Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 60
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Anal Bioanal Chem ; 411(1): 193-203, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30357441

RESUMO

Drugs of abuse and new psychoactive substances (NPS) for recreational purposes are in constant evolution, and their consumption constitutes a significant risk to public health and road safety. The development of an analytical methodology to confirm the intake of illicit drugs in biological fluids is required for an effective control of these substances. An ultra-performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS) was developed for simultaneous determination of 10 synthetic cathinones and 10 illicit drugs in oral fluid easily sampled through non-invasive maneuvers. The UPLC-MS/MS method was coupled to an ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME), which is a miniaturized and inexpensive technique that uses reduced volumes of solvents and samples. The US-DLLME was optimized by using a 213441//18 asymmetric screening design and a Doehlert design. Sample volume, dispersion and extraction solvent volumes, pH, US time, and amount of sodium chloride were evaluated. The US-DLLME-UPLC-MS/MS method was validated according to international guidelines. Limits of quantitation (LOQs) ranged from 0.25 to 5 ng mL-1, and the linear range spanned from LOQ to 500 ng mL-1 with R2 higher than 0.9907, for most of the target drugs. Precision ranged from 1.7 to 14.8 %RSD. Accuracy, i.e., extraction recovery, ranged from 74 to 129%. The proposed method was successfully applied to the analysis of 15 samples from patients on a drug detoxification program.


Assuntos
Drogas Ilícitas/análise , Microextração em Fase Líquida/métodos , Saliva/química , Ondas Ultrassônicas , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Padrões de Referência , Cloreto de Sódio/química , Solventes/química , Espectrometria de Massas em Tandem/métodos
2.
Anaesthesia ; 74(3): 340-347, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30666622

RESUMO

Proper placement of the tracheal tube requires confirmation, and the predominant method in addition to clinical signs is the presence of end-tidal carbon dioxide. Such is the importance of confirmation that novel methods may also have a place. We previously demonstrated using ex-vivo swine tissue a unique spectral reflectance characteristic of tracheal tissue that differs from oesophageal tissue. We hypothesised that this characteristic would be present in living swine tissue and human cadavers. Reflectance spectra in the range 500-650 nm were captured using a customised fibreoptic probe, compact spectrometer and white light source from both the trachea and the oesophagus in anesthetised living swine and in human cadavers. A tracheal detection algorithm using ratio comparisons of reflectance was developed. The existence of the unique tracheal characteristic in both in-vivo swine and cadaver models was confirmed (p < 0.0001 for all comparisons between tracheal and oesophageal tissue at all target wavelengths in both species). Furthermore, our proposed tracheal detection algorithm exhibited a 100% positive predictive value in both models. This has potential utility for incorporation into airway management devices.


Assuntos
Esôfago/diagnóstico por imagem , Intubação Intratraqueal/métodos , Traqueia/diagnóstico por imagem , Animais , Cadáver , Feminino , Tecnologia de Fibra Óptica , Humanos , Suínos
3.
J Appl Toxicol ; 35(4): 418-25, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25091865

RESUMO

Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine.


Assuntos
Cocaína/sangue , Drogas Ilícitas/sangue , Metadona/sangue , Morfina/sangue , Tratamento de Substituição de Opiáceos , Detecção do Abuso de Substâncias , Transtornos Relacionados ao Uso de Substâncias/sangue , Métodos Analíticos de Preparação de Amostras , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Cocaína/análogos & derivados , Cocaína/química , Humanos , Concentração de Íons de Hidrogênio , Drogas Ilícitas/química , Limite de Detecção , Microextração em Fase Líquida , Metadona/química , Metadona/uso terapêutico , Morfina/química , Derivados da Morfina/sangue , Derivados da Morfina/química , Fotometria , Reprodutibilidade dos Testes , Solubilidade , Espectrofotometria Ultravioleta , Transtornos Relacionados ao Uso de Substâncias/tratamento farmacológico , Ultrassom/métodos
4.
Anal Bioanal Chem ; 404(1): 173-81, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22638882

