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1.
J Chromatogr A ; 1626: 461377, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797853

RESUMO

This study reports the use ofa natural deep eutectic solvent (NADES) with hollow fiber-microporous membrane liquid-liquid microextraction (HF-MMLLE) for the multiclass determination of 11 compounds classified as emerging contaminantsin water. Different deep eutectic solvents were synthetized and Thymol: Camphor (1:1 molar fraction) wasused as extraction solvent. The Thymol:Camphor was impregnated into the polypropylene membrane porous for 10 min, replacing commonly used solvents (ex. hexane and octanol). The optimized parameters were obtained by multi and univariate models. Extractions were carried out for 50 min using 1.5 mL of water sample at pH 6 and without addition of salt while desorption was made in a mixture of acetone: methanol (3:1, v/v) for 15 min. Separation/quantification was conducted by HPLC with a diode array detection (DAD)and calibration curves were obtained for each analyte. Determination coefficients higher than 0.9906 and limits of detection ranged from 0.3 to 6.1 µg L-1. Intraday precision (n = 3) ranged from 1.6 to 18.4% and inter day from 5.0 to 21.3%. Relative recoveries were performed in tap and stream water and ranged from 64 to 123%.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Microextração em Fase Líquida/métodos , Solventes/química , Poluentes Químicos da Água/análise , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Polipropilenos/química , Porosidade , Espectrofotometria , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/normas
2.
J Chromatogr A ; 1626: 461381, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797855

RESUMO

A reliable and sensitive analytical approach has been optimized for the extraction of seven polychlorinated biphenyls (PCBs) from human breast milk. Hollow fiber liquid phase microextraction (HF-LPME) was applied for the first time for the extraction and pre-concentration of the analytes. Analytes were separated by gas chromatography with electron capture detector (GC-µECD) for the sensitive detection and mass spectrometry for the unequivocal identification. A rotable central composite design (RCCD) was performed for the multivariate optimization of the method. The best results were obtained at 40 °C during 30 min and 600 rpm of stirring speed using a hollow fiber length of 5 cm and toluene as an extractant phase and salt addition was not required. The detection limits were in the range 7-14 ng L-1 for PCBs. The coefficients of determination of the calibration curves indicated good linearity (R2> 0.96) and the enrichment factors ranged from 74 to 143. This type of study is of great importance due to the deleterious effect that the presence of contaminants can produce in infants health related to the immature character of the defense system. Moreover, exclusive breastfeeding is recommended by neonatologists up to six months of life and as complementary food during the first two years.


Assuntos
Microextração em Fase Líquida/métodos , Leite Humano/química , Bifenilos Policlorados/análise , Cromatografia Gasosa , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Bifenilos Policlorados/isolamento & purificação , Porosidade , Reprodutibilidade dos Testes , Sais/química
3.
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
4.
Food Chem ; 332: 127395, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615385

RESUMO

This paper describes a simple, efficient and rapid analytical method for extraction and determination of nitrite in meat and chicken products by vortex-assisted supramolecular solvent-based liquid phase microextraction (VA-SUPRAS-LPME) prior to spectrophotometric detection. The SUPRAS was rapidly formed by the addition of a colloidal decanoic acid suspension to tetrahydrofuran (THF). The validation studies were carried out in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), matrix effects, robustness, uncertainty measurement, precision, accuracy, and certified reference material (CRM) analysis using optimized experimental conditions. The LOD, LOQ, linearity and matrix effect were 0.035 ng mL-1, 0.1 ng mL-1, 0.1-300 ng mL-1, and 9.6% respectively, with high preconcentration factor (200). The method was successfully applied for the determination of nitrite in processed products. Moreover, the results obtained by the proposed method were compared to the standard Griess method, and showed no significant differences in term of Student's t-test.


