (BrO+) instead of traditional methods measuring Br+. After comparing the signal intensities of the three reaction gases (O2, H2, and N2O), the highest sensitivity was found using N2O as the reaction gas. The results showed that bromine is an element that suffers from strong spectral overlap in ICP, mainly from Ar-based polyatomic interferences. Spectral interference was assessed by measuring the bromine isotope ratio of 81Br+ and 79Br+ of the six priority PBDEs in the He collision mode and N2O reaction mode, respectively. In the conventional He collision mode, the relative isotope ratio of 79Br/81Br (the measured isotope ratio to the natural isotope ratio) of the analytes ranged from 0.955 to 0.965, which proves that using He as the collision gas cannot completely eliminate the spectral interference. In the N2O reaction mode, the relative isotope ratio of 79Br/81Br ranged from 0.991 to 1.004, demonstrating that spectral interference can be fully eliminated. Samples were processed using the modified QuEChERs method with detection limits ranging from 0.03 to 0.09 ng g-1 with a relative standard deviation of less than 3%. Six priority PBDEs in the NIST reference materials SRM 1947 (frozen fish tissue homogenate) were determined by mass-shift mode to verify this conclusion. No statistically significant difference was observed between the measured value and the certified value, with recoveries between 95% and 114%. The method was applied to the analysis of PBDEs in marine fish samples and five PBDEs were observed (BDE28,BDE-47, BDE-99, BDE-100 and BDE-153) at concentrations ranging from 0.04 to 0.54 ng g-1.


Assuntos
Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Animais , Peixes , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limite de Detecção , Espectrometria de Massas em Tandem/métodos
11.
Planta Med ; 85(11-12): 941-946, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31163460

RESUMO

Targeted isolation based on a combination of NMR and HPLC-PDA-MS of a dichloromethane extract of Thymus vulgaris Varico 3 aerial parts afforded one new p-cymene dimer, 6,3',4'-trihydroxy-5,5'-diisopropyl-2,2'-dimethylbiphenyl (1: ), together with two known p-cymene derivatives (2: and 3: ), as well as five known compounds, namely, thymol (4: ), oleanolic acid (5: ), ursolic acid (6: ), cirsimaritin (7: ), and xanthomicrol (8: ). The structural elucidation of all compounds was performed by spectroscopic analyses, including 1D and 2D NMR, and HRESIMS experiments. The biphenyls were assayed for their inhibitory activity on tyrosinase. Compounds 2: and 3: showed negligible activity on tyrosinase, while compound 1: effectively inhibited the enzyme with 35% (± 0.3) inhibitory activity, higher than the inhibition of the reference compound kojic acid (18.6 ± 0.02).


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectroscopia de Ressonância Magnética/métodos , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monoterpenos/isolamento & purificação , Extratos Vegetais/química , Thymus (Planta)/química , Flavonas/farmacologia , Monoterpenos/farmacologia , Ácido Oleanólico/farmacologia , Timol/farmacologia , Triterpenos/farmacologia
12.
Food Chem ; 297: 124850, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253256

RESUMO

This study investigated discrimination and prediction of ochratoxin A (OTA) in three Aspergillus carbonarius strains cultured grape-based medium using E-nose technology and GC-MS analysis. Results showed that these strains cultured medium samples were divided into four groups regarding their log 10 OTA value using an equispaced normal distribution analysis. Partial least squares-discriminant analysis (PLS-DA) revealed that GC-MS PLS-DA model only separated the low OTA level medium samples from the rest OTA level samples, whereas all the OTA level samples were segregated from each other using E-nose PLS-DA model. Partial least squares regression (PLSR) analysis indicated that an excellent prediction performance was established on the accumulation of OTA in these medium samples using E-nose PLSR, whereas GC-MS PLSR model showed a screening performance on the OTA formation. These indicated that E-nose analysis could be a reliable method on discriminating and predicting OTA in A. carbonarius strains under grape-based medium.