RESUMO

Chemical residues, such as insecticides and anthelmintics, are frequently redistributed from the aquatic environment to marine species. This work reports on a fast validated protocol for the analysis of azamethiphos, three avermectins, two carbamates and two benzoylurea pesticides and chemotherapeutic agents in seaweeds based on pressurized liquid extraction and separation of analytes by liquid chromatography coupled with tandem mass spectrometry. The variables affecting the efficiency of pressurized liquid extraction, including temperature, number of extraction cycles, static extraction time and percent acetonitrile flush volume, were studied using a Doehlert design. The optimum parameters were 100 °C and one cycle of 3 min with 70 % acetonitrile. Adequate in-cell clean-up of the seaweeds was achieved using 0.8 g of Florisil over 0.1 g of graphitized carbon black on the bottom of the cell. The optimized method was validated using an analyte-free seaweed sample fortified at different concentrations. The limits of quantification ranged from 3.6 µg kg(-1) (azamethiphos) to 31.5 µg kg(-1) (abamectin). The recovery was from 87 to 120 % in most cases at different spiking levels. Finally, the reproducibility of the method expressed as the relative standard deviation and evaluated at concentrations of 10 and 50 µg kg(-1) was in the range 9-14.3 % and 6.1-12.3 %, respectively. The applicability of the method was evaluated with five commercial and 12 wild edible seaweeds, and four target compounds were detected in two wild seaweeds at a concentration below the quantification limit.


Assuntos
Cromatografia Líquida/métodos , Contaminação de Alimentos/análise , Extração Líquido-Líquido/métodos , Praguicidas/análise , Alga Marinha/química , Praguicidas/isolamento & purificação , Espectrometria de Massas em Tandem/métodos
5.
Food Chem ; 384: 132530, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35227997

RESUMO

A new, fast, simple, and effective ultrasound-assisted dispersive liquid-liquid microextraction procedure (UA-DLLME) for the gas chromatography-mass spectrometry (GC-MS) determination of malondialdehyde, acrolein, and 4-hydroxy-2-nonenal in beverages was successfully developed. 2,4-Dinitrophenylhydrazine derivatization was performed during extraction. An asymmetrical 3541//18 screening design and a central composite surface response design were used to investigate the influence of the most critical factors during the extraction process (ultrasound time and temperature, extraction and disperser solvents volumes, salt addition, and derivatization reagent concentration). According to FDA guidelines, the method was validated, achieving good linearities with r2 ≥ 0.9982, recoveries between 94.0 and 102.4%, and reproducibility with RSD lower than 4.5%. The method was applied to simultaneously determine the compounds in 60 different beverage samples, including beer, coffee, black tea, and fruit juices. The presence of secondary lipid oxidation products is demonstrated in beverages with a strong roasting process or oxidation.


Assuntos
Microextração em Fase Líquida , Acroleína/análise , Aldeídos , Bebidas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limite de Detecção , Microextração em Fase Líquida/métodos , Malondialdeído/análise , Reprodutibilidade dos Testes
6.
J Pharm Biomed Anal ; 194: 113779, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33279303

RESUMO

The illicit market for new psychoactive substances (NPS) is continuously growing. Designer benzodiazepines (DBZD) and Z-hypnotics are increasingly being used for self-medication or recreational purposes. The limited regulation and little biological information available about NPS have raised the need for analytical methods capable of extracting and quantifying them in human biological fluids. In this work, a procedure based on microextraction by packed sorbent (MEPS) in combination with ultra-high performance liquid chromatography and tandem mass spectrometry (UHPLC-MS/MS) has been developed to determine the designer benzodiazepines (clonazolam, deschloroetizolam, nifoxipam, flubromazolam and meclonazepam), and the Z-hypnotics (zolpidem, zaleplon and zopiclone) in plasma. A 3342//16 asymmetric screening design was used to study extraction variables such as the type and volume of eluent, pH, number of extraction cycles, volume of washing solvent and type of sorbent. The ensuing analytical method was validated in terms of linearity by standard addition calibration curves at eight different analyte concentration levels from 0.5-500 ng mL-1. R2 values, limits of detection (LOD) and limits of quantification (LOQ) fell in the ranges 0.9900-0.9988, 0.5-5 ng mL-1 and 1-10 ng mL-1. Intra and interday precision expressed as relative standard deviations, were < 10.6 % and process efficiency ranged from 63 to 117 % for the quality control samples. The proposed method detected zolpidem and various other benzodiazepines in plasma samples from overdoses cases.


