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1.
Mass Spectrom Rev ; 42(5): 1808-1827, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35638257

RESUMO

Traditional Chinese medicines (TCMs) have been widely used in clinical and healthcare applications around the world. The characterization of the phytochemical components in TCMs is very important for studying the therapeutic mechanism of TCMs. In the analysis process, sample preparation and instrument analysis are key steps to improve analysis performance and accuracy. In recent years, chromatography combined with mass spectrometry (MS) has been widely used for the separation and detection of trace components in complex TCM samples. This article reviews various sample preparation techniques and chromatography-MS techniques, including the application of gas chromatography-MS and liquid chromatography-MS and other MS techniques in the characterization of phytochemicals in TCM materials and Chinese medicine products. This article also describes a new ambient ionization MS method for rapid and high-throughput analysis of TCM components.

2.
J Fluoresc ; 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38753257

RESUMO

The accurate and sensitive detection of prostate specific antigen (PSA) is vital for the early diagnosis and treatment of prostate cancer. To this end, an unlabeled fluorescent aptasensor was constructed by using a novel Compound B {1,1'-(1,4-phenylene) bis(3-ethyl-1H-imidazol-3-ium) iodide} with aggregation-induced emission (AIE) activity as a fluorescence signal and NH2-Fe3O4 particle as an adsorption platform. Compound B could combine with prostate specific antigen aptamers (PSA-Apt) to form a PSA-Apt/B complex, which further generated the AIE effect. Then, PSA was added to the PSA-Apt/B solution. PSA combined with PSA-Apt/B to form the PSA-Apt/B/PSA complex. Next, NH2-Fe3O4 magnetic particles were added to the solution. Given that PSA-Apt/B/PSA would no longer combine with NH2-Fe3O4 magnetic particles, the PSA-Apt/B/PSA complex remained in the supernate after magnet separation, and the supernate showed strong fluorescence (I). When no PSA was added to the PSA-Apt/B solution, PSA-Apt/B could combine with NH2-Fe3O4 magnetic particles and would be sucked into the bottom of the test tube by magnet, and the supernate would show weak fluorescence (I0). Result showed that the difference between the above-mentioned two fluorescence values (∆I = I - I0) had an excellent linear relationship with the PSA concentration within the concentration range of 0.01-10 ng/mL, and its limit of detection was 3 pg/mL (S/N = 3). In addition, the sensor has high accuracy and can be directly used to test PSA in actual serum samples.

3.
J Sep Sci ; 42(18): 2968-2976, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31273899

RESUMO

A high-throughput method based on ultrasonic-assisted extraction, 96-well plate thin-film microextraction was established to determinate 18 antibiotics in animal feed. In this method, the extraction was implemented by ultrasonic-assisted extraction for 30 min with disodium ethylenediaminetetraacetic acid-McIlvaine buffer (pH 5) containing 6% sodium chloride w/v, purified by thin-film microextraction and combined with 96-well plate system to improve the efficiency. Optimization of thin-film microextraction conditions was performed by methods of single factor and response surface, and finalized as: condition time: 20 min; adsorption time: 55 min; washing time: 5 s with water; desorption time: 30 min with acetonitrile/water (8:2, v/v) containing 0.1% formic acid v/v. Evaluation of different extractive phases showed that polystyrene-divinylbenzene-polyacrylonitrile was the optimum coating. The analysis was performed by ultra-high performance liquid chromatography with tandem mass spectrometry. Recovery, inter- and intraday precision, linearity, limit of detection, and quantitation were evaluated. The average recoveries of 18 antibiotics were 66.6-93.5% at three spiked levels, intraday precision was 1-8.4%, and interday precision was 3.0-16.4%. The linearity was good for r2  > 0.99. Limits of detection and quantification were found in the range of 1-14 and 4-48 µg/kg, respectively.


