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1.
Chemosphere ; 258: 127367, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947676

RESUMO

Due to their important roles in salt-producing acid-base reactions, new particle formation (NPF), and as precursors in secondary organic aerosol (SOA) producing reactions, the atmospheric concentrations of particulate volatile amines (dimethylamine (DMA), ethylamine, diethylamine (DEA), propylamine, and butylamine) at Seoul were analyzed and evaluated. To quantify the presence of volatile amines in particulate matter with aerodynamic diameters less than or equal to a nominal 2.5 µm (PM2.5), an efficient and rapid analytical method based on in-matrix ethyl chloroformate (ECF) derivatization followed by headspace solid-phase microextraction (HS-SPME) was developed and validated using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) in the multiple reaction monitoring (MRM) mode. The annual mean concentration of the total 5 target amines was 5.56±2.76 ng/m3 and the seasonal difference was small. The concentrations of particulate amines measured in this study were lower than those observed in Zongludak, Turkey, Nanjing, China, and Jeju, Korea but slightly higher than that reported in Kobe, Japan. The concentrations of the nitrosamines (nitrosodimethylamine (NDMA) and nitrosodiethylamine (NDEA)), and of the nitramines (dimethylnitramine (DMN) and diethylnitramine (DEN)) measured along with those of the target amines were used in a simple linear regression analysis. It indicates the contribution of DMA to the formation of NDMA in all seasons (except the fall) and DEA to the formation of NDEA in the summer, while DMA and DEA did not significantly contribute to the formation of nitramines.


Assuntos
Poluentes Atmosféricos/análise , Aminas/análise , Monitoramento Ambiental , China , Dietilnitrosamina , Dimetilaminas , Dimetilnitrosamina/análise , Etilaminas , Cromatografia Gasosa-Espectrometria de Massas/métodos , Nitrosaminas/análise , Material Particulado/análise , República da Coreia , Seul , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem
2.
J Chromatogr A ; 1626: 461356, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797836

RESUMO

The presence of organophosphate esters (OPEs) in everyday commodities such as furniture, household appliances and baby toys have rendered these contaminants ubiquitous in environmental fates such as air, water, soils and biota. Their presence in food-related species suggests that an additional route of exposure to these esters for the general population is fish intake through diet. Their incipient toxicity and carcinogenetic behaviour make it essential to develop methods for determining OPEs in fish samples. In this paper we have developed a new method for determining 9 OPEs based on the QuEChERS extraction method followed by a simple clean-up using a novel device for selective lipid removal (LipiFiltr) and GC-MS/MS to extract these compounds from fish samples regardless of lipid content. QuEChERS salt packet optimisation and clean-up strategies such as liquid-liquid extraction, dispersive-solid phase extraction and LipiFiltr were tested. Our results showed that EN 15662 method salts and Lipifiltr were the best combination to produce efficient analyte apparent recovery (67-116%) and negligible matrix effects (<10%). Limits of detection ranged from 0.05 ng g-1 (dry weight) for TiBP and TBP to 2.00 ng g-1 (dry weight) for TCEP. Fish samples from four fish species were determined with a median concentration of ΣOPEs 5.31 ng g-1 on a wet weight basis, with TBP, TiBP and TCPP as the main contenders. Estimates of exposure and risk associated with consuming these compounds via dietary intake showed low levels of concern for the population of Tarragona.


Assuntos
Ésteres/análise , Peixes/metabolismo , Retardadores de Chama/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Organofosfatos/análise , Plastificantes/análise , Medição de Risco , Espectrometria de Massas em Tandem , Adolescente , Adulto , Idoso , Animais , Criança , Dieta , Monitoramento Ambiental , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Espectrometria de Massas em Tandem/métodos , Adulto Jovem
3.
J Chromatogr A ; 1626: 461389, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797860