Assuntos
Hipnóticos e Sedativos , Espectrometria de Massas em Tandem , Benzodiazepinas/análise , Cromatografia Líquida de Alta Pressão , Drogas Desenhadas , Humanos , Limite de Detecção , Microextração em Fase Sólida
7.
Anal Bioanal Chem ; 398(2): 1005-16, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20652545

RESUMO

A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection gas chromatography-tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g(-1) and the limits of quantification were between 2.3 and 76.9 pg g(-1), far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed samples.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Praguicidas/análise , Alga Marinha/química , Extração em Fase Sólida/métodos , Cromatografia Gasosa-Espectrometria de Massas/economia , Limite de Detecção , Micro-Ondas , Praguicidas/isolamento & purificação , Extração em Fase Sólida/economia
8.
Anal Bioanal Chem ; 397(2): 677-85, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20204329

RESUMO

A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative to solid-phase extraction (SPE) for the determination of six benzodiazepines widely prescribed in European countries (alprazolam, bromazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma. For MAE optimization a Doehlert experimental design was used with extraction time, temperature and solvent volume as influential parameters. A desirability function was employed in addition to the simultaneous optimization of the MAE conditions. The analysis of variance showed that the solvent volume had a positive influence on the extraction of all the analytes tested, achieving a statistically significant effect. Also, the extraction time had a statistically significant effect on the extraction of four benzodiazepines. The selected MAE conditions-89 degrees C, 13 min and 8 mL of chloroform/2-propanol (4:1, v/v)-led to recoveries between 89.8 +/- 0.3 and 102.1 +/- 5.2% for benzodiazepines using a high performance liquid chromatography method coupled with diode-array detection. The comparison of MAE and SPE shows better results for MAE, with a lower number of steps in handling the sample and greater efficiency. The applicability of MAE was successfully tested in 27 plasma samples from benzodiazepine users.


Assuntos
Benzodiazepinas/sangue , Benzodiazepinas/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Micro-Ondas , Humanos
9.
J Chromatogr A ; 1618: 460843, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31928774

RESUMO

A rapid separation and quantitation of the stereoisomer amino sugars glucosamine, galactosamine, and mannosamine, along with muramic acid, is needed. These compounds, when their quantities are accurate, can be used to understand the origin and fate of natural organic matter (NOM) in the environment. These target molecules are biomarkers of fungi and bacteria and allow the deconvolution of microbial transformations and degradation of NOM in a wide variety of environmental matrices. Analytical methods applied to this suite of biomarkers are needed to understand carbon and nitrogen biogeochemistry with a changing global climate. Traditional separations of these analytes by gas chromatography require sample derivatization, as does reverse phase liquid chromatography. In contrast, ion chromatography can separate the analytes directly, but requires a separate analytical method to quantify muramic acid. In this work we present a direct analysis of all these molecules using hydrophilic liquid interaction chromatography. Solvent composition, buffer strength, pH, flow rate, and column temperature were optimized. The method can separate these four compounds and the biopolymeric precursor molecule N-acetylglucosamine in a single run in under 8 min with equivalent resolution to the best previously reported separations that did not require derivatization prior to analysis. Detection of the analytes was performed by both tandem and time-of-flight mass spectrometry. The method was assessed for its quantitative capabilities through i) peak area assignment, ii) check standards with ratios of the target analytes likely to be present in real samples, iii) an injection internal standard, and iv) quantitative analysis of real soil hydrolysates by external calibration and standard addition approaches. Across their expected analytical ranges the response for each analyte was highly linear with good accuracy (<25%) and precision (<15%) over three orders of magnitude. Detection limits of 20 µg L-1 were found for galactosamine and 5 µg L-1 for the remainder of the analytes, comparable to the majority of other methods reported in the literature. Overall, this new approach can directly and rapidly quantify amino sugars recovered in environmental hydrolysates.


Assuntos
Biomarcadores/análise , Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Espectrometria de Massas , Ácidos Murâmicos/análise , Ácidos Murâmicos/química , Calibragem , Concentração de Íons de Hidrogênio , Limite de Detecção , Padrões de Referência , Reologia , Solo/química , Solventes/química , Estereoisomerismo , Temperatura
10.
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 de Plantas/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
11.
Food Chem ; 270: 214-222, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30174037

RESUMO

During the industrial refining process of edible oils and the manufacture of oil-based foodstuff, contaminants such as 3-monochloropropanediol (3-MCPD) fatty acid diesters can be produced. One hundred samples of different edible oils and related fatty food purchased from local Spanish markets were analyzed to evaluate the occurrence of these contaminants. Data of seven 3-MCPD diesters together with corresponding total 3-MCPD equivalents are presented. The procedure is based on a modified QuEChERS protocol followed by LC-MS/MS analysis. Extra virgin olive oil (EVOO) and unrefined oils did not contain detectable levels of the target analytes. The highest levels of 3-MCPD diesters were found in palm oils, for 1,2-Dilinoleoyl-3-chloropropanediol (LILI) and 1-2-Bispalmitoyl-3-chloropropanediol (PAPA) with concentrations close to 10 mg kg-1 and in the lipid fraction of margarines (8.09, 3.77 and 3.72 mg kg-1 for LILI, PAPA and 1-Oleoyl-2-linoleoyl-3-chloropropanediol (OLLI), respectively).


