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1.
Environ Monit Assess ; 196(5): 454, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38622372

RESUMO

This work presents a sensitive and accurate analytical method for the determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry (GC-MS) after the metal sieve-linked double syringe liquid-phase microextraction (MSLDS-LPME) method. A metal sieve was produced in our laboratory in order to disperse water-immiscible extraction solvents into aqueous media. Univariate optimization studies for the selection of proper extraction solvent, extraction solvent volume, mixing cycle, and initial sample volume were carried out. Under the optimum MSLDS-LPME conditions, mass-based dynamic range, limit of quantitation (LOQ), limit of detection (LOD), and percent relative standard deviation (%RSD) for the lowest concentration in calibration plot were figured out to be 100.5-10964.2 µg kg-1, 150.6 µg kg-1, 45.2 µg kg-1, and 9.4%, respectively. Detection power was improved as 187.7-folds by the developed MSLDS-LPME-GC-MS system while enhancement in calibration sensitivity was recorded as 188.0-folds. In the final step of this study, the accuracy and applicability of the proposed system were tested by matrix matching calibration strategy. Percent recovery results for domestic wastewater and synthetic urine samples were calculated as 95.6-110.3% and 91.7-106.6%, respectively. These results proved the accuracy and applicability of the proposed preconcentration method, and the obtained analytical results showed the efficiency of the lab-made metal sieve apparatus.


Assuntos
Microextração em Fase Líquida , Poluentes Químicos da Água , Cromatografia Gasosa-Espectrometria de Massas/métodos , Águas Residuárias , Fenitoína/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental/métodos , Solventes/química , Água/análise , Microextração em Fase Líquida/métodos , Limite de Detecção
2.
Anal Methods ; 16(9): 1363-1370, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38345087

RESUMO

Pesticides have been used on several fruits, vegetables and cereals to control harmful organisms in order to increase the quality of products; however, these substances cause serious health effects. Therefore, an accurate and sensitive analytical method should be developed for the determination of pesticides to evaluate their toxicity. In this study, an efficient microextraction strategy was applied to preconcentrate eight different selected pesticides from mixed fruit juice samples prior to gas chromatography-mass spectrometry detection. All significant parameters such as spraying number, extraction solvent type, sample volume and mixing type/period belonging to the developed extraction method were elaborately optimized to get low detection limits. After the optimization studies, system analytical performance studies were carried out and limit of detection (LOD) values varied from 0.04 µg /kg-1 to 1.99 µg kg-1 (mass based) for the selected analytes. Under the optimum experimental conditions, spiking recovery experiments were performed in the mixed fruit juice samples to evaluate the applicability and accuracy of the proposed method. The recovery results were recorded in the range of 81.4-123.5% with acceptable standard deviations by applying a matrix matching calibration strategy. The proposed analytical method can be used for the qualitative and quantitative determination of selected pesticides in the mixed fruit juice samples and can also be applied to other fruit juice samples using a matrix matching calibration strategy.


Assuntos
Praguicidas , Praguicidas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Calibragem , Sucos de Frutas e Vegetais/análise , Solventes
3.
Food Chem ; 439: 138140, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38061298

RESUMO

Rose tea infusion has gained popularity worldwide due to its health benefits. However, it is known that tea plants can be contaminated with heavy metals including copper. Hence, an accurate and applicable analytical method namely emulsification liquid-liquid microextraction based deep eutectic solvent - flame atomic absorption spectrometry (ELLME-DES-FAAS) was proposed to determine copper at trace levels in rose tea samples. Under the optimum experimental conditions, analytical figures of merit for the developed method were examined, and dynamic range, limit of detection (LOD) and limit of quantification (LOQ) were found to be 5.07-246.61 µg/kg (mass-based) with 0.9992 coefficient of determination, 2.50 µg/kg and 8.32 µg/kg, respectively. A matrix matching calibration strategy was employed to boost recovery results, and the acceptable recovery results were recorded between 95.9 % and 118.4 %. According to recovery results, the developed analytical method can be safely employed to determine the concentration of copper in rose tea samples accurately.


Assuntos
Microextração em Fase Líquida , Poluentes Químicos da Água , Cobre/análise , Microextração em Fase Líquida/métodos , Espectrofotometria Atômica/métodos , Análise de Alimentos/métodos , Solventes/química , Limite de Detecção , Chá/química , Poluentes Químicos da Água/análise
4.
Nanoscale ; 15(48): 19423-19447, 2023 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-38018389

RESUMO

Despite the many benefits derived from the unique features and practicality of nanoparticles, the release of their toxic by-products or products from the synthesis stage into the environment could negatively impact natural resources and organisms. The physical and chemical methods for nanoparticle synthesis involve high energy consumption and the use of hazardous chemicals, respectively, going against the principles of green chemistry. Biological methods of synthesis that rely on extracts from a broad range of natural plants, and microorganisms, such as fungi, bacteria, algae, and yeast, have emerged as viable alternatives to the physical and chemical methods. Nanoparticles synthesized through biogenic pathways are particularly useful for biological applications that have high concerns about contamination. Herein, we review the physical and chemical methods of nanoparticle synthesis and present a detailed overview of the biogenic methods used for the synthesis of different nanoparticles. The major points discussed in this study are the following: (1) the fundamentals of the physical and chemical methods of nanoparticle syntheses, (2) the use of different biological precursors (microorganisms and plant extracts) to synthesize gold, silver, selenium, iron, and other metal nanoparticles, and (3) the applications of biogenic nanoparticles in diverse fields of study, including the environment, health, material science, and analytical chemistry.


Assuntos
Nanopartículas Metálicas , Nanoestruturas , Bactérias/química , Nanoestruturas/química , Fungos/química , Fungos/metabolismo , Prata/química , Ferro/metabolismo , Nanopartículas Metálicas/química , Extratos Vegetais/química , Química Verde
5.
J Pharm Biomed Anal ; 217: 114855, 2022 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-35636012

RESUMO

A novel nebulizer interface (NI) was proposed to combine high performance liquid chromatography (HPLC) and flame atomic absorption spectrophotometer (FAAS). A glass concentric nebulizer was linked to T-shaped slotted quartz tube (T-SQT) using a tubing to transfer the liquid solution eluted from the chromatographic system into the atomization region of FAAS system. T-SQT was also used to intensify the interaction of atoms with the hollow cathode lamp light. Vitamin B12 was selected as an analyte to show the applicability of the new hyphenated system. After optimizing some parameters such as mobile phase flow rate and pH, nebulizer gas flow rate, T-SQT height and injection volume, linear range for the analyte was determined between 4.7 and 92 mg/kg as Co. Limit of detection (LOD) and limit of quantitation (LOQ) for the HPLC-NI-T-SQT-FAAS system were calculated to be 1.6 and 5.3 mg/kg as Co, respectively. Recovery studies were also conducted to verify the accuracy and applicability of the developed method for vitamin tablets and excellent percent recovery results (~ 100%) with low standard deviation values were obtained when matrix-matching calibration strategy was performed for each vitamin tablet. A successful separation and detection of the analyte was achieved within 3.0 min that offers high sample throughput. Two different vitamin tablets were analyzed by the optimized hyphenated system. The developed method also provides low usage of sample solution in contrast to conventional nebulizer in the FAAS system.


Assuntos
Microextração em Fase Líquida , Quartzo , Cromatografia Líquida de Alta Pressão , Microextração em Fase Líquida/métodos , Nebulizadores e Vaporizadores , Quartzo/química , Espectrofotometria Atômica/métodos , Vitamina B 12/análise , Vitaminas/análise
6.
Rapid Commun Mass Spectrom ; 36(12): e9282, 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35229402

RESUMO

RATIONALE: A derivatization switchable solvent liquid-liquid microextraction quadruple isotope dilution gas chromatography mass spectrometry (D-SS-LLME-ID4 -GC/MS) method is presented for the determination of hydroxychloroquine sulfate in human biofluids. METHODS: While mixing type/period and concentration of NaOH were optimized via a univariate optimization approach, a multivariate optimization approach was used to determine optimum values for relatively more important parameters such as volumes of derivatization agent (acetic anhydride), NaOH and switchable solvent. RESULTS: Under the optimum experimental conditions, limit of detection and limit of quantification were calculated as 0.03 and 0.09 mg/kg (mass based), respectively. An isotopically labelled material (hydroxychloroquine methyl acetate-d3 ) was firstly synthesized to be used in ID4 experiments which give highly accurate and precise recovery results. After the application of D-SS-LLME-ID4 , superior percent recovery results were recorded as 99.9 ± 1.6-101.3 ± 1.2 for human serum, 99.9 ± 1.7-99.8 ± 1.8 for urine and 99.6 ± 1.5-101.0 ± 1.1 for saliva samples. CONCLUSIONS: The developed D-SS-LLME-ID4 -GC/MS method compensates the complicated matrix effects of human biofluids and provides highly accurate quantification of an analyte with precise results.


