Search results for " Spectroscopy"
showing 10 items of 6851 documents
New Alternative in the Methodology of Extraction and Dyeing with Active Molecules Derived from Vegetal Sources
2016
Abstract The general objective of this study refers to the identification of a sustainable and physical methodology of extraction of active compounds, envisaging the preservation of the high purity active natural dye molecule from nut shell (juglone), even under the conditions of an extraction performed in a mixt solvent medium (water-ethanol). The second major objective of the study consists of the application of these above mentioned dyes onto natural and synthetic substrates, thus making a correlation between their colour attributes and the fibrous composition of the substrates they are applied on. The motivation of this research was given by the identification of an improved extraction …
Photochemical derivatization and fluorimetric determination of reserpine in a flow-injection assembly
1991
Abstract The fluorimetric flow-injection determination of reserpine was achieved with the drug being derivatized on-line by photoreaction. PTFE tubing was helically coiled around a germicide lamp located between the injection valve and detector. Two analytical procedures are proposed using either dilute acetic acid or pure methanol as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of reserpine in pharmaceutical formulations.
Fast authentication of tea tree oil through spectroscopy
2018
Two new procedures, based on infrared spectroscopy in the near infrared (NIR) and mid infrared (MIR), have been developed for the authentication of tea tree oil (TTO) commercial samples. Infrared measurements were made on untreated samples by transmission NIR and attenuated total reflectance (ATR) followed by partial least square discriminant analysis (PLS-DA). These methods offer a fast and low cost alternative to enantiomeric two-dimensional gas chromatography coupled to mass detection usually employed to discriminate between authentic and non-authentic samples. In these studies, a set of 267 samples, including authentic and non-authentic labelled tea tree oil samples, were used to build …
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…
Simultaneous determination of acetylsalicylic acid and caffeine in pharmaceuticals by flow injection with fourier transform infrared detection.
1993
Abstract A fast quality control methodology has been developed for the simultaneous determination of acetylsalicylic acid (ASA) and caffeine in pharmaceuticals by flow injection—Fourier Transform Infrared Spectrometry. The method is based on the solubilization of ASA and caffeine in CH2Cl2 and the use of a flow system to introduce samples and standards in the spectrometer. Two solutions, containing 90 and 110% of the reported concentration of the two active principles in the sample, were employed in order to control the extreme tolerance levels accepted by the International Pharmacopeia for the composition of formulations. A 300 μl volume of each solution was injected in turn, into a carrie…
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…
Determination of α-Tocopherol in Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Stability of α-Tocopherol under Dif…
2011
In order to study the clinical effects of the antioxidant alpha-tocopherol (tocofersolan, CAS 30999-06-5) a simple, robust, sensitive and reliable high performance liquid chromatography (HPLC) method using fluorescence detection for the daily measurement of alpha-tocopherol concentration in plasma is described. Several methods of HPLC analysis using fluorescence techniques are published, however, investigations of the stability of alpha-tocopherol during sample preparation under different conditions are relevant in the routine measurements and have to date not been reported. Therefore a modified method, both sensitive and robust, qualified for the day-by-day measurement of alpha-tocopherol …
Liquid chromatography-Fourier transform infrared spectrometric determination of cholesterol in animal greases
1997
Abstract Stearic acid, cholesterol and cholesteryl palmitate have been separated in less than 14 min by liquid chromatography on a column (3.9 mm i.d.×150 mm) of Nova-Pack C 18 (5 μm) using chloroform–acetonitrile (45 : 55) as mobile phase pumped at 0.5 ml min −1 ; Fourier transform infrared (FTIR) spectrometry was employed for both, general detection at 2868 or 2855 cm −1 and selective detection at 3285 cm −1 for stearic acid and 3526 cm −1 for cholesterol. In all cases a baseline established at 3900 cm −1 , 9-point smoothing and chromatographic peak height measurements were used. The method has been validated by application to the determination of cholesterol in animal greases and fish oi…
Synthesis and characterization of alumina R chemically modified withn-octyl for use as a stationary phase in TLC
2003
A stationary phase for thin-layer chromatography has been prepared by attaching 1-octene to alumina R. This stationary phase has been characterized by elemental analysis, measurement of specific surface area, IR spectroscopy, and by chromatographic testing.