Assuntos
Ésteres/química , Contaminação de Alimentos/análise , Óleos de Plantas/análise , Óleos de Plantas/química , Espectrometria de Massas em Tandem , alfa-Cloridrina
12.
J Chromatogr A ; 1548: 19-26, 2018 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-29555360

RESUMO

A fast and effective method using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach which includes partitioned liquid-liquid extraction (PLLE) and dispersive solid phase extraction (dSPE) clean-up step for the determination of seven 3-monochloropropane-1,2-diol (3-MCPD) fatty acid diesters in vegetable oils is developed and validated according to the Food and Drug Administration (FDA) guidelines. Due to the complexity of the matrices, combination of silica based sorbents (Silica Strong Anion Exchange (Si-SAX), Supel™ QuE Z-Sep+ (Z-Sep+) and Primary Secondary Amine (PSA) were tested for lipid removal. The effect of several experimental factors on the efficiency of the extraction procedure was studied by a screening design 3422//16 and a response surface Doehlert design. The separation and determination was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The method provided suitable linearity (r2 > 0.9960), precision (relative standard deviation (RSD) lower than 10%) and accuracy, in terms of recovery. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 10 to 20 µg kg -1 and from 25 to 50 µg kg-1, respectively. The recoveries at three spiking levels of 100, 250, and 500 µg kg-1 were over the range of 71.4-122.9% with RSD lower than 13%. The method was successfully applied in edible oils and fatty food samples. The results provide valuable information to assess the risk of exposure to these foodborne contaminants.


Assuntos
Cromatografia Líquida/métodos , Ésteres/análise , Extração Líquido-Líquido/métodos , Óleos de Plantas/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , alfa-Cloridrina/análise , Limite de Detecção , Margarina/análise , Reprodutibilidade dos Testes
13.
Chemosphere ; 67(7): 1453-62, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17123577

RESUMO

A useful tool based on a single-step extraction and clean-up procedure for the determination of 15 organohalogenated pollutants (including brominated flame retardants) in aquaculture samples, using aluminium oxide basic and acidic silica gel in the supercritical extraction cell followed by gas chromatography with electron capture detection or mass spectrometry has been developed. This effective clean-up step ensures a minimum of chromatographic difficulties related to complex matrix components such as aquaculture feed. The extraction procedure has been screened by a fractional factorial design for the preliminary statistically significant parameters. The factors selected were extraction temperature, pressure, static extraction time, dynamic extraction time and carbon dioxide flow rate. The Doehlert design, followed by a multicriteria decision-making strategy, was then performed in order to determine the optimum conditions for the two most significant factors: pressure (165 bar) and dynamic extraction time (27 min). Under optimal conditions, the procedure developed with GC-MS/MS provides an excellent linearity, detection (0.01-0.2 ng g(-1)) and quantification limits (0.05-0.8 ng g(-1)) for most of the analytes investigated. The feasibility of the proposed supercritical fluid extraction method was validated by analysing two reference materials and fish feed and shellfish samples with satisfactory results.


Assuntos
Aquicultura , Hidrocarbonetos Halogenados/análise , Poluentes Químicos da Água/análise , Ração Animal/análise , Animais , Cromatografia Gasosa , Cromatografia com Fluido Supercrítico , DDT/análogos & derivados , DDT/análise , Eletroquímica , Peixes/fisiologia , Retardadores de Chama/análise , Cromatografia Gasosa-Espectrometria de Massas , Resíduos de Praguicidas/análise , Bifenilos Policlorados/análise , Espanha
14.
Talanta ; 174: 454-461, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-28738608