Assuntos
Microextração em Fase Líquida , Acetatos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Hidroxicloroquina , Isótopos , Limite de Detecção , Microextração em Fase Líquida/métodos , Hidróxido de Sódio , Solventes/química
7.
J Chromatogr A ; 1667: 462870, 2022 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-35176687

RESUMO

The determination of amino acids in biological samples is central to the diagnosis of inherited metabolic disorders and also gives significant information about the metabolisms in the cells and living body. The development of analytical method for reliable quantification of amino acids in biological samples is still challenging because of the polar nature of amino acids and complex nature of biological samples causing a high degree of interferences during analysis. In the present study, a pre-column derivatization method using 2-naphtoyl chloride combined with liquid chromatography-tandem mass spectrometry method was developed for the determination of 17 amino acids in human serum and urine matrices. Low detection limits were obtained in the range of 0.015 - 0.266 µmol kg-1 and acceptable recovery results were obtained in human serum and urine samples. Isotopically labelled (15N labelled) amino acids were spiked to standards and samples before derivatization to compensate for the analytical errors in the whole procedure. The combination of quadrupole isotope dilution strategy with the derivatization based reversed phase chromatography allowed to improve method accuracy and precision.


Assuntos
Aminoácidos , Espectrometria de Massas em Tandem , Aminoácidos/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa , Humanos , Isótopos , Naftalenos , Espectrometria de Massas em Tandem/métodos
8.
Crit Rev Anal Chem ; 52(6): 1370-1385, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33576246

RESUMO

Sample preparation methods have become indispensable steps in analytical measurements not only to lower the detection limit but also to eliminate the matrix effect although more sophisticated instruments are being commonly used in routine analyses. Solid phase extraction (SPE) is one of the main extraction/preconcentration methods used to extract and purify target analytes along with simple and rapid procedures but some limitations have led to seek for an easy, sensitive and fast extraction methods with analyte-selective sorbents. Nanoparticles with different modifications have been used as spotlight to enhance extraction efficiency of target pesticides from complicated matrices. Carbon-based, metal and metal oxides, silica and polymer-based nanoparticles have been explored as promising sorbents for pesticide extraction. In this review, different types of nanoparticles used in the preconcentration of pesticides in various samples are outlined and examined. Latest studies in the literature are discussed in terms of their instrumental detection, sample matrix and limit of detection values. Novel strategies and future directions of nanoparticles used in the extraction and preconcentration of pesticides are also discussed.


Assuntos
Nanopartículas , Praguicidas , Praguicidas/análise , Dióxido de Silício , Extração em Fase Sólida/métodos
9.
J Pharmacol Toxicol Methods ; 113: 107130, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34688871

RESUMO

In the present study, a novel analytical method for the determination of hydroxychloroquine sulfate in human serum and urine samples was established. One step derivatization and dispersive liquid-liquid microextraction (DLLME) was developed for quantitative determination of hydroxychloroquine sulfate in aqueous samples. Hydroxychloroquine sulfate was first hydrolyzed and converted to its benzoate derivative by adding benzoyl chloride in chloroform which also served as extraction solvent. Significant parameters such as type/volume of extraction and dispersive solvents, concentration/volume of sodium hydroxide, type/period of mixing and concentration of derivatizing agent were carefully optimized by one variable at a time approach. Under the optimum DLLME conditions, limit of detection (LOD), quantitation (LOQ) and dynamic range were calculated as 35.2, 117.2 and 96-1980 µg/kg (ppb), respectively. Recovery studies were conducted by spiked human serum and urine samples and the results were ranged between 93 and 107% with low standard deviations. Developed method can be easily used in hydroxychloroquine sulfate based SARS-CoV-2 and malaria treatment studies.