Assuntos
Aspergillus/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ocratoxinas/análise , Vitis/metabolismo , Aspergillus/genética , Aspergillus/crescimento & desenvolvimento , Análise Discriminante , Nariz Eletrônico , Análise dos Mínimos Quadrados , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química
13.
Anal Bioanal Chem ; 411(21): 5423-5436, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31161326

RESUMO

It is necessary to characterize and classify neural stem cells (NSCs) and differentiated cells (DCs) for potential use of NSC to treat neurodegenerative diseases. We therefore performed an analysis of NSCs and DCs using gas chromatography mass spectrometry (GC-MS) and direct infusion mass spectrometry (DI-MS) with elaborate multivariate statistical analysis for the characterization and classification of rat NSCs and DCs. GC-MS and DI-MS detected a total of 92 metabolites and lipids in NSCs and DCs, and the levels of 72 of them differed significantly between NSCs and DCs. The optimal model for partial least squares (PLS) discriminant analysis was constructed by applying 3 and 2 PLS components with a unit-variance scaling method for classifying NSCs and DCs based on the data obtained in the GC-MS and DI-MS analyses, respectively. The obtained results from PCA and PLS-DA suggest that creatinine, lactic acid, lysine, glutamine, glycine, pyroglutamic acid, PG 18:1/20:2, PS 18:0/20:2, PI 18:0/20:3, PC 16:0/20:4, PI 16:0/20:4, and PI 18:1/20:4 were the main contributors that provided distinct characteristics of NSCs and DCs. The results of this study suggest objective and complementary criteria for the characterization and classification of NSCs and DCs for potential clinical applications. Graphical abstract.


Assuntos
Diferenciação Celular , Metabolismo dos Lipídeos , Células-Tronco Neurais/classificação , Células-Tronco Neurais/citologia , Animais , Células Cultivadas , Análise Discriminante , Cromatografia Gasosa-Espectrometria de Massas/métodos , Análise dos Mínimos Quadrados , Espectrometria de Massas/métodos , Análise de Componente Principal , Ratos , Ratos Sprague-Dawley
14.
Anal Bioanal Chem ; 411(20): 5013-5021, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31222408

RESUMO

Neonicotinoids (NEOs) and synthetic pyrethroids (PYRs) are active ingredients of commercial pesticides and/or insecticides with extensive indoor and outdoor applications, worldwide. Improved exposure metrics are warranted for NEOs and PYRs, if we are to better understand their human health effects. A cohort-friendly protocol for determining non-specific biomarkers of exposure to NEOs and PYRs, e.g. 6-chloronicotinic acid (6-CN) and 3-phenoxybenzoic acid (3-PBA), respectively, in human urine voids was proposed. A series of optimization experiments were conducted to validate the bioanalytical protocol using gas chromatography coupled with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) in MRM mode. The method reached low detection limits for both analytes (0.075 µg L-1 for 6-CN and 0.050 µg L-1 for 3-PBA) in a short preparation and analysis time. The method used small initial urine sample volume (2 mL), short extraction time (≈ 240 min for the batches of 32 samples) and instrumental analysis time (≈ 14 min) for both pesticide metabolites in a single run. This protocol could facilitate the assessment of population exposure metrics for these pesticides and their inclusion in health risk assessment. Graphical abstract.


Assuntos
Exposição Ambiental , Cromatografia Gasosa-Espectrometria de Massas/métodos , Neonicotinoides/urina , Praguicidas/urina , Piretrinas/urina , Biomarcadores/urina , Estudos de Coortes , Monitoramento Ambiental/métodos , Humanos , Limite de Detecção , Neonicotinoides/normas , Praguicidas/normas , Piretrinas/normas , Padrões de Referência
15.
Food Chem ; 297: 124998, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253278

RESUMO

The analysis of free fatty acids (FFAs) in edible oils can provide important information for quality control and oil authentication. Herein, we report the comprehensive profiling of FFAs in edible oils via magnetic dispersive extraction combined with comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS). A magnetic extractant was designed for dispersive extraction of FFAs. The extraction conditions were carefully optimized. To assess the extraction method, we first use the method for analysis of 7 targeted FFAs. The limits of detection range from 5.6 to 25.8 ng g-1, and the recoveries in oil samples are 81%-107%. We then performed comprehensive profiling of untargeted FFAs in oil by combining the extraction method with GC × GC-MS. A total of 64 FFAs were identified positively or putatively. The proposed method can provide FFA fingerprint data to guide the processing, storage and authentication of edible oils.


