Loading...
Search for:
liquid-phase-microextraction
0.009 seconds
A New Approach Towards Modified Single Drop Microextraction Using Solvents with Densities Higher than Water
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
In the present work, the combination of single drop liquid phase microextraction and gas chromatography-mass detector (GC-MS) was used for determination of pesticides, Clodinafop, Haloxyfop and Fenoxyprop in natural water samples. a novel techniques based on SDME for develop in which solvents with higher density than water was successfully used. this technique could overcome some limitations of conventional SDME such as instability of organic droplet and limited stirrer rate in which result increasing the mass transfer rate and extraction efficiency. Experimental liquid phase microextraction (LPME) conditions, such as extracting solvent, stirring rate, micro drop volume, extraction time, pH...
Development of Liquid-Phase Microextraction Technique Combined with Gas Chromatography and Chemometric Techniques for Extraction and Determination of Some Pesticides in Saffron
, M.Sc. Thesis Sharif University of Technology ; Parastar Shahri, Hadi (Supervisor)
Abstract
Today, with increasing concerns about the health of food and its effects on human health, ensuring the quality of food has become a big challenge for regulatory institutions. This issue is more important in the case of foods that have high nutritional and economic value. Among different food items, saffron is especially important due to its low production rate and high economic value. In this research, a new approach based on the diffusion liquid-liquid microextraction method (DLLME) along with gas chromatography-flame ionization detector (GC-FID) combined with chemometrics techniques has been developed to measure the amount of two pesticides in saffron. In this regard, in the extraction...
Determination of essential oil components of artemisia haussknechtii boiss. using simultaneous hydrodistillation-static headspace liquid phase microextraction-gas chromatography mass spectrometry
, Article Journal of Chromatography A ; Volume 1160, Issue 1-2 , 2007 , Pages 81-89 ; 00219673 (ISSN) ; Sereshti, H ; Sharif University of Technology
2007
Abstract
A novel method for extraction and analysis of volatile compounds of Artemisia haussknechtii Boiss., using simultaneous hydro-distillation and static headspace liquid microextraction followed by gas chromatography-mass spectrometry (SHD-SHLPME-GCMS) is developed. SHLPME parameters including nature of extracting solvent, headspace volume and design, extraction time, sample weight and microdrop volume were optimized. Comparison of hydro-distillation gas chromatography-mass spectrometry and HD-SHLPME-GCMS showed that the latter method is fast, simple, inexpensive and effective for the analysis of volatile compounds of aromatic plants. By using this method, 56 compounds were extracted and...
Headspace solvent microextraction as a simple and highly sensitive sample pretreatment technique for ultra trace determination of geosmin in aquatic media
, Article Journal of Separation Science ; Volume 29, Issue 1 , 2006 , Pages 57-65 ; 16159306 (ISSN) ; Salemi, A ; Sharif University of Technology
2006
Abstract
A headspace solvent microextraction method was developed for the trace determination of geosmin, an odorant compound, in water samples. After performing the extraction by a microdrop of an organic solvent, the microdrop was introduced directly into a GC-MS injection port. One-at-the-time optimization strategy was applied to investigate and optimize some important extraction parameters such as type of solvent, drop volume, temperature, stirring rate, ionic strength, sample volume, and extraction time. The analytical data exhibited an RSD of less than 5% (n = 5), a linear calibration range of 5-900 ng/L (r2 > 0.998), and a detection limit of 0.8 and 3.3 ng/L using two different sets of...
Immersed solvent microextraction and gas chromatography-mass spectrometric detection of s-triazine herbicides in aquatic media
, Article Analytica Chimica Acta ; Volume 537, Issue 1-2 , 2005 , Pages 81-87 ; 00032670 (ISSN) ; Khalilian, F ; Sharif University of Technology
Elsevier
2005
Abstract
An immersed solvent microextraction (SME) method was successfully developed for the trace enrichment of s-triazine herbicides from aquatic media. A microdrop of butyl acetate was applied as the extraction solvent. After extraction, the microdrop was introduced directly into a gas chromatography-mass spectrometry (GC-MS) injection port. Some important extraction parameters such as type of solvent, extraction time, stirring rate, and temperature were investigated and optimized. The highest possible microdrop volume of 3 μl, a sampling temperature of 60°C, and use of butyl acetate are major parameters to obtain high enrichment factors. The enrichment factor and linearity was studied by...