RESUMO

The reliable measurement of very volatile organic compounds (VVOC) in indoor air by use of thermal desorption gas chromatography (TD-GC) in order to include them into evaluation schemes for building products even nowadays is a great challenge. For capturing these small molecules with carbon numbers ranging from C1C6, strong adsorbents are needed. In the present study, recovery rates of nine suitable adsorbents of the groups of porous polymers, graphitised carbon blacks (GCB) and carbon molecular sieves (CMS) are tested against a complex test gas standard containing 29 VVOC. By consideration of the recovery and the relative humidity (50% RH), combinations of the GCB Carbograph 5TD, the two CMS Carboxen 1003 and Carbosieve SII as well as the porous polymer Tenax® GR were identified to be potentially suitable for sampling the majority of the VVOC out of the gas mix. The results reveal a better performance of the adsorbents in combination than being used alone, particularly under humid sampling conditions. The recovery rates of the chosen compounds on each adsorbent should be in the range of 80-120%.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos Voláteis/análise , Adsorção , Carbono/química , Gases/química , Umidade , Polímeros/química , Temperatura
4.
J Chromatogr A ; 1627: 461397, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823102

RESUMO

A new and sensitive analytical method for the simultaneous determination of secondary lipid peroxidation aldehydes has been successfully developed and validated. Malondialdehyde, acrolein, formaldehyde, acetaldehyde, propanal, and pentanal were extracted and derivatized using 2,4-dinitrophenylhydrazine (DNPH) by gas-diffusion microextraction (GDME) combined with dispersive liquid-liquid microextraction (DLLME) for gas chromatography-mass spectrometry (GC-MS) analysis. The experimental conditions have been optimized by experimental designs. The analytical method validation, in accordance to the Food and Drug Administration (FDA) guidance, provided good results in terms of linearity with r2≥0.9974, in the range from 0.15 or 0.3 µg·g-1 to 3 µg·g-1. Limits of detection and limits of quantification were 0.05 or 0.10 and 0.15 or 0.3 µg·g-1, respectively. Precision was tested as a relative standard deviation (RSD≤ 9.5%) and recoveries were between 95% and 110%. The method was applied in the characterization of aldehydes in forty-eight edible oil samples; with the highest concentration found in pomace olive oil for malondialdehyde at 6.64 µg·g-1.


Assuntos
Acetaldeído/análise , Acroleína/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Líquida/métodos , Malondialdeído/análise , Óleos Vegetais/análise , Acetaldeído/isolamento & purificação , Acroleína/isolamento & purificação , Aldeídos/análise , Aldeídos/isolamento & purificação , Limite de Detecção , Peroxidação de Lipídeos , Malondialdeído/isolamento & purificação , Azeite de Oliva/análise , Reprodutibilidade dos Testes
5.
J Chromatogr A ; 1627: 461398, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823103

RESUMO

A new mode of dispersive solid phase extraction based on in situ formation of adsorbent in aqueous phase has been introduced as an efficient method for the extraction of some pesticide residues in fruit juice samples. In this method, polycarbonate which is an inexpensive polymer is used as an adsorbent for the first time. The method is followed by dispersive liquid-liquid microextraction for more enrichment of the analytes. In the present study, a proper amount of the polymer is dissolved in N,N-dimethyl formamide and the obtained solution is injected into an aqueous phase containing the analytes. After injection, polycarbonate particles are formed and adsorbed the analytes. Then, the adsorbent is separated from the aqueous solution and eluted by acetone. The obtained acetone phase is mixed with 1,1,1-trichloroethane and the mixture is dispersed into deionized water and a cloudy solution is formed. Ultimately, after centrifugation, the obtained sedimented phase containing the extracted analytes is injected into gas chromatography-flame ionization detection. In the proposed method, the adsorbent synthesis step, which often is a time-consuming, expensive, and laborious step in most adsorbent-based sample preparation methods, has been removed. Moreover, there is no need for sonication or vortex agitation. Under the optimized experimental conditions, the relative standard deviation was equal or less than 7% for intra- (n = 6) and inter-day (n = 5) precisions at a concentration of 50 µg L-1 of each pesticide. The limits of detection and quantification were in the ranges of 0.34-1.2 and 1.1-4.0 µg L-1, respectively. In addition, extraction recoveries and enrichment factors varied in the ranges of 44-89% and 220-443, respectively.