Assuntos
Galinhas , Análise de Alimentos/métodos , Microextração em Fase Líquida/métodos , Carne/análise , Nitritos/análise , Nitritos/isolamento & purificação , Solventes/química , Animais , Contaminação de Alimentos/análise , Manipulação de Alimentos , Química Verde , Humanos , Limite de Detecção , Espectrofotometria Ultravioleta
5.
Food Chem ; 332: 127371, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32622188

RESUMO

A simple and sensitive salting out-assisted dispersive liquid-liquid microextraction method using deep eutectic solvent combined with back extraction and micellar electrokinetic capillary chromatography (SO-DLLME-DES-BE-MECC) was developed for the determination of fluoroquinolones in milk, honey and water samples. Several parameters affecting the extraction efficiency including DES volume, vortex time, centrifugation time, salt type and amount, sample pH and volume, etc. were investigated. Good linearity were obtained for fluoroquinolones in a range of 0.020-3.200 µg mL-1 and 0.030-4.800 µg mL-1 with LODs less than 0.010 µg mL-1. The recoveries were in the ranges of 95.0-104.9%, 90.1-110.2% and 87.8-114.1% for water, honey and milk samples, respectively. The relative standard deviations for reproducibility were all below 7.6%. Under the optimized conditions, the enrichment factors for analytes were achieved in the range from 531 to 858 folds. The presented method was successfully applied for the determination of fluoroquinolones in milk, honey and water samples.


Assuntos
Cromatografia Capilar Eletrocinética Micelar , Fluoroquinolonas/análise , Mel/análise , Microextração em Fase Líquida/métodos , Leite/química , Solventes/química , Água/química , Animais , Fluoroquinolonas/química , Fluoroquinolonas/isolamento & purificação , Limite de Detecção , Sais/química
6.
J Chromatogr A ; 1625: 461295, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709338

RESUMO

In addition to the diverse extraction techniques available, capsule phase microextraction (CPME), which uses a microextraction capsule (MEC), has recently been introduced as a sorptive-based sample preparation technique. In this study, two different MECs (MEC-C18/SAX and MEC-C18/SCX) based on mixed-mode ion-exchange technology were synthesized and evaluated for the selective extraction of a group of ionizable compounds, including acidic and basic analytes. A sulfonic acid was used as the cation-exchange group in MEC-C18/SCX, and a quaternary amine as the anion-exchange group in MEC-C18/SAX. The extraction parameters optimized were sample pH, elution solvent, sample/elution volume and extraction/elution time. The optimized CPME method followed by LC-MS/MS was used to determine the ionizable compounds in environmental water samples, including river water and effluent wastewater, with excellent selectivity and matrix effect values below -30% (except -33% for mephedrone) and apparent recovery results ranging from 40% to 69%, except for ibuprofen (< 35%) and atenolol (< 25%). The analytical method was validated for environmental water samples, and used in the analysis of several samples in which some of the target compounds were found at ng L-1 concentration levels.


Assuntos
Microextração em Fase Líquida/métodos , Transição de Fase , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Cromatografia Líquida , Concentração de Íons de Hidrogênio , Reprodutibilidade dos Testes , Rios/química , Extração em Fase Sólida/métodos , Fatores de Tempo , Eliminação de Resíduos Líquidos , Águas Residuárias/química , Água/análise
7.
Food Chem ; 331: 127190, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32562982

RESUMO

Monitoring neonicotinoid residues in grains is of significant interest for the proper assessment of pesticide exposure to human. The quick, easy, cheap, effective, rugged, and safe extraction method combined with dispersive liquid-liquid micro-extraction (QuEChERS-DLLME) was developed for extracting, purifying, and concentrating seven common neonicotinoid pesticides from the grains (rice, millet, and maize). Water and acetonitrile were used in tandem as extractants in QuEChERS, while water, acetonitrile, and trichloromethane in DLLME acted as the external phase, dispersant, and extractant, respectively. Comprehensive consideration of the single factor test and response surface method to optimize parameters including type and volume of extractants and dispersant. The evaluation showed that the QuEChERS-DLLME method held excellent linearity (R2 > 0.99). The limits of quantitation ranged from 0.003 to 0.08 µg kg-1 for the seven insecticides. The recoveries were in the range of 62-118%, and good reproducibility was obtained with a relative standard deviation below 15%.