Assuntos
Ração Animal/análise , Antibacterianos/análise , Ensaios de Triagem em Larga Escala , Microextração em Fase Líquida , Animais , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas em Tandem
4.
Ecotoxicol Environ Saf ; 182: 109470, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31352212

RESUMO

In the past few years, polyhalogenated carbazoles (PHCZs) have been of increasing concern because their structure is similar to that of legacy POPs. In the present study, an analytical method, including intensive cleanup and fractionation procedures in combination with instrumental parameters, was developed to determine ultratrace polyhalogenated carbazoles (PHCZs) in soil and sediment. The eluting sorbents, volume and packing of the column were optimized. Our results showed that 5 g of florisil and 4 g of silica gel under 150 mL of hexane/DCM = 3:1 presented good performance in terms of recovery and repeatability. GC-HRMS, GC-MS/MS (EI-MRM) and GC-MS (EI-SIM) were applied to compare the performance of PHCZ analysis. For sensitivity, EI-MRM presents method detection limits comparable to those of GC-HRMS and much lower than those of EI-SIM. Regarding selectivity, GC-HRMS performed better than the other two techniques since GC-HRMS can reduce interference from perfluorokerosene (PFK) and DDX (DDT, DDE, and DDD) due to its high resolution. GC-HRMS was then further optimized by shortening the run time and modifying the SIM ion. The final method was successfully applied to determine PHCZs in soil and sediment, and the target compounds had almost 100% detection frequency in the samples. The ubiquitous presence of PHCZ in soil and sediment calls for a further investigation of its source, distribution and degradation in the environment.


Assuntos
Carbazóis/análise , Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Hidrocarbonetos Halogenados/análise , Poluentes do Solo/análise , Solo/química , Cromatografia Gasosa-Espectrometria de Massas , Hexanos/química , Limite de Detecção , Silicatos de Magnésio/química , Dióxido de Silício/química , Espectrometria de Massas em Tandem
5.
J Sep Sci ; 41(15): 3089-3096, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29863309

RESUMO

A syringe-dispersive solid-phase extraction method was developed for the determination of seven nitroimidazoles and nine steroids in manure-based fertilizers by ultra-high performance liquid chromatography with tandem mass spectrometry. Methanol and acetonitrile were used to extract the sample, and mixed dispersive sorbents dispersed in the syringe were used for purification. The extract was separated with an HSS-T3 column and detected in positive or negative multiple reaction monitoring mode. Under the optimal conditions, the recoveries of the 16 compounds ranged from 70.3 to 112.3% at the four spiked levels (3, 10, 20, and 50 µg/kg) and the relative standard deviations ranged from 1.0 to 12.4%. The limits of detection and quantification were 0.22-0.86 and 0.73-2.87 µg/kg, respectively. This method is simple, fast, and reliable, and can be used to simultaneously screen and determine nitroimidazoles and steroids in manure-based fertilizers.


Assuntos
Fertilizantes/análise , Nitroimidazóis/análise , Extração em Fase Sólida , Esteroides/análise , Seringas , Cromatografia Líquida de Alta Pressão
6.
J Sep Sci ; 41(24): 4498-4505, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30358087

RESUMO

A novel microwave-assisted-demulsification dispersive liquid-liquid microextraction technique was established for determination of three triazole fungicides in environmental water samples by gas chromatography with mass spectrometry. Importantly, microwave irradiation has been applied in demulsification to achieve the phase separation and enrichment of triazole fungicides in water samples successfully with low-density toluene as extractant. The experimental variables, including microwave power, microwave time, ultrasonic time, type and volume of extraction solvent, and effect of salting out were investigated. Under the optimized conditions, the method showed good linearity for myclobutanil, tebuconazole, and difenoconazole in the range of 1-100 µg/L. The limits of detection and the limits of quantification were within the range of 0.14-0.27 and 0.47-0.90 µg/L, respectively. The suitable enrichment factors for three triazole pesticides were in the range of 425-636. The recoveries were between 89.3 and 108.7%, and the relative standard deviations were from 5.4 to 8.6%. Finally, environmental water samples were used to verify the applicability of the proposed method for analysis of triazole fungicides targets. It can be concluded that the developed microwave-assisted-demulsification dispersive liquid-liquid microextraction gas chromatography with mass spectrometry method was a rapid, efficient, reliable, and environmental friendly way for analysis of triazole fungicides in water.