Assuntos
Tratamento Farmacológico da COVID-19 , Microextração em Fase Líquida , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Hidroxicloroquina , Limite de Detecção , SARS-CoV-2 , Solventes
10.
J Chromatogr A ; 1651: 462273, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34087718

RESUMO

This study presents an accurate and precise analytical strategy for the determination of chloroquine phosphate at trace levels in human body fluids (urine, serum, and saliva). Simultaneous derivatization-spraying based fine droplet formation-liquid phase microextraction (SD-SFDF-LPME) method was used to derivatize and preconcentrate the analyte prior to gas chromatography-mass spectrometry (GC-MS) measurements. Acetic anhydride was employed as derivatizing agent in this study. After optimizing the SD-SFDF-LPME method, the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.16 and 0.53 mg/kg, respectively. Quadruple isotope dilution (ID4) was coupled to the SD-SFDF-LPME method in order to alleviate matrix effects and promote accuracy/precision of the method. Chloroquine acetamide-d3 was firstly synthesized in our research laboratory and used as the isotopic analogue of the analyte in the ID4 experiments. Superior percent recovery results (99.4% - 101.0%) with low standard deviation values were obtained for the spiked samples. This validated the developed SD-SFDF-LPME-ID4-GC-MS method as highly accurate and precise for the determination of chloroquine phosphate at trace levels. In addition, the isotopic analogue of the analyte was obtained via the acetamide derivative of the analyte, which is an alternative to obtain isotopic analogues of organic compounds that are not accessible or commercially available.


Assuntos
Cloroquina/análogos & derivados , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Líquida/métodos , Líquidos Corporais/química , Cloroquina/análise , Cloroquina/sangue , Cloroquina/isolamento & purificação , Cloroquina/urina , Humanos , Isótopos , Limite de Detecção , Saliva/química
11.
J Sep Sci ; 44(16): 3031-3040, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34102001

RESUMO

A new and efficient reversed-phase high-performance liquid chromatography-inductively coupled plasma-optical emission spectrometry method was developed for the simultaneous separation and determination of SeO3 2- and seleno-dl-methionine in kefir grains. For the system, limits of detection and quantitation values for SeO3 2- and seleno-dl-methionine were calculated as 0.52/1.73 mg/kg (as Se) and 0.26/0.87 mg/kg (as Se), respectively. After performing the system analytical performance, recovery experiment was done for kefir grains and percent recovery results for SeO3 2- and seleno-dl-methionine were calculated as 98.4 ± 0.8% and 93.6 ± 1.0%, respectively. It followed by the feeding studies that the kefir grains were exposed to three different concentrations of SeO3 2- (20, 30, and 50 mg/kg) for approximately 4 days at room temperature to investigate the conversion/non-conversion of SeO3 2- to seleno-dl-methionine. Next, the fed grains were extracted with tetramethylammonium hydroxide pentahydrate solution (20%, w/w) and then sent to the developed system. There was no detectable seleno-dl-methionine found in fed kefir grains at different concentrations of SeO3 2- while inorganic or elemental selenium in the fed kefir grains was determined between 1579.5 - 3116.0 mg/kg (as Se). Selenium species in the kefir grains samples was found in the form of SeO3 2- proved by using an anion exchange column.


Assuntos
Análise de Alimentos/métodos , Kefir/análise , Ácido Selenioso/análise , Selenometionina/análise , Antioxidantes , Técnicas de Química Analítica , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Desenho de Equipamento , Limite de Detecção , Selênio , Espectrofotometria/métodos
12.
Anal Sci ; 37(10): 1433-1438, 2021 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-33867401

RESUMO

A novel extraction method named hydrogen fluoride assisted-glass surface etching based liquid phase microextraction (HF-GSE-LPME) was proposed to determine 4-n-nonylphenol at trace levels by gas chromatography-mass spectrometry (GC-MS). After the evaluation of system analytical performance for the HF-GSE-LPME-GC-MS system, limit of detection (LOD) and limit of quantification (LOQ) values were calculated as 7.1 and 23.8 ng/g, respectively. Enhancement in detection power of the method was determined to be 22 fold when LOD values of the GC-MS and HF-GSE-LPME-GC-MS systems were compared with each other. Applicability and accuracy of the established method were checked by performing spiking experiments. A matrix matching calibration strategy was applied to boost the accuracy of quantification in both matrices, and the percent recovery results obtained for bottled drinking water and dam lake water samples were in the range of 98 - 107 and 90 - 117%, respectively.