Assuntos
Ácidos Graxos não Esterificados/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Magnetismo , Óleos Vegetais/química , Amônia/química , Ácidos Graxos não Esterificados/isolamento & purificação , Óxido Ferroso-Férrico/química , Metanol/química , Dióxido de Silício/química
16.
Food Chem ; 297: 124959, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253273

RESUMO

Volatile sulfur-containing compounds (VSCs) often exist at extremely low concentrations, making them difficult to be determined. The VSCs in Laobaigan (LBG) Baijiu were analyzed by headspace solid-phase microextraction (HS-SPME) coupled with GC × GC-SCD, by which 12 VSCs were identified. Among the 65 odor-active compounds that were determined by GC-O with the aid of aroma extract dilution analysis (AEDA), benzenemethanethiol and 2-methyl-3-furanthiol were found to possess the highest FD values of 6561. The limits of detection (LODs) of the identified VSCs determined by GC × GC-SCD were found to be extremely low at 0.05-1.53 ng/L, with their analytical recoveries from 85% to 116%. The VSCs in the LBG samples were determined in a range of concentrations from 0.77 ±â€¯0.02 µg/L to 60.04 ±â€¯2.32 µg/L. Benzenemethanethiol, dimethyl trisulfide, 2-methyl-3-furanthiol and 2-furfurylthiol exhibited odor activity values (OAVs) > 100 and significantly contributed to the overall aroma of LBG Baijiu.


Assuntos
Bebidas Alcoólicas/análise , Análise de Alimentos/métodos , Odorantes/análise , Enxofre/análise , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa/métodos , Furanos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limite de Detecção , Luminescência , Olfatometria/métodos , Microextração em Fase Sólida/métodos , Compostos de Sulfidrila/análise , Compostos de Enxofre/análise , Compostos Orgânicos Voláteis/química
17.
Food Chem ; 297: 124948, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253280

RESUMO

Djulis (Chenopodiun formosaneum Koidz.,), pseudo-cereal crop emerged as a potential source of functional ingredients, was used to identify phytosterols and triterpenes from seven inbred lines of Djulis hull using GC-MS. Key bioactive compounds were identified including 6 phytosterols (34.73-59.48 mg/100 g), 6 triterpenes (30.56-57.47 mg/100 g), and 5 other unsaponifiable compounds (15.89-22.50 mg/100 g). Moreover, principal component analysis (PCA) was conducted and explored the variation among Djulis hull samples with two clusters based on the surface color that reflected the content of phytosterols and triterpenes. These results confirmed that the color might be used as an indicator for estimation of phytosterol and triterpene contents in Djulis hull. Overall, this is the first study that identified novel unsaponifiable compounds in Djulis hull, which might contribute to the development of phytosterols and/or triterpenes enriched functional foods.


Assuntos
Chenopodium/química , Fitosteróis/análise , Triterpenos/análise , Análise de Alimentos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cromatografia Gasosa-Espectrometria de Massas/estatística & dados numéricos , Pigmentação , Análise de Componente Principal
18.
Food Chem ; 297: 124961, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253315