RESUMO

The emergence in recent years of potentially dangerous new psychoactive substances (NPS) that are not under international control has led to the development of multi-analyte procedures for their unequivocal quantification. A fast ultra-performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS), in combination with a sample pretreatment based on microextraction by packed sorbent (MEPS), was for the first time used in this work for the simultaneous determination of NPS in oral fluid. This matrix is an effective alternative to typical biological samples for drug control in substitution therapy programs, and also for the prevention and reduction of traffic accidents. The proposed method allowed the separation and quantification of eleven synthetic cathinones, six opiates, scopolamine, cocaine and two metabolites in less than 3.0min by using appropriate isotope-labelled internal standards. The MEPS procedure, which is a miniaturized version of the SPE technique, is completed within 15min. The influence of variables such as the washing solution and eluent volumes, phase type, number of aspirate-dispense cycles and pH was investigated by using a 3441//16 asymmetric screening design and a response surface methodology based on a Doehlert design. The MEPS process performed optimally with a mixed-mode C8/SCX sorbent and a sample pH of 9. The proposed method was validated according to major guidelines and found to span the linear concentration range 0.5-500ngmL-1 (R2 ≥ 0.9903), and to be selective and precise (within- and between-day precision as %RSD were both lower than 13.7%). The accuracy, in terms of analyte extraction recovery, ranged from 75% to 125% for most of the analytes. The MEPS-UPLC-MS/MS method was successfully used to analyse twelve real samples from patients on a drug detoxification programme and proved an effective tool for drug monitoring.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Psicotrópicos/análise , Psicotrópicos/isolamento & purificação , Saliva/química , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Humanos , Limite de Detecção , Reprodutibilidade dos Testes , Solventes/química
15.
J Chromatogr A ; 1485: 8-19, 2017 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-28108082

RESUMO

A miniaturized and simple method based on digitally programmed microextraction by packed sorbent (eVol®-MEPS) coupled to ultra-performance liquid chromatography (UPLC) has been developed for quantitative determination of three synthetic cathinones and seven conventional drugs of abuse and metabolites. The influence of several extraction parameters, such as washing and elution solvents were tested. In addition important variables affecting MEPS performance, namely sample volume, sorbent drying time, washing solvent volume, elution volume, number of extraction cycles, sorbent phase and pH, were evaluated using an asymmetrical screening design. The optimal experimental conditions involved 300µL of plasma, loading 10×100µL of sample through a C8/SCX sorbent in a MEPS syringe placed in the semi-automatic eVol® system, washing using 150µL H2O:MeOH (90:10, v/v), drying for 0.5min and elution using 200µL dichloromethane:2-propanol:ammonium hydroxide (78:20:2, v/v/v). The drugs separation was achieved using an ACQUITY BEH Shield RP18 column (2.1mm×100mm×1.7µm) in 3min. Under optimized conditions the proposed method was validated in terms of selectivity, linearity, limits of detection (LOD) and quantitation (LOQ), precision and matrix effect, using standard addition calibration. The combination of MEPS and UPLC provides a method for the primary screening of the analytes in 18min with excellent recoveries at three concentration levels, ranging between 80 and 104% (relative standard deviation <11%). The developed methodology has been successfully applied to plasma samples from polydrug abusers.


Assuntos
Drogas Ilícitas/sangue , Psicotrópicos/sangue , Microextração em Fase Sólida/métodos , Detecção do Abuso de Substâncias/métodos , Calibragem , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida , Humanos , Limite de Detecção
16.
J Pharm Biomed Anal ; 124: 189-197, 2016 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-26955756

RESUMO

A simple Ultrasounds Assisted-Dispersive Liquid Liquid Microextraction (UA-DLLME) method is presented for the simultaneous determination of six second-generation antidepressants in plasma by Ultra Performance Liquid Chromatography with Photodiode Array Detector (UPLC-PDA). The main factors that potentially affect to DLLME were optimized by a screening design followed by a response surface design and desirability functions. The optimal conditions were 2.5 mL of acetonitrile as dispersant solvent, 0.2 mL of chloroform as extractant solvent, 3 min of ultrasounds stirring and extraction pH 9.8.Under optimized conditions, the UPLC-PDA method showed good separation of antidepressants in 2.5 min and good linearity in the range of 0.02-4 µg mL(-1), with determination coefficients higher than 0.998. The limits of detection were in the range 4-5 ng mL(-1). The method precision (n=5) was evaluated showing relative standard deviations (RSD) lower than 8.1% for all compounds. The average recoveries ranged from 92.5% for fluoxetine to 110% for mirtazapine. The applicability of DLLME/UPLC-PDA was successfully tested in twenty nine plasma samples from antidepressant consumers. Real samples were analyzed by the proposed method and the results were successfully submitted to comparison with those obtained by a Liquid Liquid Extraction-Gas Chromatography - Mass Spectrometry (LLE-GC-MS) method. The results confirmed the presence of venlafaxine in most cases (19 cases), followed by sertraline (3 cases) and fluoxetine (3 cases) at concentrations below toxic levels.