Towards greater mechanical, thermal and chemical stability in solid-phase microextraction
, Article TrAC - Trends in Analytical Chemistry ; Volume 34 , 2012 , Pages 126-138 ; 01659936 (ISSN) ; Piri-Moghadam, H ; Naderi, M ; Sharif University of Technology
Abstract
Solid-phase microextraction (SPME) is a fast, solvent-free technique, which, since its introduction in the 1990s, has been increasingly applied to sample preparation in analytical chemistry. Conventional SPME fibers are fabricated by making a physical bond between the usual silica substrate and the polymeric coatings. However, some applications are limited, as the lifetime and the stability of conventional SPME fibers cannot meet the demands of analyzing relatively non-volatile compounds with more polar moieties. There have been attempts to analyze less volatile compounds by increasing the thermal, physical and chemical stability of the fibers. In this review, we present some new...
Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry
, Article Journal of Chromatography A ; Volume 1413 , September , 2015 , Pages 117-126 ; 00219673 (ISSN) ; Sereshti, H ; Parastar, H ; Sharif University of Technology
Elsevier
2015
Abstract
In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9 μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a...
An imprinted interpenetrating polymer network for microextraction in packed syringe of carbamazepine
, Article Journal of Chromatography A ; Volume 1491 , 2017 , Pages 1-8 ; 00219673 (ISSN) ; Bagheri, H ; Es haghi, A ; Amini Tabrizi, R ; Sharif University of Technology
Abstract
An imprinted interpenetrating polymer network (IPN) was synthesized and used as a medium for isolation of carbamazepine from urine samples. The polymer network consisted of a homogeneous polystyrene–sol gel hybrid constructed by in–situ radical polymerization method. In this process, within the sol–gel reaction duration, styrene monomer could penetrate into the reaction mixture and after the polymerization initiation, a monolithic IPN structure was prepared. The scanning electron microscopy (SEM) image and energy dispersive spectroscopy (EDX) are indications of the polystyrene dispersion at nano- to micro-meter level in the sol gel matrix. Eventually, the synthesized IPN was used as a...
Implementing a superhydrophobic substrate in immersed solvent–supported microextraction as a novel strategy for determination of organic pollutants in water samples
, Article Ecotoxicology and Environmental Safety ; Volume 163 , 2018 , Pages 104-110 ; 01476513 (ISSN) ; Asem Yousefi, A ; Bagheri, H ; Sharif University of Technology
Academic Press
2018
Abstract
In this research, a new approach for extraction and determination of polycyclic aromatic hydrocarbons from sea and rain water samples was developed by implementing a superhydrophobic substrate and consuming the least amount of solvent. This version of solvent–supported microextraction enabled us to perform the procedure in the immersion mode with the slightest troubles arising from water leakage into the gas chromatography. The superhydrophobic property leads to the fixation of extracting solvent on the substrate surface during water sampling. To prepare a superhydrophobic substrate, a piece of melamine foam was coated by tannic acid and silica nanoparticles using methyltrimethoxysilane and...
Development of multi-response optimization and quadratic calibration curve for determination of ten pesticides in complex sample matrices using QuEChERS dispersive liquid–liquid microextraction followed by gas chromatography
, Article Journal of Separation Science ; Volume 42, Issue 23 , 2019 , Pages 3553-3562 ; 16159306 (ISSN) ; Parastar, H ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
In this study, QuEChERS combined with dispersive liquid-liquid microextraction is developed for extraction of ten pesticides in complex sample matrices of water and milk. In this regard, effective factors of proposed extraction technique combined with gas chromatography with flame ionization detector were designed, modeled, and optimized using central composite design, multiple linear regression, and Nelder–Mead simplex optimization. Later, univariate calibration model for ten pesticides was developed in concentration range of 0.5–100 ng/mL. Surprisingly, quadratic calibration behavior was observed for some of the pesticides. In this regard, Mandel's test was used for evaluating linearity...
Polyamide/titania hollow nanofibers prepared by core–shell electrospinning as a microextractive phase in a fabricated sandwiched format microfluidic device
, Article Journal of Chromatography A ; Volume 1528 , 2017 , Pages 1-9 ; 00219673 (ISSN) ; Hashemi Hedeshi, M ; Bagheri, H ; Sharif University of Technology
Abstract
In this study, a low–cost microfluidic device from polymethyl methacrylate was fabricated by laser engraving technique. The device is consisted of a central chip unit with an aligned microchannel. Both sides of the engraved microchannel were sandwiched by two synthesized sheets from polyamide/titania (PA/TiO2) hollow nanofibers as extractive phases. The inlet and outlet of the device were connected to the polyether ether ketone tubes, while a peristaltic pump was used to deliver both sample and desorbing solvent through the microchannel. The recorded scanning electron microscopy images from the surface of the synthesized PA/TiO2 nanofibers, exhibit a good degree of homogeneity and porosity...
Immersed single-drop microextraction-electrothermal vaporization atomic absorption spectroscopy for the trace determination of mercury in water samples
, Article Journal of Hazardous Materials ; Volume 165, Issue 1-3 , 2009 , Pages 353-358 ; 03043894 (ISSN) ; Naderi, M ; Sharif University of Technology
2009