Assuntos
Grão Comestível/química , Contaminação de Alimentos/análise , Microextração em Fase Líquida/métodos , Neonicotinoides/análise , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Acetonitrilos/química , Cromatografia Líquida/métodos , Inseticidas/análise , Limite de Detecção , Oryza/química , Reprodutibilidade dos Testes , Zea mays/química
8.
J Chromatogr A ; 1623: 461204, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505292

RESUMO

Deep eutectic solvents (DESs) were used as an extractant for the determination of pyrethroids in environmental water and tea beverage samples. Three different acids were chosen as hydrogen bond donors for preparation of DESs, and decanoic acid was optimal because of its high recovery. Factors affecting relative recovery were optimized individually, including salt addition, surfactant addition, extraction temperature, DES amount, and sample volume etc. Under the optimized experimental conditions, the relative recovery of pyrethroids was from 89.3% to 97.7%, with relative standard deviation (RSD) values ranging from 1.75% to 2.73%. The linear correlation coefficient ranged from 0.9981 to 0.9992, and the linear range was between 1.9 and 500 µg/L. Based on a signal-to-noise ratio (S/N) of 3:1, the limit of detection (LOD) values were 0.56 to 1.24 µg/L. The enrichment factor ranged from 92 to 105. In conclusion, good extraction efficiency was achieved in tea beverage samples under the optimized conditions.


Assuntos
Bebidas , Emulsões/química , Interações Hidrofóbicas e Hidrofílicas , Microextração em Fase Líquida/métodos , Piretrinas/análise , Solventes/química , Chá/química , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Cloreto de Sódio/química , Tensoativos/química , Temperatura , Água/química
9.
Bull Environ Contam Toxicol ; 105(2): 332-336, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32556692

RESUMO

Since the Directive 2013/39/EU included terbutryn to the list of priority substances of all water bodies, a previous method based on dispersive liquid-liquid micro-extraction (DLLME) for the determination of triazines in seawater has been modified. The main change consisted on the use of tandem mass spectrometry instead of diode array as detection technique. Due to the higher sensitivity of mass detector, sample volume was reduced and extraction solvent volume was optimized. The optimum extraction conditions were 5 mL of sample, 50 µL of 1-octanol and an agitation step instead of disperser solvent. The obtained analytical recoveries (73%-101% with relative standard deviations below 4%) meeting the requirements. The limits of quantification (between 0.016 and 0.021 µg L-1) were more than 10 times lower than the limit set by the European Directive 2013/39/EU for terbutryn (0.34 µg L-1). The proposed method was applied to the determination of the target compounds in seawater samples from A Coruña (Galicia, NW of Spain).


Assuntos
Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Poluentes Químicos da Água/análise , Microextração em Fase Líquida/métodos , Água do Mar/química , Solventes/química , Espanha
10.
Food Chem ; 327: 126996, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32447134

RESUMO

This work describes a novel approach for the analysis of 11 phenolic compounds (naringenin, hesperetin, kaempferol, quercetin, epicatechin, epicatechin gallate, epigallocatechin gallate, genistein, daidzein, caffeic acid, gallic acid) in human milk. Clean-up of the sample and extraction of 11 analytes from milk was performed by dispersive liquid-liquid microextraction (DLLME). Under the optimal conditions, the extraction recoveries of 11 analytes were in a range from 94.3% to 108%. For determination of phenolic compounds in extracts, LC-ESI-MS/MS method was used. The calibration curves showed linearity in the concentration ranges from 0.01 to 1500 ng mL-1 and the limits of detection were in a range from 0.18 ng L-1 to 74 ng mL-1. The repeatability and intermediate precision expressed as the relative standard deviations were below 7.6% and 9.9%, respectively. The DLLME-LC-ESI-MS/MS method was successfully applied to the determination of phenolic compounds present in breast milk.


Assuntos
Cromatografia Líquida/métodos , Microextração em Fase Líquida/métodos , Leite Humano/química , Fenóis/análise , Espectrometria de Massas em Tandem/métodos , Calibragem , Feminino , Análise de Alimentos/métodos , Humanos , Polônia
11.
J Chromatogr A ; 1621: 461030, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32192705