Assuntos
Sucos de Frutas e Vegetais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Centrifugação , Limite de Detecção , Microextração em Fase Líquida/métodos , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida , Solventes/química , Triazinas/análise , Triazinas/isolamento & purificação , Água/química
6.
J Chromatogr A ; 1627: 461401, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823106

RESUMO

Tile-based Fisher ratio (F-ratio) analysis has recently been developed and validated for discovery-based studies of highly complex data collected using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). In previous studies, interpretation and utilization of F-ratio hit lists has relied upon manual decomposition and quantification performed by chemometric methods such as parallel factor analysis (PARAFAC), or via manual translation of the F-ratio hit list information to peak table quantitative information provided by the instrument software (ChromaTOF). Both of these quantification approaches are bottlenecks in the overall workflow. In order to address this issue, a more automatable approach to provide accurate relative quantification for F-ratio analyses was investigated, based upon the mass spectral selectivity provided via the F-ratio spectral output. Diesel fuel spiked with 15 analytes at four concentration levels (80, 40, 20, and 10 ppm) produced three sets of two class comparisons that were submitted to tile-based F-ratio analysis to obtain three hit lists, with an F-ratio spectrum for each hit. A novel algorithm which calculates the signal ratio (S-ratio) between two classes (eg., 80 ppm versus 40 ppm) was applied to all mass channels (m/z) in the F-ratio spectrum for each hit. A lack of fit (LOF) metric was utilized as a measure of peak purity and combined with F-ratio and p-values to study the relationship of each of these metrics with m/z purity. Application of a LOF threshold coupled with a p-value threshold yielded a subset of the most pure m/z for each of the 15 spiked analytes, evident by the low deviations (< 5%) in S-ratio relative to the true concentration ratio. A key outcome of this study was to demonstrate the isolation of pure m/z without the need for higher level signal decomposition algorithms.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Algoritmos , Compostos de Anilina/química , Bromobenzenos/química , Álcoois Graxos/química , Gasolina/análise , Espectrometria de Massas
7.
PLoS One ; 15(8): e0237881, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817641

RESUMO

At present, the identification of honeysuckle aroma depends on experienced tasters, which results in inconsistencies due to human error. The key odorants have the potential to distinguish the different species and evaluate the quality of honeysuckle. Hence, in this study, a more scientific approach was applied to distinguish various honeysuckles. The volatile compounds of different species and parts of honeysuckle were separately extracted by headspace-solid phase microextraction (HS-SPME) and solvent assisted flavor evaporation (SAFE). Compounds with greater volatility such as aldehydes, limonene, γ-terpinene, and terpinolene were preferentially extracted by HS-SPME. As a complementary extraction method to HS-SPME, SAFE was found to recover comparatively more polar compounds such as eugenol, decanoic acid, and vanillin. Subsequently, key odorants with the highest flavour dilution (FD) factors were detected by aroma extract dilution analysis (AEDA). These were benzaldehyde, 4-ethylphenol, decanoic acid, vanillin, 3-methyl-2-butenal, and ß-ionone in honeysuckle flowers and γ-octalactone, 4-ethyl phenol, and vanillin in honeysuckle stem. Finally, principal component analysis (PCA) was conducted to analyze not only the key odorants of species and parts of honeysuckle but also their different origins. The results of PCA suggested that the species of honeysuckle contributed much more to variations in aroma rather than their origins. In conclusion, the application of the key odorants combined with PCA was demonstrated as a valid approach to differentiate species, origins, and parts of honeysuckle.


Assuntos
Lonicera/química , Odorantes/análise , Olfatometria/métodos , Microextração em Fase Sólida/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Lonicera/classificação , Lonicera/metabolismo , Solventes/química
8.
Bull Environ Contam Toxicol ; 105(3): 460-467, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32839840

RESUMO

A green, sensitive and accurate dispersive liquid-liquid microextraction (DLLME) method was used to preconcentrate four selected pesticides in dam lake water samples for determination by gas chromatography-mass spectrometry (GC-MS). Conditions of the DLLME method were comprehensively investigated and optimized according to type/volume of extraction solvent, type/volume of dispersive solvent, and type/period of mixing. The developed method was validated according to the limits of detection and quantitation, accuracy, precision and linearity. Under the optimum conditions, limit of detection values calculated for alachlor, acetochlor, metolachlor and fenthion were 1.7, 1.7, 0.2 and 7.8 µg/kg (mass based), respectively. The method recorded 202, 104, 275 and 165 folds improvement in detection power values for acetochlor, alachlor, metolachlor and fenthion, respectively, when compared with direct GC-MS measurements. In order to evaluate the accuracy of the developed method, real sample application with spiking experiments was performed on dam lake water samples, and satisfactory percent recovery results in the range of 81%-120% were obtained.


Assuntos
Microextração em Fase Líquida/métodos , Praguicidas/análise , Poluentes Químicos da Água/análise , Acetamidas/análise , Fention/análise , Água Doce/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limite de Detecção , Solventes/análise , Toluidinas/análise
9.
J Chromatogr A ; 1625: 461336, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709360

RESUMO

Thermal desorption aerosol gas chromatography mass spectrometry is capable of online measuring speciated organics in atmospheric aerosols. Compared to the one-dimensional gas chromatography, comprehensive two-dimensional gas chromatography increases the resolution and the sensitivity, mitigates the unresolved complex mixture and co-elution occurred in one-dimensional gas chromatography. In this study, we report a quartz filter-based thermal desorption aerosol comprehensive two-dimensional gas chromatography mass spectrometry (2D-Q-TAG). It combines a solid-state thermal modulator with a quartz filter-based thermal desorption aerosol gas chromatography mass spectrometry. The solid-state thermal modulator conducts modulation independently from the chromatographic oven without using cryogens or compressed air, which makes the system readily adaptive for field measurement. The 2D-Q-TAG was evaluated using C7-C40 n-alkanes and 16 polycyclic aromatic hydrocarbons (PAHs). It has low limits of detection from 0.001 to 0.104 ng. The instrument was then deployed to measure atmospheric PM2.5 (particulate matter with an equivalent aerodynamic diameter  ≤  2.5 µm) in urban Beijing. It allows in-situ detection of speciated organics in atmospheric aerosols with hourly time resolution. Organic classes including alkanes, furanones, alcohols, aldehydes, ketones, acids, PAHs, oxy-PAHs, and alkyl-naphthalenes were well separated and detected. The total mass concentration of n-alkanes ranged from 122.1 to 629.9 ng/m3. Diurnal variation of n-alkanes was captured due to the high time resolution of the instrument.


Assuntos
Aerossóis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos/análise , Temperatura , Aerossóis/química , Alcanos/análise , Atmosfera/química , Limite de Detecção , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Padrões de Referência , Fatores de Tempo
10.
J Chromatogr A ; 1623: 461210, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505294

RESUMO

Illegal dietary supplements adulterated with phosphodiesterase type 5 inhibitors (PDE-5i) are increasingly widely distributed through internet markets and underground routes. For this reason, it demands development of reliable screening methods to determine a wide range of PDE-5i drugs in various types of dietary supplements. Herein, we developed a screening method using gas chromatography-mass spectrometry (GC-MS) for simultaneous detection of 53 PDE-5i drugs in supplements. Common formulations (such as capsule, powder, pill, and tablet) of supplements with complicated matrices were treated by simple liquid-liquid extraction and trimethylsilyl (TMS) derivatization. With the aid of TMS derivatization, 53 PDE-5i drugs could be successfully separated and detected within 15 min, using a short microbore GC column (15 m). Moreover, owing to enhanced detection sensitivity and selectivity of PDE-5i TMS derivatives, 0.5 mg of sample was sufficient to screen and confirm targeted PDE-5i drugs. In this study, specific common ions according to structural characteristics of PDE-5i drugs were found under the electron ionization (EI) of their TMS derivatives. These specific common fragments could reflect the common pharmacophores for 4 classes of PDE-5i drugs (sildenafil, other sildenafil, vardenafil, and tadalafil analogues). Based on characteristic EI fragment ions, extracted common ion chromatograms (ECICs) and discriminant analysis (DA) were effectively used for reliable screening and classification of various types of PDE-5i drugs. Specific ECICs and DA using characteristic EI fragments here will aid in identification of newly emerging PDE-5i counterfeits in supplements. This study will be helpful to supervise illegal adulteration of PDE-5i drugs in dietary supplements to protect public health and consumer safety.


Assuntos
Suplementos Nutricionais/análise , Avaliação Pré-Clínica de Medicamentos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Inibidores da Fosfodiesterase 5/análise , Análise Discriminante , Íons , Citrato de Sildenafila/análise , Tadalafila/análise , Fatores de Tempo , Dicloridrato de Vardenafila/análise
11.
J Chromatogr A ; 1624: 461259, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540084

RESUMO

An analytical procedure for the rapid and selective derivatization of free fatty acids into methyl esters directly in plasma without transmethylation of lipid-bound fatty acids was developed for their analysis by gas chromatography-mass spectrometry. The methyl esters of free fatty acids were obtained by reaction with methyl iodide in the solution of dipolar aprotic solvents and in the presence of solid bases. The mechanism of the methylation reaction with these reagents was investigated. Optimal conditions for the selective methylation of free fatty acids were established using different dipolar aprotic solvents and different solid bases. The possible transmethylation of covalently bonded fatty acids from plasma lipids has been investigated under different experimental conditions in order to be avoided. Total methylation of free fatty acids was achieved in 1 min at room temperature using methyl iodide and anhydrous potassium carbonate or sodium carbonate in dimethyl sulfoxide. Under these conditions, transmethylation of lipid-bound fatty acids was avoided. The methyl esters can be injected directly from the reaction solvents. A plasma volume of 50 µL was used without special purification. The detection limits were around 0.1 ng/µL. The proposed method avoids the drawbacks of the previous methods used for the one-step analysis of individual free fatty acids in human plasma.


Assuntos
Ácidos Graxos não Esterificados/sangue , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Limite de Detecção , Metilação , Reprodutibilidade dos Testes , Solventes/química , Ácidos Esteáricos/química
12.
Chemosphere ; 257: 127174, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32497839

RESUMO

Off-flavor events in tap water have been reported from various regions of Japan. Fishy smell is the second most common off-flavor in Japan and Uroglena americana (U. americana) is known to be a major contributor to the smell. However, the causative compound of the smell it produces still remains unrevealed to the best of our knowledge. In this study, an exploration of odorous aldehydes and ketones originating from U. americana was performed with a view to discovering a possible candidate substance of causative compounds. Environmental samples containing U. americana colony and cultured media with U. americana were analyzed with two high resolution mass spectrometers, one of them is coupled with liquid chromatography (LC-HRMS), and the other is with gas chromatography and a sniffing port (GC-O-HRMS). Multivariate analyses (MVA) were utilized to explore a compound that is likely to be odorous aldehydes or ketones with a reduced time of exploration. A combination of LC-HRMS and MVA resulted in the selection of one candidate substance and its formula was determined to be C13H20O3 on the basis of its accurate mass and natural isotopic pattern. The candidate substance underwent GC-O-HRMS analyses and milk-like smell was detected at around its retention time. Although the detected smell was different from fishy smell, it is expected that the fishy smell is caused by multiple compounds to which the candidate substance belongs. First generation product ion spectra of the candidate substance suggested that it contains a hydroxyl group, a cyclohexene ring, and a ketone moiety.


Assuntos
Aldeídos/análise , Chrysophyta/fisiologia , Cetonas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Japão , Espectrometria de Massas , Análise Multivariada , Odorantes/análise , Olfatometria/métodos , Olfato , Paladar
13.
PLoS One ; 15(6): e0233516, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32479498

RESUMO

The Balkans endemic species Alkanna primuliflora Griseb., A. stribrnyi Velen., and A. graeca Boiss. & Spruner have limited distribution in the Balkan Peninsula and a large variation in the morphological characteristics. The populations of the three Alkanna species in the Bulgarian flora are small and fragmented. There are no previous reports on the chemical profile or on the embryology of these species. The hypothesis was that the limited distribution of A. primuliflora, A. stribrnyi, and A. graeca was due to their reproductive capacity and genetic diversity. Furthermore, we hypothesized that the three species will contain pyrrolizidine alkaloids (PAs), as other species of the genus Alkanna (Boraginaceae), but they would have differential alkaloids composition. The population genetic structure and differentiation showed a clear distinction between species and revealed average levels of genetic diversity among the natural populations of the three Alkanna species. The embryological investigation observed stability of the processes in the male and female generative spheres and high viability of mature pollen and embryo of the three species. The normal formation of male and female gametophytes without deviations or degenerative processes, and observed levels of genetic diversity between Alkanna individuals are important in maintaining the size and resilience of the Alkanna populations. Eight alkaloids were identified by GC-MS in A. primuliflora and A. graeca and six alkaloids in A. stribrnyi. The main pyrrolizidine alkaloids (PAs) in all investigated species was triangularine. A. primuliflora and A. graeca showed similar chemical composition that comprised 9-angeloylretronecine, 7-tigloylretronecine, 9-tigloylretronecine, triangularicine, dihydroxytriangularine, dihydroxytriangularicine, whereas, in A. stribrnyi 9-tigloylretronecine, triangularicine and dihydroxytriangularicine were not found. This is the first report on the presence of PAs in A. primuliflora, A. stribrnyi and A. graeca. Besides, this is the first report on the embryology of these endemic species. The results contribute to the knowledge of the three endemic Alkanna species and will facilitate policy-making and defining new strategies for their conservation.


