Search results for "Fourier Transform Infrared"
showing 10 items of 598 documents
Ab initio calculations and vibrational spectroscopy on the phenylenediamine isomers
1998
Molecular orbital calculations at HF and MP2 levels have been performed using the 6-3IG** basis set for full geometry optimization of the phenylenediamine isomers. Our results show that only a transoid conformer is found for o-phenylenediamine, whereas cis and trans conformers exist for m- and p-phenylenediamine. Vibrational normal modes have been also analyzed for the gas phase and in chloroform solution, and compared with experimental data we have obtained using FTIR spectroscopy. © 1998 Elsevier Science B.V.
Biogenic synthesis of palladium nanoparticles using Pulicaria glutinosa extract and their catalytic activity towards the Suzuki coupling reaction.
2014
Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report a facile and eco-friendly method for the synthesis of palladium (Pd) nanoparticles (NPs) using an aqueous solution of Pulicaria glutinosa, a plant widely found in a large region of Saudi Arabia, as a bioreductant. The as-prepared Pd NPs were characterized using ultraviolet-visible (UV-vis) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). The hydroxyl groups of the plant extract (PE) molecules were found mainly responsible for the red…
Gas chromatography-fourier transform infrared spectrometry of fatty acids: New Applications with a direct deposition interface
1998
Infrared spectroscopy is a suitable spectroscopic method to differentiate geometric Z and E isomers of unsaturated compounds. A direct-deposition Fourier transform infrared spectrometer (FTIR), coupled to a gas chromatograph, was used successfully to analyze with a high sensitivity traces of C18:1 fatty acid methyl ester (FAME) isomers. It could also conclusively distinguish between isomers of conjugated diunsaturated FAME. The achievable sensitivity of this direct-deposition device makes possible accurate FAME mixture analyses that are not currently attainable with the more conventional light-pipe interface.
Application of point-to-point matching algorithms for background correction in on-line liquid chromatography–Fourier transform infrared spectrometry …
2009
A new background correction method for the on-line coupling of gradient liquid chromatography and Fourier transform infrared spectrometry has been developed. It is based on the use of a point-to-point matching algorithm that compares the absorption spectra of the sample data set with those of a previously recorded reference data set in order to select an appropriate reference spectrum. The spectral range used for the point-to-point comparison is selected with minimal user-interaction, thus facilitating considerably the application of the whole method. The background correction method has been successfully tested on a chromatographic separation of four nitrophenols running acetonitrile (0.08…
Partial least squares attenuated total reflectance IR spectroscopy versus chromatography: the greener method
2012
Method election is a complex task that must be done carefully in order to ensure the capability of analytical methodologies to provide appropriate data for problem solving. This is a real challenge in all fields, but especially with bioanalysis, which in many cases involves the need to do a large number of determinations in complex
Determination of critical eluent composition for polyethylenglycols using on-line liquid chromatography-Fourier transform infrared spectrometry.
2008
In this work, it has been extended to methanol:water mobile phases, the use of a background correction method for on-line LC-FTIR measurements named Univariate background correction based on the use of a reference spectra matrix (UBC-RSM) and absorbance ratios. It permits to overcome the problem related to spectral changes occurring during the gradient elution, which in the past limited the on-line coupling of LC and FTIR to isocratic elutions. The combined use of the aforementioned background correction technique in on-line isocratic and gradient LC-FTIR, and partial least squares (PLS) has been applied for the search of the critical conditions for polymers. Polyethylenglycol (PEG) has bee…
Univariate method for background correction in liquid chromatography–Fourier transform infrared spectrometry
2007
An univariate method is proposed for background correction in on-line gradient liquid chromatography-Fourier transform infrared (LC-FTIR) spectrometry using acetonitrile:water as mobile phase components. The method is based on the calculation of the ratio of absorbances (AR) at two characteristic wavenumbers for each spectrum. This parameter is subsequently used to locate the most appropriated eluent spectrum within a reference spectra matrix (RSM) to be subtracted from each spectrum included in the sample chromatogram. To correct minor changes in eluent spectra intensity during the elution of analytes, a correction factor (Kf), defined as the ratio of the absorbance of the sample and the s…
Seafood freshness determination through vapour phase Fourier transform infrared spectroscopy.
2006
Abstract A new vapour-phase manifold has been developed to determine trimethylamine (TMA) in fish and cephalopod samples by Fourier transform infrared (FT-IR) spectroscopy. Samples were treated off-line for 1 h with trichloroacetic acid (TCA), filtered and washed. The obtained extracts were aspirated and alkalinized with NaOH 2.0 M, in an on-line system. TMA was separated from the solution in a gas phase separator and then transported by means of a nitrogen carrier into a home made 10 cm pathlength IR gas cell, where the corresponding FT-IR spectra were acquired by accumulating 30 scans per spectrum with 2 cm−1 nominal resolution. The method was applied to the determination of TMA in natura…
Evaluation of extraction alternatives for Fourier transform infrared spectrometric determination of oil and greases in water
1997
Abstract Liquid-liquid extraction (LLE), solid phase extraction (SPE) and microwave-assisted extraction are evaluated for Fourier transform infrared (FTIR) spectrometric determination of oil and grease in polluted waters. A fast microwave-assisted quantitative procedure is proposed for the total extraction of oil and grease into CCl 4 from water samples, with an irradiation time of 1 min at an exit power of 520 W using closed PTFE vessels. The FTIR quantification of oil and grease is carried out by the measurement of the area under the absorbance spectra in the range between 3058 and 2780 cm −1 , with a baseline established between 3200 and 2700 cm −1 . The analytical features of the propos…
Thermally Induced Isomerisation Kinetics of the 9c11t and 10t12c Conjugated Linoleic Acids in Triacylglycerols as Studied by FT-IR Spectrometry Aided…
2014
Published version of an article from the journal:The Open Spectroscopy Journa. Also available from the publisher:http://dx.doi.org/10.2174/1874383801004010041. Open Access Isomerisation kinetics of the 9c11t and 10t12c Conjugated Linoleic Acids (CLA) in triaclglycerols at isothermal conditions (250, 280 and 325oC) has been studied by infrared spectroscopy. Fifteen micro liter portions of the glycerides were placed in micro glass ampoules and sealed under nitrogen. Several glass tubes containing the same triacylglycerols were then subjected to thermal treatment. The glass tubes were removed at regular time intervals, cut open, and a part of the contents in each glass tube analysed by infrare…