Assuntos
Fungicidas Industriais/análise , Microextração em Fase Líquida , Micro-Ondas , Triazóis/análise , Poluentes Químicos da Água/química , Cromatografia Gasosa-Espectrometria de Massas
7.
J Sep Sci ; 41(3): 756-764, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29125696

RESUMO

An analytical method for the simultaneous determination of 13 mycotoxins in feed by magnetic dispersive solid-phase extraction combined with ultra-high performance liquid chromatography and tandem mass spectrometry was developed. The samples were extracted with acetonitrile/water (80:20, v/v, containing 3% acetic acid), and separated by centrifugation after salting-out, and then treated with magnetic adsorbents to remove interferences. The separation of target mycotoxins was performed on an ACQUITY UPLC HSS T3 column using a mobile phase consisting of 1 mmol/L ammonium acetate with 0.1% formic acid and methanol by gradient elution. Good linearities for the 13 mycotoxins were achieved with correlation coefficients over 0.99, and the recoveries of mycotoxins were in the range of 89.3-112.6% at spiking at levels of 5, 20, and 100 µg/kg, with relative standard deviations of 0.9-10.4%. Based on the functional magnetic materials (MDN@Fe3 O4 , PSA@Fe3 O4 , ZrO2@ Fe3 O4 ) applied in dispersive solid-phase extraction, the pretreatment process is more convenient and it is beneficial to reduce the experimental cost by reusing the recycled magnetic materials. It is a simple, rapid, and environmentally friendly analytical method for the determination of mycotoxins in feed.


Assuntos
Ração Animal/análise , Cromatografia Líquida de Alta Pressão , Micotoxinas/análise , Espectrometria de Massas em Tandem , Acetatos , Acetonitrilas , Adsorção , Contaminação de Alimentos , Formiatos , Limite de Detecção , Modelos Lineares , Magnetismo , Metanol , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Extração em Fase Sólida , Difração de Raios X
8.
Bull Environ Contam Toxicol ; 100(6): 754-759, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29713751

RESUMO

Eighty ducks (Sheldrake, Anas platyrhynchos) from Zhejiang Province, China were fed capsules containing commercialized hexabromocyclododecanes (HBCDs) at low (0.8 mg/kg/day) or high (1.6 mg/kg/day) exposure level, or only maize starch for 21 days. Then the next 21 days was set as depuration period. Ducks were euthanizated at 0, 7, 14 and 21 days after last dose and ten duck tissues including skin, tongue, intestines, heart, gizzard, muscle, liver, lung, brain and blood were sampled, separately. Three HBCDs including α-HBCD, ß-HBCD and γ-HBCD in duck tissue samples were analyzed. At the end of depuration period, the total HBCDs concentration in skin was significantly higher than those in the other tissues (p < 0.05). The elimination rates of the three isomers in skin, tongue, intestines, heart, gizzard and brain were in the order ß- > γ- > α-HBCD. The enantioselectivity of three HBCDs enantiomers was also studied in ten duck tissues. It was shown that the EF (enrichment factor) for two γ-HBCD enantiomers was significant lower than 0.5 (p < 0.05) in gizzard, heart, muscle, tongue, intestinal and liver at the end of depuration day, showing a selective accumulation of (+)-γ-HBCD in these tissues. This study provided a reference for evaluation on the accumulation of the persistent contamination of HBCDs in edible poultry.