Assuntos
Boraginaceae/química , Boraginaceae/genética , Alcaloides/análise , Península Balcânica , Boraginaceae/metabolismo , Bulgária , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Variação Genética/genética , Extratos Vegetais/química , Alcaloides de Pirrolizidina/química , Reprodução/fisiologia , Especificidade da Espécie
14.
J Chromatogr A ; 1623: 461170, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505276

RESUMO

In this study, a multiresidue analytical method was developed, validated, and applied for quantifying 85 persistent organic pollutants (POPs), including 38 polychlorinated biphenyls (PCBs), 23 polybrominated diphenyl ethers (PBDEs), and 24 organochlorine pesticides (OCPs) from 200 µL of human serum. A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was applied to minimize the required sample amount and optimize various conditions including the extraction solvent and the number of extractions. The extraction efficiency was optimized using double extraction with an ethyl acetate/hexane/acetone mixture. Gas chromatography coupled with triple-quadrupole mass spectrometry was used for analysis, and two different ionization sources, electron impact ionization (EI) and atmospheric pressure chemical ionization (APCI), were used to compare their sensitivity. The APCI source employed soft ionization at atmospheric pressure, producing abundant molecular ion formation with minimal fragmentation, in contrast to extensive fragmentation caused by EI. Of the 85 POPs analyzed, 59 target compounds (69.4%) showed lower limits of detection that were two- to fifty-fold lower in APCI than those determined using EI. The developed method was validated for its detection limit (0.5-10 pg/mL for PCBs, 2-20 pg/mL for PBDEs, and 2-40 pg/mL for OCPs), precision (0.8%-34.3% of coefficient of variation), recovery (49.6%-77.1%), matrix effect (46.7%-156.9%), and accuracy (81.2%-113.1% for PCBs, 85.8%-112.2% for PBDEs, and 55.2%-113.9% for OCPs). Its linearity was R2 > 0.99 for 84 compounds, and 96% average accuracy (for APCI) was obtained using the National Institute of Standards and Technology (NIST) standard reference materials (NIST 1957 and 1958). These ionization methods were compared by analyzing 25 real human serum samples. The observed species were 1.1-24.6 pg/mL of 28 PCBs, 2.5 pg/mL of BDE-47, and 6.5-195.1 pg/mL of 6 organochlorine pesticides (median concentration for each species), and only 11 compounds were detected with APCI owing to its enhanced sensitivity.


Assuntos
Poluentes Ambientais/sangue , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Acetatos/química , Acetona/química , Pressão Atmosférica , Poluentes Ambientais/isolamento & purificação , Feminino , Éteres Difenil Halogenados/sangue , Hexanos/química , Humanos , Hidrocarbonetos Clorados/sangue , Limite de Detecção , Praguicidas/sangue , Bifenilos Policlorados/sangue
15.
Yakugaku Zasshi ; 140(6): 809-818, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32475931