RESUMO

In the present study, a new generation of water-immiscible natural deep eutectic solvents (DESs) was synthesized using borneol as a hydrogen-bonding acceptor and decanoic acid, oleic acid, and thymol as a hydrogen-bonding donor in different molar ratios. These green hydrophobic solvents which are chemically stable in aqueous solutions were used as extraction solvents for isolation and pre-concentration of warfarin in biological samples. In this method, fine droplets of DESs were dispersed into the sample solution by using the air-assisted liquid-liquid micro-extraction method to accelerate the cloudy emulsion system formation and increase the mass transfer of the analyte to the DES-rich phase. The borneol based deep eutectic solvent is a worthy generation of the extraction solvents in the ALLME method due to low-cost and less toxicity. A Plackett-Burman design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design (BBD). Optimized extraction conditions were pH of sample solution of 3.9, number of aspiration/dispersion cycles of 15, the volume of DES of 60 µL, and rate and time of centrifuge of 6000 rpm and 10 min, respectively. Under the optimized conditions, the developed NADES-ALLME method exhibited a wide linear range of 5-500 µg L - 1 for plasma and urine samples with satisfactory recoveries above 88.80%. Limit of detections (LODs) and Limit of quantifications (LOQs) of warfarin were in the ranges of 0.5-2.7 and 1.65-8.91, respectively. The enrichment factors were obtained in the range of 148-164 and precisions were lower than 5.87%. Finally, the proposed method was successfully employed for the analysis of warfarin in human urine and plasma samples.


Assuntos
Canfanos/química , Microextração em Fase Líquida/métodos , Solventes/química , Varfarina/análise , Varfarina/isolamento & purificação , Adulto , Ar , Ácidos Decanoicos/química , Feminino , Química Verde , Humanos , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Ácido Oleico/química , Solventes/síntese química , Timol/química , Varfarina/sangue , Varfarina/urina , Água/química
12.
Food Chem ; 319: 126583, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32187566

RESUMO

This study established a simple and rapid method for determination of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) by dispersive liquid-liquid micro-extraction coupled with high performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOF/MS) in white and red wines. Affecting variables, including extraction solvent, salt concentration, ultrasound-vortex conditions and ethanol content, were evaluated. Under optimized conditions, the limit of detection (LODs) for SCCPs and MCCPs were in the range of 0.15-3.00 ng mL-1 and 0.08-2.50 ng mL-1, respectively. The spiked recoveries of SCCPs and MCCPs from white and red wine ranged from 63.2% to 127%. The method is precise with intra- and inter-day variations within 14.0% and 17.0%, respectively. SCCPs and MCCPs in wines from china varied widely, from

Assuntos
Análise de Alimentos/métodos , Microextração em Fase Líquida/métodos , Parafina/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Vinho/análise , China , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Hidrocarbonetos Clorados/análise , Limite de Detecção , Parafina/química
13.
J Chromatogr A ; 1621: 461041, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32204878

RESUMO

The current study presents for the first time a combination of the gel electromembrane extraction (GEL-EME) and switchable hydrophilicity solvent-based homogeneous liquid-liquid microextraction (SHS-HLLME) methods which can be used as an efficient hyphenated extraction procedure. This coupled method, which was followed by GC-FID, was applied for quantification of antidepressants (desipramine, clozapine, and citalopram) in biological and wastewater samples. The effective parameters of both GEL-EME and SHS-HLLME procedures were optimized. Using an agarose gel membrane, analytes were extracted from 7.0 mL of the sample solution to 500 µL of the aqueous acceptor solution. The maximum extraction of analytes of interest was obtained under the optimized conditions (pH of acceptor solution, 5.0; pH of gel membrane, 5.0; pH of sample solution, 7.0, voltage value, 30 V; and extraction time, 30 min). Then, the acceptor solution was transferred to the extraction cell and the SHS-HLLME procedure was conducted again under the optimized conditions. Dipropylamine (50 µL) was selected as an extraction solvent. The introduced technique exhibited good linearities with coefficients of determinatin (R2) higher than 0.983 and an acceptable linear range of 5.0-1000 ng/mL. Accordingly, the limit of detection was ≤ 1.0 ng/mL (S/N = 3) for all analytes, and the high enrichment factors were obtained in the range of 178.7-194.8. Moreover, the corresponding repeatability was from 4.0 to 8.7% (n = 3). The proposed method was successfully utilized to determine trace levels of the drugs in human serum, wastewater, and breast milk samples.


Assuntos
Antidepressivos/análise , Cromatografia Gasosa , Microextração em Fase Líquida/métodos , Antidepressivos/sangue , Antidepressivos/isolamento & purificação , Géis , Humanos , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Leite Humano/química , Sefarose , Solventes/química , Águas Residuárias/química
14.
J Chromatogr A ; 1620: 461000, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32173026

RESUMO

This work focused on the development and validation of a method based on hollow fiber-based solid-phase microextraction coupled to ultra-performance liquid chromatography tandem mass spectrometry (HF-based-SPME-UPLC-MS/MS) for the determination of five antipsychotics at a pg mL-1 level in human whole blood and urine. Four types of hollow fiber membrane materials, including polyether sulfone, polypropylene, polyvinyl chloride and polyvinylidene fluoride were investigated. Finally, polyether sulfone hollow fiber without any modification was selected as the adsorption medium for solid-phase microextraction (SPME) with the following extraction procedure: the analytes were adsorbed onto the hollow fiber in the sample bottle with application of ultrasonication. Subsequently, the hollow fiber was transferred into a slim glass tube containing an appropriate solvent, and the analytes were desorbed by ultrasound treatment before detection by UPLC-MS/MS. In order to obtain satisfactory extraction efficiency, extraction parameters such as hollow fiber membrane material, pH, hollow fiber length, extraction time, desorption solvent and desorption time were investigated. Under the optimum experimental conditions, this method allowed for determination of five antipsychotics in human whole blood with excellent limits of quantification (LOQs) (25.0, 12.5, 25.0, 25.0 and 12.5 pg mL-1 for perphenazine, chlorpromazine, chlorprothixene, promethazine and trifluoperazine, respectively). The corresponding LOQs in human urine were 25.0, 12.5, 12.5, 12.5 and 12.5 pg mL-1 for the respective antipsychotics. The precision (RSD) was no more than 13.3%. The extraction recoveries for human whole blood and urine were in the range of 46.4-96.6% and 65.2-101.9%, respectively. The proposed method was compared with other methods from the literature and the results demonstrate that it is a simple, sensitive, efficient and green technique. It is suitable for analyzing trace target analytes in complex matrices such as biological samples and can provide a reliable tool for drug monitoring especially in forensic analysis and case of drug abuse.


Assuntos
Antipsicóticos/análise , Cromatografia Líquida/métodos , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Adsorção , Adulto , Antipsicóticos/sangue , Antipsicóticos/isolamento & purificação , Antipsicóticos/urina , Feminino , Humanos , Microextração em Fase Líquida/métodos , Polímeros/química , Reprodutibilidade dos Testes , Solventes , Sulfonas/química
15.
Food Chem ; 320: 126486, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32208186

RESUMO

A fast, simple, sensitive, and efficient vortex-assisted dispersive liquid-liquid microextraction method (VA-DES-DLME) was developed based on hydrophobic deep eutectic solvent for extraction of folic acid from flour samples followed by HPLC determination. Hydrophobic DES was prepared by mixing amylalcohol as a hydrogen bond donor and methyltriocthylammonium chloride as a hydrogen bond acceptor. Factors affecting DLLME were considered and optimized. In optimal conditions, the calibration curve was linear in the range 5.0-500 ng g-1 with a correlation coefficient higher than 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.0 and 3.0 ng g-1, respectively. The intra-day and inter-day precision at concentrations of 10 and 100 ng g-1 were less than 8%. Finally, application of the proposed procedure was investigated by folic acid analysis in flour samples and the relative recoveries obtained were acceptable (Recovery ≥ 90%).


Assuntos
Farinha/análise , Ácido Fólico/análise , Microextração em Fase Líquida/métodos , Cromatografia Líquida de Alta Pressão , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Solventes/química
16.
Food Chem ; 317: 126424, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32088405

RESUMO

In this study, a simple, efficient, and green effervescence tablet-assisted microextraction method based on the solidification of deep eutectic solvent (ETA-ME-SDES) was developed to determine picoxystrobin, pyraclostrobin, and trifloxystrobin in water, juice, wine, and vinegar samples by HPLC. An eco-friendly, hydrophobic, deep eutectic solvent (DES, acting as the extraction solvent) was synthesized by thymol and octanoic acid in the molar ratio of 1:5. The extraction solvent dispersed in sample solutions with the assistance of pH adjustment and effervescence reaction, and was collected after solidification in an ice bath. Several essential conditions, including the type and the volume of DESs, the amount of ammonia hydroxide, and the components of effervescence tablets were optimized. The limits of detection ranged from 0.15 to 0.38 µg L-1. Extraction recovery ranged from 77.4 to 106.9%. The proposed method was successful in determining the amount of strobilurin fungicides in water, juice, wine, and vinegar samples.


Assuntos
Ácido Acético/análise , Cromatografia Líquida de Alta Pressão , Sucos de Frutas e Vegetais/análise , Fungicidas Industriais/análise , Estrobilurinas/análise , Poluentes Químicos da Água/análise , Vinho/análise , Acetatos/análise , Fungicidas Industriais/química , Concentração de Íons de Hidrogênio , Iminas/análise , Limite de Detecção , Microextração em Fase Líquida/métodos , Sais/química , Estrobilurinas/química , Poluentes Químicos da Água/química
17.
J Chromatogr A ; 1619: 460929, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32008821

RESUMO

A simple, green and efficient method for extraction, purification and enrichment of pesticide residues of triazoles and pyrethroids in Longan fruit was developed by ultrasonic-assisted aqueous two-phase extraction (UAATPE) coupled to vortex-assisted dispersive liquid-liquid microextraction (VADLLME). Using an aqueous two-phase system (ATPS) of ethanol/K2HPO4 as extraction solvent, the composition of the ATPS, extraction temperature and time were investigated, respectively. Then VADLLME process also was optimized by investigating type and volume of extracting and dispersive solvents, vortex-assisted time and salt addition. The optimum conditions were as follows: the ATPS composition of ethanol concentration 30.0% (w/w) and K2HPO4 concentration 25% (w/w), extraction temperature 70 °C and extraction time 15 min for UAATPE; 1-dodecanol 200 µL as extraction solvent, ethanol 1.25 mL as dispersive solvent, vortex-assisted time 1.5 min and addition of NaCl 4% (w/v) for VADLLME. Ethanol as extraction solvent and dispersive solvent could directly connect UAATPE with VADLLME without extra steps. By means of HPLC-DAD detection, nine pesticides had good linearity ranged from 0.0200 to 13.59 µg/mL (R2 ≥ 0.9957). LODs and LOQs were in the range of 0.005576-0.01740 µg/mL and 0.01859-0.05010 µg/mL, respectively. UAATPE-VADLLME coupled to HPLC was successfully applied to simultaneous determination of multiple pesticides in Longan fruit, and mean recoveries and RSDs were between 76.95% and 98.63%, 1.2% and 9.8%, respectively. Furthermore, myclobutanil, fenpropathrin and deltamethrin were detected in pericarp and pulp of Longan samples from different districts, respectively.


Assuntos
Cromatografia Líquida de Alta Pressão , Análise de Alimentos/métodos , Frutas/química , Resíduos de Praguicidas/isolamento & purificação , Sapindaceae , Poluentes Químicos da Água/isolamento & purificação , Limite de Detecção , Microextração em Fase Líquida/métodos , Resíduos de Praguicidas/análise , Piretrinas/análise , Piretrinas/isolamento & purificação , Solventes/química , Triazóis/análise , Triazóis/isolamento & purificação , Ultrassom , Água/análise , Poluentes Químicos da Água/análise
18.
J Chromatogr A ; 1619: 460910, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32008827

RESUMO

A pH-sensitive polymer based on the poly(styrene-alt-maleic anhydride) co-polymer serves as basis to develop a microextraction method (pH-HGME) in direct combination with high-performance liquid chromatography (HPLC) and fluorescence detection (FD) for the determination of seven organic compounds, including three polycyclic aromatic hydrocarbons (PAHs), three monohydroxylated PAHs and one alkylphenol, in urine. The method bases on the structural modification of the pH-sensitive polymer in the aqueous sample at a high pH value, followed by the formation and insolubilization of a hydrogel containing the preconcentrated analytes by decreasing the pH, and the direct injection of the hydrogel-rich phase in the HPLC-FD system. The optimization of the main variables permitted the selection of low amounts of aqueous sample (10 mL), which was mixed with 10 mg of co-polymer also present in a low volume (150 µL) of concentrated NaOH. The method further requires the addition of 200 µL of concentrated HCl, 3 min of stirring, and 15 min of centrifugation. This pH-HGME-HPLC-FD method presented low limits of detection, ranging from 0.001 µg L-1 to 0.09 µg L-1 in ultrapure water, average relative recoveries of 96.9% for the concentration level of 0.60 µg L-1, and enrichment factors between 1.50 and 17.7. The proposed method also exhibited high precision, with intermediate relative standard deviations lower than 16% for a concentration level of 0.60 µg L-1. The developed pH-HGME-HPLC-FD method performed adequately when analyzing two human urine samples provided by a non-smoker male and a smoker female, respectively. One of the target analytes (2-hydroxynaphthalene) was quantified in both samples using the standard addition method, with a predicted concentration of 7.3 ± 0.4 µg L-1 in the non-smoker male urine and 19.3 ± 0.6 µg L-1 in the smoker female urine.