13.
J Pharm Anal ; 11(3): 278-283, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33552628

RESUMO

A rapid, accurate, and sensitive analytical method, ultrasonication-assisted spraying based fine droplet formation-liquid phase microextraction-gas chromatography-mass spectrometry (UA-SFDF-LPME-GC-MS), was proposed for the determination of trace amounts of hydroxychloroquine sulfate in human serum, urine, and saliva samples. To determine the best extraction strategy, several liquid and solid phase extraction methods were investigated for their efficiencies in isolation and preconcentration of hydroxychloroquine sulfate from biological matrices. The UA-SFDF-LPME method was determined to be the best extraction method as it was operationally simple and provided accurate results. Variables such as the extraction solvent, spraying number, sodium hydroxide concentration and volume, sample volume, mixing method, and mixing period were optimized for the proposed method using the one-variable-at-a-time approach. In addition, Tukey's method based on a post hoc comparison test was employed to evaluate the significant difference between the parameters inspected. After the optimization studies, the limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.7 and 2.4 µg/kg, respectively. The sensitivity of the GC-MS system based on the LOD was enhanced approximately 440-fold when the UA-SFDF-LPME method was employed. Spiking experiments were also conducted for the human serum, urine, and saliva samples to determine the applicability and accuracy of the proposed method. Recoveries for the human serum, urine, and saliva samples were found to be in the ranges of 93.9%-101.7%, 95.2%-105.0%, and 93.1%-102.3%, respectively. These results were satisfactory and indicated that the hydroxychloroquine sulfate level in the above biological samples could be analyzed using the proposed method.

14.
J Pharmacol Toxicol Methods ; 108: 106949, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33503487

RESUMO

A vortex assisted spraying based fine droplet formation liquid phase microextraction (VA-SFDF-LPME) method was developed to determine chloroquine phosphate at trace levels in human serum, urine and saliva samples by gas chromatography-mass spectrometry (GC-MS) with single quadrupole mass analyzer. In the first part, several liquid phase microextraction (LPME) and magnetic solid phase extraction (MSPE) methods were compared to each other in order to observe their extraction ability for the analyte. VA-SFDF-LPME method was selected as an efficient and easy extraction method due to its higher extraction efficiency. Optimization studies were carried out for the parameters such as extraction solvent type, sodium hydroxide volume/concentration, sample volume, spraying number and mixing type/period. Tukey's method based on post hoc test was applied to all experimental data for the selection of optimum values. Optimum extraction parameters were found to be 12 mL initial sample volume, two sprays of dichloromethane, 0.75 mL of 60 g/kg sodium hydroxide and 15 s vortex. Under the optimum conditions, limit of detection and quantification (LOD and LOQ) were calculated as 2.8 and 9.2 µg/kg, respectively. Detection power of the GC-MS system was increased by approximately 317 folds with the developed extraction/preconcentration method. The applicability and accuracy of the proposed method was evaluated by spiking experiments and percent recovery results for human urine, serum and saliva samples were found in the range of 90.9% and 114.0% with low standard deviation values (1.9-9.4).


Assuntos
Cloroquina , Microextração em Fase Líquida , Cloroquina/análogos & derivados , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Limite de Detecção , Saliva
15.
Food Chem ; 340: 127945, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32889200

RESUMO

This study proposed a novel analytical method for the separation and determination of cobalamin and cobalt in kefir samples by high performance liquid chromatography-inductively coupled plasma-optical emission spectrometry (HPLC-ICP-OES) in addition to determination of cobalamin in HPLC system. Chromatographic parameters such as column type, buffer solution, mobile phase flow rate and sample injection volume were individually studied and optimized. In addition, cobalamin was simultaneously determined by high performance liquid chromatography with ultraviolet detection (HPLC-UV). LOD values of cobalt in cobalamin and cobalt for HPLC-ICP-OES system were calculated as 0.07 mg/kg (as Co) and 0.06 mg/kg, respectively. Recovery studies were conducted to evaluate the accuracy/applicability of the method. Recovery results for cobalt in cobalamin and cobalt detected by the HPLC-ICP-OES system were calculated in the range of 87.4-100.1 and 98.8-115.0%, respectively while recovery results for cobalamin were found to be between 89.2 and 98.3% for HPLC-UV system.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Vitamina B 12/análise , Cobalto/análise , Fatores de Tempo , Vitamina B 12/química
16.
J Mass Spectrom ; 55(10): e4622, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33210452