Assuntos
Patos/metabolismo , Retardadores de Chama/metabolismo , Hidrocarbonetos Bromados/metabolismo , Animais , China , Hidrocarbonetos Bromados/química , Estereoisomerismo
9.
Rapid Commun Mass Spectrom ; 30 Suppl 1: 20-3, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27539409

RESUMO

RATIONALE: Ion-neutral complexes (INCs) are intermediates extensively existing in gas-phase ionic reactions. METHODS: Tandem mass spectrometry (MS(n) ) analysis of indolyl benzo[b]carbazoles was performed on an electrospray ionization quadrupole time-of-flight (ESI-Q-TOF) mass spectrometer in positive ion mode. RESULTS: Two competing INC-mediated reactions were obtained in the fragmentation of protonated indolyl benzo[b]-carbazoles. CONCLUSIONS: This study enriches our knowledge of the important roles of INCs in the dissociation of indole compounds in the gas phase. Copyright © 2016 John Wiley & Sons, Ltd.

10.
Environ Sci Technol ; 50(17): 9682-8, 2016 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-27479246

RESUMO

Acaricide etoxazole belongs to the ovicides/miticides diphenyloxazole class, affecting adults to lay sterile eggs by inhibiting chitin biosynthesis possibly. The reverse-phase HPLC-MS/MS method was used to determine the etoxazole enantiomers. The enantioselective degradation behavior of rac-etoxazole in liver microsomes of rat and human in vitro with NADPH was dramatically different. The t1/2 of (R)-etoxazole was 15.23 min in rat liver microsomes and 30.54 min in human liver microsomes, while 21.73 and 23.50 min were obtained for (S)-etoxazole, respectively. The Vmax of (R)-etoxazole was almost 5-fold of (S)-etoxazole in liver microsomes of rat in vitro. However, the Vmax of (S)-etoxazole was almost 2-fold of (R)-etoxazole in liver microsomes of human in vitro. The CLint of etoxazole was also shown the enantioselectivity on the contrary in liver microsomes of rat and human. These results indicated that the metabolism of two etoxazole enantiomers was selective in liver microsomes of rat and human in vitro, and enantioselectivity in the two kinds of liver microsomes was in the difference in degradation performance. The reason might be related to the composition and content involved in the enzyme system.


Assuntos
Inseticidas/metabolismo , Microssomos Hepáticos/metabolismo , Oxazóis/metabolismo , Espectrometria de Massas em Tandem , Animais , Humanos , NADP/metabolismo , Ratos , Estereoisomerismo
11.
Anal Bioanal Chem ; 408(26): 7461-71, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27580608

RESUMO

A novel method of large volume of water samples directly introduced in dispersive liquid-liquid microextraction was developed, which is based on ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas (CO2) breaking down the emulsion for the determination of 15 triazole fungicides by gas chromatography-tandem mass spectrometry. This technique makes low-density extraction solvent toluene (180 µL) dissolve in 200 mL of samples containing 0.05 mol L(-1) of HCl and 5 % of NaCl (w/v) to form a well emulsion by synergy of ultrasound and manual shaking, and injects NaHCO3 solution (1.0 mol L(-1)) to generate CO2 achieving phase separation with the assistance of ultrasound. The entire process is accomplished within 8 min. The injection of NaHCO3 to generate CO2 achieves phase separation that breaks through the centrifugation limited large volume aqueous samples. In addition, the device could be easily cleaned, and this kind of vessel could be reconfigured for any volume of samples. Under optimal conditions, the low limits of detection ranging from 0.7 to 51.7 ng L(-1), wide linearity, and enrichment factors obtained were in the range 924-3669 for different triazole fungicides. Southern end of the Beijing-Hangzhou Grand Canal water (Hangzhou, China) was used to verify the applicability of the developed method. Graphical Abstract Flow chart of ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas breaking down the emulsion.