Assuntos
Cromatografia Líquida de Alta Pressão , Microextração em Fase Líquida/métodos , Maleatos/química , Hidrocarbonetos Policíclicos Aromáticos/urina , Poliestirenos/química , Feminino , Fluorescência , Humanos , Concentração de Íons de Hidrogênio , Masculino , Fenóis/urina , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação
19.
Anal Bioanal Chem ; 412(4): 933-948, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31927601

RESUMO

Deep eutectic solvents (DESs) were investigated as extracting solvent for headspace single-drop microextraction (HS-SDME). The extraction efficiency of 10 DESs mainly composed of tetrabutylammonium bromide (N4444Br) and long-chain alcohols was evaluated for the extraction of terpenes from six spices (cinnamon, cumin, fennel, clove, thyme, and nutmeg). The DES composed of N4444Br and dodecanol at a molar ratio of 1:2 showed the highest extraction efficiency and was selected to conduct the extractions of terpenes in the rest of the study. HS-SDME was optimized by design of experiments. Only two parameters from the four studied showed a significant influence on the efficiency of the method: the extraction time and the extraction temperature. The optimal extraction conditions were determined by response surface methodology. All extracts were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). More than 40 terpenes were extracted and identified in nutmeg, the richest extract in terpenes in this study. Quantitative analysis based on 29 standards was conducted for each extract. Good linearity was obtained for all standards (R2 > 0.99) in the interval of 1 to 500 µg/g. Limits of quantification ranged from 0.47 µg/g (borneol) to 86.40 µg/g (α-farnesene) with more than half of the values under 2 µg/g. HS-SDME is simple, rapid, and cheap compared with conventional extraction methods. The use of DESs makes this extraction method "greener" and it was shown that DESs can be suitable solvents for the extraction of bioactive compounds from plants.


Assuntos
Microextração em Fase Líquida/métodos , Especiarias/análise , Terpenos/análise , Cinnamomum zeylanicum/química , Cuminum/química , Foeniculum/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Myristica/química , Extratos Vegetais/química , Solventes/química , Syzygium/química , Terpenos/isolamento & purificação , Thymus (Planta)/química
20.
Environ Monit Assess ; 192(2): 72, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31897765

RESUMO

This study presents the use of Quick Easy Cheap Efficient Rugged and Safe (QuEChERS) as an effective sample cleaning procedure and switchable solvent liquid phase microextraction (SS-LPME) as a preconcentration tool for the determination of fenazaquin by gas chromatography mass spectrometry (GC-MS) at ultratrace levels. After a thorough optimization process, 0.50 mL of switchable solvent, 1.5 mL of 1.0 M sodium hydroxide, and 15 s of vortexing were determined as optimum conditions of the SS-LPME method. The limit of detection (LOD) and limit of quantitation (LOQ) determined using the optimum method (SS-LPME/GC-MS) were 0.05 and 0.18 ng/mL, respectively. Compared with direct GC-MS determination of fenazaquin, the optimum method yielded about 800-fold enhancement in detection power of GC-MS. The method was applied to lake, irrigation canal, well, and wastewater samples. In order to test the method's applicability on fresh tomato samples, a QuEChERS method was used before applying the SS-LPME method. Matrix-matched calibration standards were used to enhance the accuracy of fenazaquin quantification in spiked tomato samples to obtain recovery results close to 100%.


Assuntos
Lycopersicon esculentum/química , Quinazolinas/análise , Poluentes Químicos da Água/análise , Água/química , Monitoramento Ambiental/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Lagos/análise , Limite de Detecção , Microextração em Fase Líquida/métodos , Solventes/química , Águas Residuárias/química , Água/análise
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