RESUMO

Standard analytical methods for the detection of dieldrin and 4,6-dichloro-7-(2,4,5-trichlorophenoxy)-2-trifluoromethylbenzimidazole (DTTB) in textiles, which are regulated by Japanese law ("Act on the Control of Household Products Containing Harmful Substances"), have been in place for more than 30 years. In this study, we developed an improved analytical method, based on GC-MS, that uses safe reagents and can simultaneously detect dieldrin and DTTB analytes. In the standard (existing) analytical method, dimethyl sulfate, which is a potential carcinogen, is used to derivatize DTTB. In the developed method, phenyltrimethylammonium hydroxide, as an alternative reagent, was used to derivatize DTTB in good results. Dieldrin and the derivatized DTTBs gave highly linear calibration curves when analyzed by GC-MS. Moreover, we found that both analytes are adequately extracted from textiles by refluxing in hydrochloric acid and methanol. Furthermore, we established a purification method using the Bond Elut PRS column that effectively removed interfering substances in woolen products. Finally, we developed an improved analysis method by combining the above-mentioned techniques; the developed method exhibited a recovery rate of 94-104% and a relative standard deviation of less than 7% for both analytes. In addition, the limits of quantitation (dieldrin: 1.3 µg/g, DTTB: 0.72 µg/g) were sufficiently lower than the Japanese regulatory value of 30 µg/g.


Assuntos
Benzimidazóis/análise , Dieldrin/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Têxteis/análise , Indicadores e Reagentes , Compostos de Amônio Quaternário
16.
Food Chem ; 331: 127335, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32574944

RESUMO

Comprehensive 2D gas chromatography-time-of-flight mass spectrometry was combined with descriptive sensory analysis to elucidate the specificity of strong-aroma type Baijiu (Chinese liquor) from different regions, based on regionally distinct flavor characterized by chemical and sensory profiles. Numerous potential aroma compounds (262) were identified, among which 58 aroma compounds were significantly different between the samples from Sichuan and Jianghuai regions. Relationships between these potential aroma compounds and sensory attributes were investigated by partial least squares regression and network analysis. The compounds that dominantly contributed to the important sensory attributes were identified. The high pyrazines, furanoids, and carbonyls amounts contributed to the high intensities of the cellar, toasted, and grain aroma profiles of the Sichuan region samples, while the high ester and alcohol levels contributed to the fruity and floral aroma profiles of the Jianghuai region samples. This approach may have practical application in flavor characterization of other alcoholic beverages.


Assuntos
Bebidas Alcoólicas/análise , Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Odorantes/análise , Compostos Orgânicos Voláteis/análise , China , Ésteres/análise , Análise de Alimentos/estatística & dados numéricos , Cromatografia Gasosa-Espectrometria de Massas/estatística & dados numéricos , Humanos , Análise dos Mínimos Quadrados , Análise Multivariada , Pirazinas/análise , Paladar
17.
Food Chem ; 331: 127358, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32593795

RESUMO

Saffron, stigmas of Crocus sativus, is one of the most precious spices used as food colorant and flavoring agent. Due to its scarce source and high cost, it is liable to fraudulent admixture with allied plants "safflower and calendula". In this study, gas chromatography-mass spectrometry (GC-MS) was employed to determine authenticity, adulterants detection, and to assess the roasting impact on its aroma. A total of 93 volatiles were identified belonging to different classes viz. aldehydes, alcohols, ketones, aliphatic hydrocarbons, aromatics, mono-and sesquiterpenes, oxides/ethers and pyrans/furans. Principle component analysis (PCA) identified safranal and 2-caren-10-al as discriminatory volatile markers of saffron from its allied flowers, later found enriched in estragole, ß-caryophyllene and eugenol. PCA model also revealed markers for freshly dried versus long-stored saffron, with ketoisophorone as freshness marker versus safranal as an ageing indicator. Safranal was further identified as a marker to distinguish saffron from safflower, whereas calendula aroma was predominated by monoterpene hydrocarbons.