Assuntos
Antidepressivos/sangue , Ultrassom , Antidepressivos/isolamento & purificação , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Microextração em Fase Líquida , Reprodutibilidade dos Testes
17.
J Chromatogr A ; 1071(1-2): 93-8, 2005 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-15865179

RESUMO

An effective multiresidual method for the trace analysis of fifteen compounds from a diverse group of pesticides, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyl (PCBs) and polybrominated biphenyl (PBBs) in aquaculture feed is described. The analytical procedure is based on the matrix solid-phase dispersion (MSPD) of feed sample and subsequent elution with hexane. The MSPD process was evaluated using an asymmetrical experimental design 2(3)3(2)//9. Factors such as C18 sorbent amount, kind of adsorbents, solvent volume and elution mode were considered. The results suggest that the operational MSPD conditions are elution with pressure, 1 g of C18, basic alumina as adsorbent and 30 mL of hexane. The overall method including MSPD procedure and GC coupled to mass spectrometry (MS/MS) has been applied to several samples of aquaculture feed and marine species. Precision and accuracy of the analytical method were determined using the reference material from the International Atomic Energy Agency (IAEA-406), showing a good agreement to the referenced values.


Assuntos
Aquicultura , Bromo/química , Cloro/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/química
18.
J Chromatogr A ; 889(1-2): 185-93, 2000 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-10985550

RESUMO

A simultaneous microwave-assisted extraction-derivatization procedure was developed and optimized for methylmercury analysis from biological samples. The analyte was derivatized with sodium tetraphenylborate forming a more hydrophobic compound, methylphenylmercury, which was extractable in toluene. The microwave extraction-derivatization procedure was optimized using experimental design, 2(5-1) fractional factorial. This chemometrical approach considers main effects as well as interactions of the influential parameters, indicating that temperature and its interaction with NaBPh4 and acetic acid volumes were the variables that significantly affected methylmercury recoveries.


Assuntos
Compostos de Metilmercúrio/isolamento & purificação , Calibragem , Técnicas de Laboratório Clínico , Micro-Ondas , Padrões de Referência , Reprodutibilidade dos Testes , Alimentos Marinhos/análise
19.
J Chromatogr A ; 1056(1-2): 179-85, 2004 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-15595548

RESUMO

A solvent-free method for the determination of five estrogens in water samples at the low ng/l was optimized. Compounds were first concentrated on a polyacrylate (PA) solid-phase microextraction (SPME) fiber, directly exposed to the water sample, and then on-fiber silylated on the headspace of a vial containing 50 microl of N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). Derivatized analytes were determined using GC with MS/MS detection. Influence of several factors on the efficiency of the microextraction step (e.g. time, sample volume, pH, ionic strength and fiber coating) is systematically described. Derivatization conditions were optimized in order to achieve the complete silylation of all hydroxyl groups contained in the structure of the compounds. Detection limits (from 0.2 to 3 ng/l) are compared with those obtained using the same detection technique and different sample preparation strategies, such as solid-phase extraction followed by silylation of the analytes in the organic extract and SPME without derivatization. The method was applied to the analysis of sewage water samples. Two of the investigated species were detected above the quantification limits of the procedure.


Assuntos
Estrogênios/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ácido N-Acetilneuramínico/análise , Poluentes Químicos da Água/análise , Concentração de Íons de Hidrogênio , Sensibilidade e Especificidade , Cloreto de Sódio/química
20.
J Chromatogr A ; 985(1-2): 265-74, 2003 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-12580494

RESUMO

A procedure is described for the determination of five acidic non-steroidal anti-inflammatory pharmaceuticals (ibuprofen, naproxen, ketoprofen, tolfenamic acid and diclofenac) in sewage water. The analytical method involves the concentration of water samples using a solid-phase extraction polymeric sorbent, functionalized with N-vinylpyrrolidone. Analytes were eluted with ethyl acetate. derivatized using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and analyzed by GC-MS. Influence of time, temperature and volume of MTBSTFA in the yield of the derivatization step were studied in detail using a factorial central composite design. Quantification limits of the analytical procedure for 500 ml of sewage water ranged from 20 to 50 ng/l. Recoveries from 90 to 115% were found for sewage water samples spiked with the studied compounds at the low ng/ml level. Results obtained for real samples show the presence of ibuprofen and naproxen in both influent and effluent of a sewage water treatment plant.


Assuntos
Anti-Inflamatórios não Esteroides/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Esgotos/química , Poluentes Químicos da Água/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA