نتایج جستجو برای: phase microextraction

تعداد نتایج: 600074  

Journal: :Journal of the science of food and agriculture 2011
Juan José Rodríguez-Bencomo Carolina Muñoz-González Inmaculada Andújar-Ortiz Pedro Jose Martín-Álvarez Maria Victoria Moreno-Arribas Maria Ángeles Pozo-Bayón

BACKGROUND The aim of this study was to evaluate the effect of the whole non-volatile wine matrix composition on the volatility of typical wine aroma compounds by comparing the slopes of regression lines of five deodorised and reconstituted wines with the slopes calculated for the same compounds in a control wine with no matrix effect. RESULTS The main effect observed was a reduction in the s...

Journal: :Biochemical and biophysical research communications 2007
Valia Bravo Samuel Rosero Camillo Ricordi Ricardo L Pastori

Micro RNAs (miRNAs) are small RNA molecules, which function as important regulators of gene expression. We found that RNA preparation methods commonly utilized for miRNA expression studies yield highly unstable miRNAs. We studied the stability of four miRNAs belonging to different miRNAs families. A significant degradation of these molecules may be observed already three days after RNA isolatio...

Journal: :Optics express 2001
J C Martinez-Anton H Canabal J A Quiroga E Bernabeu M A Labajo V C Testillano

We have extended the use of shadow Moiré technique to be implemented in simple curved surfaces by using a flexible grating. Dynamic visual inspection of surface micro-damages is significantly favored by the use of well adapted pliable gratings compared to the use of flat reference gratings. The experimental set-up consists of a plastic foil with a printed Ronchi grating stretched between three ...

Journal: :International journal of occupational safety and ergonomics : JOSE 2008
Hamid-Reza Heidari Seyed Jamaleddin Shahtaheri Farideh Golbabaei Mahmoud Alimohammadi Abbas Rahimi-Froushani

This study describes optimization of headspace solid phase microextraction followed by gas chromatography equipped with a flame ionization detector for toluene at trace level in spiked urine. The parameters affecting the extraction and gas chromatographic determination of analytes were studied: extraction time and temperature; desorption time and temperature; addition of NaCl; and pH, volume an...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور استان تهران - دانشکده شیمی 1392

تلفیق تکنیک های هوشمند دستگاهی با روش های کمومتریکس، امکان آنالیز مخلوط های پیچیده و فرایندهای چند جزئی را فراهم کرده است. با در دست داشتن چنین ابزاری امکان تحلیل داده های اندازه گیری شده فراهم خواهد شد.هدف از انجام این پروژه تجزیه و شناسایی ترکیبات موجود در عرق گیاه آویشن می باشد.ابتدا عرق گیاه آویشن با استفاده از روش میکرواستخراج فاز مایع به دست آمد.در ادامه، کروماتوگرافی gc-ms در ترکیب با رو...

K. Motevalli, M. Zeeb

An efficient dispersive liquid-liquid microextraction using tetraalkylammonium bromide coated silver nanoparticles (DLLME-AgNPs) prepared in chloroform has been successfully applied as electrostatic affinity probes to the microextraction and preconcentration of terazosin prior to spectrofluorimetry analysis. This technique is based on a ternary system of solvents, where appropriate amount of mi...

Journal: :Journal of Chromatography & Separation Techniques 2013

2010
O. Viegas A. Melo O. Pinho

Due to high complexity of most food matrices and the low concentration (ppb levels) of HAs, sensitive and selective analytical methodology is needed. Solid-phase extraction (SPE) is generally used. However it involve tedious and time-consuming and have intrinsic disadvantages like the use of toxic solvents and plugging of the cartridges. These drawbacks can be avoided by using solid-phase micro...

Journal: :Journal of chromatography. A 2004
Mari R Tellez Ikhlas A Khan Brian T Schaneberg Sara L Crockett Agnes M Rimando Mozaina Kobaisy

A new method involving concurrent solid-phase microextraction combined with continuous hydrodistillation of essential oil was developed. This new methodology allowed for the detection by GC-MS of very small amounts of a diagnostic peak for the authentication of Ephedra sinica, in a short period of time and using only small sample sizes. This diagnostic peak was identified as 4-vinylanisole, and...

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