Search results for "Fourier transform"
showing 10 items of 1138 documents
Miniature diamond-anvil cells for FTIR-microspectroscopy of small quantities of biosamples.
2018
Fourier transform infrared (FTIR) spectroscopy techniques and data analyses have become widely available, are easy to use, and are convenient for studies of various biosamples, especially in biomedical science. Yet, cultivation of cells and purification of cell components are costly, often methodically challenging, and time and labor consuming. Therefore, reduction of the sample amount is of high value. Here we propose a novel method for the analysis of small quantities of biosamples by FTIR-microscopy of dry films using a diamond-anvil cell (DAC). This approach allows us to decrease the sample volume at least a hundred times compared to that for a high-throughput screening device (HTS-XT, …
Essential oil counterfeit identification through middle infrared spectroscopy
2018
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…
Infrared biospectroscopy for a fast qualitative evaluation of sample preparation in metabolomics.
2014
Liquid chromatography-mass spectrometry (LC-MS) has been increasingly used in biomedicine to study the dynamic metabolomic responses of biological systems under different physiological or pathological conditions. To obtain an integrated snapshot of the system, metabolomic methods in biomedicine typically analyze biofluids (e.g. plasma) that require clean-up before being injected into LC-MS systems. However, high resolution LC-MS is costly in terms of resources required for sample and data analysis and care must be taken to prevent chemical (e.g. ion suppression) or statistical artifacts. Because of that, the effect of sample preparation on the metabolomic profile during metabolomic method d…
Sweeteners determination in table top formulations using FT-Raman spectrometry and chemometric analysis
2004
Abstract A partial least squares (PLS) Fourier transform Raman spectrometry procedure based on the measurement of solid samples contained inside standard glass vials, has been developed for direct and reagent-free determination of sodium saccharin and sodium cyclamate in table top sweeteners. A classical 22 design for standards was used for calibration, but this system provides accuracy errors higher than 13% w/w for the analysis of samples containing glucose monohydrate. So, an extended model incorporating glucose monohydrate (23 standards) was assayed for the determination of sodium saccharin and sodium cyclamate in all the samples. Mean centering spectra data pre-treatment has been emplo…
Stopped-flow Fourier-transform infra-red spectrometric speciation of glycolic and lactic acids in cosmetic formulations
2001
The dermatological activity of cosmetic formulations containing alpha-hydroxyacids depends on their different chemical forms, and it is therefore useful to determine these species in the finished products. In the present report a new procedure for studying the protonation equilibria of glycolic and lactic acids by stopped-flow Fourier-transform infra-red (FTIR) spectrometry is described. The procedure was validated for use in the speciation of glycolic and lactic acids in cosmetic formulations, with preferential attention given to glycolic acid, which is the most widely used. Species of these alpha-hydroxyacids can be approximately determined at different pHs and the total content of each a…
Determination of lecithin and soybean oil in dietary supplements using partial least squares-Fourier transform infrared spectroscopy.
2008
Lecithin and soybean oil in dietary supplements were determined by Fourier transform infrared spectrometry transmission measurements in dichloromethane in combination with a partial least squares (PLS) regression. Two different PLS models were developed, using 16 synthetic mixtures of analytes in dichloromethane, making measurements in the spectral range from 931.8 to 1252.3 cm(-1) for lecithin and from 911.4 to 1246.9 cm(-1) and 1695.3 to 1774.5 cm(-1) for soybean oil. Seven products from the Spanish market with lecithin concentrations between 21.1% and 99.1% and soybean oil concentrations between 0% and 37.2% were analyzed by the proposed method and the data was compared to a chromatograp…
The chemistry of Cr(VI) adsorption on to poly(p-phenylenediamine) adsorbent
2019
Abstract Water pollution due to industrial processes has necessitated and spurred robust research into the development of adsorbent materials for remediation. Polyphenylenediamines (PPD) have attracted significant attention because of their dual cationic and redox properties. They are able to reduce Cr(VI) to Cr(III) in solution. Interrogation of the chemical processes involved in the Cr(VI) adsorption on para-PPD was primarily by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. It was confirmed that the underlying oxidation of the amino groups to imines during the reduction of Cr(VI) to Cr(III) was irreversible. This process occurred at both acidi…
Premature aging in bone of fish from a highly polluted marine area
2015
Fish species have attracted considerable interest in studies assessing biological responses to environmental contaminants. In this study, the attention has been focussed on fishbone of selected fish species from a highly polluted marine area, Augusta Bay (Italy, Central Mediterranean) to evaluate if toxicant elements had an effect on the mineralogical structure of bones, although macroscopic deformations were not evident. In particular, an attempt was made to evaluate if bone mineral features, such as crystallinity, mineral maturity and carbonate/phosphate mineral content, determined by XR-Diffraction and FT-IR Spectroscopy, suffered negative effects due to trace element levels in fishbone,…
Glucagon fibril polymorphism reflects differences in protofilament backbone structure
2010
Amyloid fibrils formed by the 29-residue peptide hormone glucagon at different concentrations have strikingly different morphologies when observed by transmission electron microscopy. Fibrils formed at low concentration (0.25 mg/mL) consist of two or more protofilaments with a regular twist, while fibrils at high concentration (8 mg/mL) consist of two straight protofilaments. Here, we explore the structural differences underlying glucagon polymorphism using proteolytic degradation, linear and circular dichroism, Fourier transform infrared spectroscopy (FTIR), and X-ray fiber diffraction. Morphological differences are perpetuated at all structural levels, indicating that the two fibril class…
Cytotoxic hydrophilic iminophosphorane coordination compounds of d8 metals. Studies of their interactions with DNA and HSA
2012
The synthesis and characterization of a new water-soluble N,N-chelating iminophosphorane ligand TPAN-C(O)-2-NC(5)H(4) (N,N-IM) (1) and its d(8) (Au(III), Pd(II) and Pt(II)) coordination complexes are reported. The structures of cationic [AuCl(2)(N,N-IM)]ClO(4) (2) and neutral [MCl(2)(N,N-IM)] M=Pd (3), Pt(4) complexes were determined by X-ray diffraction studies or by means of density-functional calculations. While the Pd and Pt compounds are stable in mixtures of DMSO/H(2)O over 4 days, the gold derivative (2) decomposes quickly to TPAO and previously reported neutral gold(III) compound [AuCl(2)(N,N-H)] 5 (containing the chelating N,N-fragment HN-C(O)-2-NC(5)H(4)). The cytotoxicities of co…