RESUMO

In this work, three versions of the QuEChERS method (original, AOAC 2007.01 and CEN 15662) were evaluated for the extraction of 38 multiclass pesticides from a mixture of five dried fruits: (strawberry, blackberry, passion fruit, pineapple and grapes) prior to their gas chromatography tandem mass spectrometry analysis. Among them, the AOAC 2007.01 method provided the best results in terms of lower amount of matrix co-extractives, matrix effect, extraction efficiency and precision. Its application to the analysis of the same pesticides in the individual dried fruits provided good recovery (between 70 and 120%) and relative standard deviation values (<20%) for most pesticides at three spiked levels. Matrix effect assessment revealed the necessity of taking into account such effect. Matrix-matched calibration data were also satisfactory for all analytes and matrices being the R2 ≥ 0.9900 and the lowest calibration level 5 µg/kg, which is lower than the agreed limit set at 10 µg/kg for monitoring purposes in food applications. Three samples of each type were also analysed, finding residues of metalaxyl, chlorpyrifos and iprodione in some of them.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Praguicidas/análise , Calibragem , Fracionamento Químico/métodos , Praguicidas/isolamento & purificação , Espectrometria de Massas em Tandem/métodos
19.
Forensic Sci Int ; 301: 447-454, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31153676

RESUMO

This work has shown that it is a valid method for determining ketamine, norketamine and amphetamines derivates in hair samples of forensic cases. This method was validated meeting the criteria of sensitivity and accuracy for detecting repeated consumption of ketamine in hair samples of forensic interest, according to the proposed cut-off for ketamine of 0.5 ng/mg. The detection of norketamine allowed discriminating between active uses and external contamination. The assessed method was applied for analyzing 1189 hair samples of judicial interest received in the INTCF along 15 months, obtaining 62 positive in ketamine consumption. This means a 5.2% of positivity. Ketamine consumers present a profile of young age (21-30 years old), polydrug use with consumption of synthetic substances preferably MDMA and, then, amphetamine. As consumer is collective, prone to consume new psychoactive substances, requires special attention due to they show a consumer profile with higher prevalence in MDMA than amphetamine, indicating that ketamine consumers belong to a subgroup with a different profile within the INTCF casuistry. The results of the exercises of the proficiency tests performed satisfactorily in all cases. In conclusion, it is a suitable method also to evaluate the chronic consumption of ketamine, in addition to amphetamines in the same method of analysis.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Cabelo/química , Ketamina/análogos & derivados , Ketamina/análise , Detecção do Abuso de Substâncias/métodos , Adulto , Anestésicos Dissociativos/análise , Humanos , Limite de Detecção , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Adulto Jovem
20.
Environ Monit Assess ; 191(7): 411, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31165936

RESUMO

Industrial wastewater could be an important source for the emission of volatile (VOCs) and semi-volatile organic compounds (SVOCs), but little is known about it. In this study, a method for the identification and quantitation of 43 VOCs and SVOCs in coking wastewater was developed using a solvent-free equilibrium extraction method on the basis of headspace solid-phase microextraction accompanied by gas chromatography-triple quadrupole tandem mass spectrometry (HS-SPME-GC-MS/MS). To ensure good extraction efficiency, the parameters that have an effect on the HS-SPME-GC-MS/MS process were carefully optimized, in terms of fiber exposure time and temperature, pH, salt additives, sample volume, and desorption time. The HS-SPME method showed good linearity range with coefficients of determination (R2) ≥ 0.991 and achieving a satisfactory recoveries value (70-120%) with good relative standard deviations (RSDs) < 20% (precision). Furthermore, the purposed approach proved to be sensitive with low detection limits, where the values ranged from 0.03 to 3.01 µg/L. The real sample analysis result showed that 43 of VOCs and SVOCs were detected in raw coking wastewater, with 3-cresol as the dominant ones. Further, the method revealed that seven phenols, 11 polycyclic aromatic hydrocarbons, and five BTEX were detected even in the treated effluent. In conclusion, the HS-SPME method developed in this study is simple in sample preparation, convenient, sensitive, and could satisfy the requirement of the analysis of VOCs and SVOCs in coking wastewater.


Assuntos
Monitoramento Ambiental/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Compostos Orgânicos Voláteis/análise , Águas Residuárias/química , Coque , Limite de Detecção , Solventes/análise
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