12.
J Sep Sci ; 39(23): 4603-4609, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27734583

RESUMO

A pretreatment method named tablet-effervescence-assisted dissolved carbon flotation was introduced for the determination of four triazole fungicides in environmental water. In this method, the use of effervescent tablet composed of nontoxic sodium carbonate and sodium dihydrogen phosphate could generate CO2 in situ to assist the dispersion of extraction solvent and to accelerate mass transfer of target analytes. In addition, the simple phase separation simply based on the rising of low-density organic solvent from the aqueous phase was applied rather than the application of apparatus, which demonstrated the potential for on-site extraction in the field. The experimental variables, including the composition of effervescent tablets, amount of effervescent tablets, types and volume of extraction solvent, were investigated. Under the optimized conditions, the method showed good linearity for myclobutanil, tebuconazole, epoxiconazole, and difenoconazole in the range of 1-100 µg/L. The limits of detection and the limits of quantification were within the range of 0.15-0.26 and 0.49-0.86 µg/L, respectively. The obtained correlation coefficients varied from 0.997 to 0.999, and suitable enrichment factors were 422-589. The recoveries were 82.5-112.9% with relative standard deviations of 4.7-13.5%.


Assuntos
Fungicidas Industriais/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Triazóis/isolamento & purificação , Carbono , Cromatografia Líquida de Alta Pressão , Comprimidos , Água
13.
J Sep Sci ; 39(6): 1173-81, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26833965

RESUMO

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco.

14.
Rapid Commun Mass Spectrom ; 29(3): 263-8, 2015 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-26411624

RESUMO

RATIONALE: Ionization in electrospray ionization mass spectrometry (ESI-MS) mainly occurs as a result of acid-base reactions or coordination with metal cations. Formation of the radical cation M(+•) in the ESI process has attracted our interest to perform further investigation. METHODS: A series of indolyl benzo[b]carbazoles were investigated using a quadrupole ion trap mass spectrometer equipped with an ESI source or an atmospheric pressure chemical ionization (APCI) source in the positive-ion mode. Theoretical calculations were performed using the density functional theory (DFT) method at the B3LYP/6-31G(d) level. RESULTS: Both the radical ion M(+•) and the protonated molecule [M + H](+) were obtained by ESI-MS analysis of indolyl benzo[b]carbazoles, while only [M + H](+) was observed in the APCI-MS analysis. The relative intensities of M(+•) and [M + H](+) were significantly affected by several ESI operating parameters and the nature of the substituents. CONCLUSIONS: Formation of M(+•) and [M + H](+) was rationalized as two competing ionization processes in the ESI-MS analysis of indolyl benzo[b]carbazoles.


Assuntos
Carbazóis/química , Cátions/química , Modelos Moleculares , Prótons , Espectrometria de Massas por Ionização por Electrospray/métodos
15.
Anal Bioanal Chem ; 407(13): 3545-54, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25732092

RESUMO

An in-line matrix cleanup method was used for the simultaneous extraction of 15 sulfonamides and two metabolites from manure samples. The ultrasound/microwave-assisted extraction (UMAE) combined with solid-liquid-solid dispersive extraction (SLSDE) procedure provides a simple sample preparation approach for the processing of manure samples, in which the extraction and cleanup are integrated into one step. Ultrasonic irradiation power, extraction temperature, extraction time, and extraction solvent, which could influence the UMAE efficiency, were investigated. C18 was used as the adsorbent to reduce the effects of interfering components during the extraction procedure. The extracts were concentrated, and the analytes were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) without any further cleanup. The isotopically labeled compounds sulfamethoxazole-d 4, sulfamethazine-d 4, sulfamonomethoxine-d 4, and sulfadimethoxine-d 6 were selected as internal standards to minimize the matrix effect in this method. The recoveries of the antibiotics tested ranged from 71 to 118 % at the three spiking levels examined (20, 200, and 500 µg · kg(-1)). The limits of detections were 1.2-3.6 µg · kg(-1) and the limits of quantification were 4.0-12.3 µg · kg(-1) for the sulfonamides and their metabolites. The applicability of the method was demonstrated by analyzing 30 commercial manure samples. The results indicated that UMAE-SLSDE combined with LC-MS/MS is a simple, rapid, and environmentally friendly method for the analysis of sulfonamides and their metabolites in manure, and it could provide the basis for a risk assessment of the antibiotics in agricultural environments.