RESUMO

A novel, ecofriendly, and easy extraction and preconcentration method named as vortex-assisted spraying-based fine droplet formation liquid-phase microextraction was proposed for the determination of prochloraz at trace levels in orange juice samples by gas chromatography-mass spectrometry (GC-MS). In this novel system, extraction solvent is dispersed by the help of spraying apparatus instead of dispersive solvent. Various parameters of the method were carefully optimized to increase signal-to-noise ratio of the analyte. Under the optimum chromatographic and extraction conditions, limit of detection and limit of quantification were calculated as 3.2 and 10.8 µg/kg, respectively. Moreover, enhancement in quantification power for the GC-MS system was determined as 372 folds based on LOQ comparison. Relative recovery results for orange juice samples were found to be between 95.0-107.7% by utilizing matrix matching calibration. Furthermore, the developed method may be used to efficiently and simply extract other organic compounds for their determinations in several matrices.


Assuntos
Citrus sinensis/química , Sucos de Frutas e Vegetais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Imidazóis/análise , Imidazóis/isolamento & purificação , Limite de Detecção , Modelos Lineares , Microextração em Fase Líquida , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/isolamento & purificação , Reprodutibilidade dos Testes
17.
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
18.
Biomed Chromatogr ; 34(10): e4915, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32529647

RESUMO

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA-SHS-LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA-SHS-LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 µg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 µg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97-100% for human plasma and urine samples spiked at five different concentrations.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Oxcarbazepina/sangue , Oxcarbazepina/urina , Humanos , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Modelos Lineares , Oxcarbazepina/química , Reprodutibilidade dos Testes , Solventes/química
19.
Talanta ; 213: 120846, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200932

RESUMO

A novel derivatization method for the determination of propineb by gas chromatography-mass spectrometry (GC-MS) was developed in this study. This was achieved by isothiocyanate derivatization of the analyte by potassium persulfate and potassium carbonate in water medium. Dispersive liquid-liquid microextraction (DLLME) was employed to isolate and preconcentrate the derivatized analyte into an organic phase. All method parameters including concentration/volume of potassium persulfate and potassium carbonate salts, type/period of mixing for derivatization reaction and microextraction process were systematically optimized to lower the detection limit. Under the optimum experimental conditions, the limit of detection (LOD) and limit of quantitation (LOQ) values were calculated as 0.15 mg/kg and 0.52 mg/kg, respectively. The developed method was checked for its accuracy and applicability by spiking black tea and infant formula samples, and the respective percent recovery results were found to be in the range of 99-102% and 98-103%, respectively.

20.
Environ Monit Assess ; 192(4): 253, 2020 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-32222945

RESUMO

This study describes the development of a sensitive and accurate dispersive liquid-liquid microextraction strategy for the preconcentration and determination of selected pesticides in wastewater and lake water samples by gas chromatography-mass spectrometry. Determination of these pesticides at high accuracy and precision is important because they can be still be found in environmental samples. The type of extraction solvent and type of disperser solvent were optimized using the univariate approach. Furthermore, a Box-Behnken experimental design was used to set up a working model made up of 18 combinations of three variables, tested at three levels. The parameters fitted into the design model were volume of extraction solvent, disperser solvent volume, and mixing period. Analysis of variance was used to evaluate the experimental data to determine the significance of extraction variables and their interactions, before selecting optimum extraction conditions. The method was then applied to aqueous standard solutions between 2.0 and 500 µg L-1, and the limit of detection (LOD) and quantification (LOQ) values obtained for the analytes were between 0.37-2.8 and 1.2-9.4 µg L-1, respectively. The percent recoveries were calculated in the range of 92-114 and 96-110% for wastewater and lake water, respectively. These results validated the accuracy and applicability of the method to the selected matrices.


Assuntos
Monitoramento Ambiental , Microextração em Fase Líquida , Praguicidas/análise , Poluentes Químicos da Água , Clorpirifos , Endossulfano , Cromatografia Gasosa-Espectrometria de Massas , Lagos/química , Fenilcarbamatos , Tiadiazóis/análise , Águas Residuárias/química
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