0000000000280060
AUTHOR
Yasmina Daghbouche
Flow Injection Fourier Transform Infrared Determination of Caffeine in Soft Drinks
A fully automated procedure has been developed for FT-IR determination of caffeine in soft drinks. Samples are first degasified by filtration and then directly injected into a flow manifold and passed through a 100 mg C18 SPE cartridge, conditioned with methanol and water. After the cartridge has been cleaned with water, the caffeine is eluted with CHCl3 and stabilized with ethanol. The flow injection (FI) recording is obtained by measuring the absorbance at 1658 cm-1 with a baseline established at 1800 cm-1. Area values for the FI recording obtained between 0.4 and 1.4 min after sample injection are interpolated in the calibration graph of a series of aqueous standards of caffeine, which w…
Quantification of phenolic acids by partial least squares Fourier-transform infrared (PLS-FTIR) in extracts of medicinal plants.
Introduction Phenolic compounds are ubiquitous compounds found in all plants as their secondary metabolites. Phenols are becoming increasingly important particularly because of their beneficial effects on health. Objective To provide a faithful calibration model for the simultaneous determination and quantification of phenolic acids, as salicylic, vanillic, p-hydroxybenzoic acids, eugenol and thymol in different extracts of medicinal plants, a comparative study was made between two methods of infrared measurements based on attenuated total reflectance (ATR) and transmission. Methods Characteristic absorbance peak heights of mid-infrared spectra of individual phenolic acids were measured for…
Eucalyptol-based green extraction of brown alga Zonaria tournefortii
Abstract A green extraction method, based on the use of 1,8-cineole (eucalyptol) as biosolvent, has been developed to prepare crude extracts from the brown alga Zonaria tournefortii characterized by chemical composition, particularly dominated by phenolic compounds derived from phloroglucinol. The main advantage of the developed technique are the recovery of eucalyptol, based on multistep liquid-liquid extraction with distilled water, followed by centrifugation and elimination of the aqueous phase, and the complete recycling of biosolvent by steam distillation. A comparative study between the proposed green extract and the conventional extract, prepared by solvent maceration using the mixtu…
Essential oil counterfeit identification through middle infrared spectroscopy
Abstract Infrared spectroscopy (FTIR) has been employed for a fast quality control of commercial essential oils from different plant species. 47 samples were obtained from Algerian and Spanish market and directly measured, without any previous treatment, by attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR), in the wavenumber region between 4000 and 550 cm−1. Pure essential oils were obtained by hydro- and steam-distillation extraction methods and their ATR spectra obtained. Results found evidenced the presence of solvents in some commercial formulations and permitted a rapid authentication of pure essential oils correctly extracted from those diluted. The propo…
Liquid chromatography-Fourier transform infrared spectrometric determination of cholesterol in animal greases
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…
Fourier transform infrared analysis of commercial formulations for Varroa treatment
A comparative study has been carried out between univariate and multivariate calibration strategies for the simultaneous determination of camphor, thymol, menthol and eucalyptol in commercial formulations used for Varroa treatment. Absorbance peak heights of the transmission mid-infrared (MIR) spectra of individual monoterpenes, prepared in dichloromethane, were measured at 1737, 1151, 1022 and 980 cm−1 (corrected with a base-line at 1933 cm−1) for camphor, thymol, menthol and eucalyptol, respectively. Data were processed using the proportional equations approach in univariate mode. For multivariate calibration, partial least squares (PLS) regression based on a classical 42 design for stand…
Evaluation of extraction alternatives for Fourier transform infrared spectrometric determination of oil and greases in water
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…