Assuntos
Fracionamento Químico/métodos , Cromatografia Líquida/métodos , Esterco/análise , Espectrometria de Massas/métodos , Sonicação/métodos , Sulfonamidas/análise , Extração Líquido-Líquido/métodos , Micro-Ondas , Doses de Radiação , Extração em Fase Sólida/métodos , Sulfonamidas/química , Sulfonamidas/efeitos da radiação , Ondas Ultrassônicas
16.
J Sep Sci ; 38(1): 121-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25348589

RESUMO

A one-step ultrasound/microwave-assisted solid-liquid-solid dispersive extraction procedure was used for the simultaneous determination of eight neonicotinoids (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid, imidaclothiz) in dried Dendrobium officinale by liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry in multiple reaction monitoring mode. The samples were quickly extracted by acetonitrile and cleaned up by the mixed dispersing sorbents including primary secondary amine, C18 , and carbon-GCB. Parameters that could influence the ultrasound/microwave-assisted extraction efficiency such as microwave irradiation power, ultrasound irradiation power, temperature, and solvent were investigated. Recovery studies were performing well (70.4-113.7%) at three examined spiking levels (10, 50, and 100 µg/kg). Meanwhile, the limits of quantification for the neonicotinoids ranged from 0.87 to 1.92 µg/kg. The method showed good linearity in the concentration range of 1-100 µg/L with correlation coefficients >0.99. This quick and useful analytical method could provide a basis for monitoring neonicotinoid insecticide residues in herbs.


Assuntos
Fracionamento Químico/métodos , Dendrobium/química , Inseticidas/química , Inseticidas/isolamento & purificação , Nitrocompostos/química , Nitrocompostos/isolamento & purificação , Extração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão/métodos , Micro-Ondas , Espectrometria de Massas em Tandem/métodos
17.
J Sep Sci ; 38(4): 599-604, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25581871

RESUMO

An efficient enantioselective method for the determination of etoxazole in orange pulp, peel, and whole orange was developed using liquid chromatography with tandem mass spectrometry. The enantioseparation was performed on a Chiralpak AD-3R column at 30ºC using acetonitrile with 0.1% formic acid solution (80:20, v/v) as the mobile phase in less than 5 min. Quantification was achieved using matrix-matched standard calibration curves. The overall mean recoveries for two enantiomers from orange pulp and whole orange were 91.0-99.6% and the orange peel was 92.6-103.1%, with relative standard deviations of 0.8-5.4% intraday and 2.0-4.8% interday at 1, 10, and 100 µg/kg levels, and 1.3-5.2% intraday and 3.5-4.3% interday at 5, 50, and 500 µg/kg levels, respectively. The limits of quantification for all enantiomers in three matrices did not exceed 5 µg/kg. Moreover, the absolute configuration of etoxazole enantiomers had been determined by the combination of experimental and predicted electronic circular dichroism spectra, and the first eluted enantiomer was confirmed as (S)-etoxazole on a Chiralpak AD-3R column while (R)-etoxazole was first on three cellulose chiral columns. The application of the proposed method to real sample analysis suggests its potential use in enantioselective determination of etoxazole enantiomers in citrus.

18.
Artigo em Inglês | MEDLINE | ID: mdl-25906035

RESUMO

Electrospray ionization mass spectrometry (ESI-MS) analyses of 2-(1,2,4-triazole-1-yl)-6-methyl-3- quinolinecarboxaldehyde were carried out by using an ion trap mass spectrometer in a positive-ion mode. Interestingly, several unusual [M + 15](+), [M + 33](+), and [M + 47](+) ions were observed with a high abundance in the ESI-MS spectrum when methanol was used as the ESI solvent. However, only the protonated molecule was obtained with acetonitrile as the ESI solvent. These unusual ions have been proposed as the intermediates of an aldolization reaction occurring in the ESI source, which have been validated by a tandem mass spectrometry experiment, high-performance liquid chromatography/mass spectrometry analysis, and theoretical calculations. A full understanding of this reaction can contribute to the avoidance of analysis errors in the ESI-MS analysis of unknown heteroaromatic aldehydes.