Assuntos
Crocus/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Especiarias/análise , Compostos Orgânicos Voláteis/análise , Biomarcadores/análise , Calendula/química , Carthamus tinctorius/química , Cicloexanonas/análise , Cicloexenos , Flores/química , Análise de Alimentos/métodos , Armazenamento de Alimentos , Indústria de Processamento de Alimentos , Irã (Geográfico) , Odorantes/análise , Espanha , Terpenos
18.
Food Chem ; 330: 127330, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32569941

RESUMO

Conventional analysis, electronic senses and HS-SPME-GC-MS were applied to evaluate the effects of pretreatment methods and leaching methods on jujube wine quality. Significant differences (p < 0.05) in the levels of alcohol content, color, taste and aroma were observed among all the jujube wine samples, in which the pulp and pectase fermented jujube wine was the best among all. Moreover, rather than taste, aroma is the most significantly (p < 0.05) affected. In regard to aroma, a total of 182 volatile compounds were identified by HS-SPME-GC-MS. It was found that the blended-into-pulp treatment and the leached-by-pectase treatment had notable positive effects on jujube wine. The pulp and pectase fermented jujube wines exhibited the highest concentration of total volatile compounds as well as alcohols, esters, acids and aldehydes. Thus, the optimal pretreatment method and leaching method for jujube wine fermentation are blended-into-pulp and leached-by-pectase respectively.


Assuntos
Análise de Alimentos/métodos , Qualidade dos Alimentos , Vinho/análise , Ziziphus , Álcoois/análise , Aldeídos/análise , Cor , Nariz Eletrônico , Ésteres/análise , Fermentação , Análise de Alimentos/estatística & dados numéricos , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Análise Multivariada , Odorantes/análise , Microextração em Fase Sólida/métodos , Paladar , Compostos Orgânicos Voláteis/análise , Ziziphus/química
19.
Food Chem ; 331: 127207, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569964

RESUMO

Reconstituted polyphenolic and aromatic fractions (PAFs) from 33 different Garnacha and Tempranillo grapes were incubated in strict anoxia (75 °C × 24 h). Obtained hydrolyzates were characterized by sensory analysis, gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Five different aroma categories emerged. Garnacha may develop specific tropical/citrus fruit, kerosene and floral and Tempranillo toasty-woody and red-fruit characteristics. Those notes seem to mask alcoholic and fruit-in-syrup descriptors and the common vegetal background. Twenty-seven odorants were detected by GC-O. GC-MS data showed a clustering closely matching the one found by sensory analysis, suggesting the existence of five specific metabolomic profiles behind the five specific sensory profiles. Overall results suggest that 3-mercaptohexanol is responsible for tropical/citrus fruit, TDN for kerosene, volatile phenols for woody/toasty, ß-damascenone and massoia lactone, likely with Z-1,5-octadien-3-one for fruit-in-syrup and alcoholic notes. Nine lipid-derived unsaturated aldehydes and ketones may be responsible for the vegetal background.


Assuntos
Vitis/química , Compostos Orgânicos Voláteis/análise , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hexanóis/química , Norisoprenoides/química , Odorantes/análise , Olfatometria , Análise de Componente Principal , Compostos de Sulfidrila/química
20.
Chemosphere ; 258: 127273, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554005

RESUMO

This work describes the design, optimization and validation of an analytical method for the simultaneous determination of 14 pharmaceuticals and personal care products (PPCPs) in sewage sludge. A thorough optimization of the sample pre-treatment was carried out. As a result, microwave-assisted extraction (MAE) was combined with an in-situ clean-up stage and a filtration step. A combination of MilliQ® water/MeOH 95:5 (v/v) adjusted to pH 9 turned out to be the optimal solvent mixture for extraction. The instrumental part of the method presents a significant novelty based on a fully automated sample preparation for the analysis of PPCPs. It consisted of a direct immersion solid phase microextraction followed by on-fiber derivatization, online coupled to gas chromatography - mass spectrometry (DI-SPME-On-fiber derivatization - GC-MS). An isotope dilution approach was used for quantifying, which conferred high reliability to the method. This methodology was validated for 10 compounds with good analytical performance, limit of detection below 20 ng g-1 and absolute recovery in the range of 30-70% for most of the compounds. It supposes an ecological analytical alternative for many routine analysis laboratories around the world. The developed method was applied to different real samples generated in both a pilot-scale thermal hydrolysis treatment plant and an anaerobic digester operated in mesophilic conditions. Salicylic acid and naproxen were found at concentrations above 1000 ng g-1.


Assuntos
Cosméticos/análise , Micro-Ondas , Preparações Farmacêuticas/análise , Esgotos/química , Solventes/química , Poluentes Químicos da Água/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Metanol/química , Reprodutibilidade dos Testes , Microextração em Fase Sólida/métodos , Água/química
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