Assuntos
Aldeídos/química , Artefatos , Hidrocarbonetos Aromáticos/química , Modelos Químicos , Espectrometria de Massas por Ionização por Electrospray/métodos
19.
Biomed Chromatogr ; 29(6): 860-8, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25408477

RESUMO

Ficus pandurata H. aerial roots are used as a traditional Chinese medicine for the treatment of uarthritis, indigestion and hyperuricemia. However, the bioactive constituents responsible for the pharmacological effects of F. pandurata H. are unclear. A simple and efficient HPLC/QTOF-MS/MS (high-performance liquid chromatography/electrospray ionization with quadrupole time-of-flight tandem mass spectrometry) method was established to detect and identify active constituents in the n-butanol extract of F. pandurata H. aerial roots. Chemical constituents were separated and investigated by HPLC/QTOF-MS/MS in the negative-ion mode. Thirty-seven compounds, including hydroxycinnamic acid derivatives, hydroxybenzoic acid derivatives, hydroquinone glycosides, flavonoid glycosides, etc., were identified or tentatively characterized in the n-butanol extract of F. pandurata H. aerial roots by comparing the UV spectra, accurate mass spectra and fragmentation pathways and retrieving the reference literatures. Moreover, the flavonoid trisaccharides and hydroxybenzoic acid derivatives were tentatively characterized in F. pandurata H. for the first time. The analytical tool used here is very valuable in the rapid separation and identification of the multiple and minor constituents in the n-butanol extract of F. pandurata H. aerial roots.


Assuntos
Ácidos Cumáricos/análise , Ficus/química , Flavonoides/análise , Glicosídeos/análise , Fenóis/análise , Raízes de Plantas/química , Cromatografia Líquida de Alta Pressão/métodos , Ácidos Cumáricos/química , Ácidos Cumáricos/isolamento & purificação , Flavonoides/química , Flavonoides/isolamento & purificação , Glicosídeos/química , Glicosídeos/isolamento & purificação , Fenóis/química , Fenóis/isolamento & purificação , Extratos Vegetais/química , Espectrometria de Massas em Tandem/métodos
20.
Anal Chim Acta ; 1328: 343172, 2024 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-39266195

RESUMO

BACKGROUND: The use of pesticides to protect crops has long been an important measure to provide healthy and safe agricultural products, but excess pesticides flow into fields and rivers, causing environmental pollution. Earlier methods utilizing organic solvent liquid-liquid microextraction for pesticide residue detection were not environmentally friendly. Therefore, it is significant to find a greener and more convenient detection method to determine pesticide residues. RESULTS: A new method was established to detect three triazole fungicides (TFs), including myclobutanil, epoxiconazole and tebuconazole, in environmental water samples. And the determination was conducted using a high-performance liquid chromatography with the ultraviolet detector (HPLC-UV). The switchable deep eutectic solvent (SDES) can be reversibly switched between hydrophilic and hydrophobic states through temperature modulation. Additionally, the method exhibited excellent linearity for all target analytes within the concentration range of 10-2000 µg L-1, with satisfactory R2 values (≥0.9975). The limits of detection (LODs) ranged from 2.3 to 2.6 µg L-1, and the limits of quantification (LOQs) ranged from 7.8 to 8.7 µg L-1. The accuracy of the method was assessed through intra-day and inter-day precision tests, yielding relative standard deviations (RSDs) in the ranges of 2.8%-6.7% and 2.2%-7.5%, respectively. Density functional theory (DFT) results indicated that hydrogen bonding is a significant factor affecting the binding of DES with triazoles. Three different green assessment tools were used to prove that the SDES-HLLME method had good greenness and broad applicability. SIGNIFICANCE: This is a homogeneous liquid-liquid microextraction (HLLME) method based on the upper critical solution temperature (UCST) type switchable deep eutectic solvent program, which can complete the extraction within a few minutes without dispersant. In terms of pesticide detection, the analytical method is simple and more conducive to environmental protection.

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