Search results for " Analytical"
showing 10 items of 1453 documents
Detection of fluorine using laser-induced breakdown spectroscopy and Raman spectroscopy
2017
In general, the detection of F and other halogens is challenging through conventional techniques. In this paper, various approaches for the qualitative and quantitative analysis of F using the laser-induced breakdown spectroscopy (LIBS) technique were demonstrated. In LIBS, fluorine detection can be realized by means of atomic lines and molecular bands. For the purposes of our experiment, two sets of pellets with various contents of CaF2, CaCO3 and cellulose were analyzed using a lab-based LIBS system under a He atmosphere. The fluorine atomic line at 685.60 nm was correlated with CaF signals proving their close relationship. Consequently, the limits of detection were determined for both an…
Ultraviolet Filters in Cosmetics
2018
Abstract UV filters are used in sunscreen cosmetics to protect skin from the sunlight. Nowadays, they are also incorporated into other daily-use cosmetics. However, many concerns about their safety have been raised, because they can be absorbed through the skin, further metabolized and eventually bioaccumulated and/or excreted. These percutaneous absorption processes may result in various adverse health effects (i.e., allergic contact dermatitis) and other more serious systemic effects, such as carcinogenic and oestrogenic activity. For this reason, UV filters as well as their maximum allowed concentrations have been regulated by the legislations in force. In this sense, analytical control …
Ion mobility mass spectrometry – an efficient tool for the analysis of conformational switch of macrocyclic receptors upon anion binding
2021
Interactions between anions and synthetic macrocyclic receptors belong to the extensively explored area of research due to the particularly important functions of anions in biological and environmental sciences. Structures of anion-macrocycle complexes are closely related to their function, highlighting the importance of structural analysis of the complexes. Here, we discuss the application of ion mobility mass spectrometry (IM-MS) and theoretical calculations to the structural analysis of tetralactam macrocycles (M) with varying flexibility and structural properties, and their complexes with anions [M + X]−. Collision cross section (CCS) values obtained from both direct drift tube (DT) and…
N-Propyl-N′-2-pyridylurea-modified silica as mixed-mode stationary phase with moderate weak anion exchange capacity and pH-dependent surface charge r…
2018
Herein, we present a novel silica-based stationary phase modified with N-propyl-N'-2-pyridylurea selector. Due to the weakly basic properties of the pyridine selector and the presence of residual silanols after selector immobilization, a zwitterionic surface with a pI observed at approximately pH 5.5 was measured by electrophoretic light scattering in pH-dependent ζ-potential determinations. The capability of the new N-propyl-N'-2-pyridylurea-modified silica to serve as mixed-mode stationary phase was investigated. For this purpose, it was characterized under RP and HILIC conditions using test mixtures. Subsequent classification of this stationary phase in comparison to in-house and commerc…
Stable-bond polymeric reversed-phase/weak anion-exchange mixed-mode stationary phases obtained by simultaneous functionalization and crosslinking of …
2019
Abstract A polymeric reversed-phase/weak anion exchange (Poly-RP/WAX) mixed-mode stationary phase has been prepared by coating of a poly(3-mercaptopropyl)methylsiloxane film on vinyl-modified silica (100 A, 5 μm) and simultaneous in situ functionalization with N-(10-undecenoyl)-3-aminoquinuclidine as well as crosslinking to the vinyl silica surface by solventless thiol-ene double click reaction. Such bonding chemistry showed greatly enhanced stability compared to brush-type analogs with bifunctional siloxane bonding to silica. Solid-state 29Si-CP/MAS NMR confirmed the immobilization of the siloxane layer. pH-Dependent ζ-potential determinations revealed a high anion-exchange capacity over t…
Surface-anchored counterions on weak chiral anion-exchangers accelerate separations and improve their compatibility for mass-spectrometry-hyphenation
2017
In the present work we propose new variants of chiral stationary phases (CSP) with tert-butylcarbamoylquinine (tBuCQN) as chiral selector molecule. Four tBuCQN-CSPs with distinct bonding chemistries are compared in terms of their pH-dependent surface charge by ζ-potential determinations, by achiral and chiral liquid chromatographic tests and LC-ESI-MS hyphenation. In one embodiment tBuCQN was immobilized on 3-mercaptopropylmethylsilyl-modified silica by thiol-ene click reaction (brush type CSP with selector coverage of 0.38mmol/g). In another embodiment, poly-(3-mercaptopropyl)-methylsiloxane was coated onto vinylized silica particles in presence of tBuCQN and radical initiator. The tBuCQN …
Attachment of chloride anion to sugars: mechanistic investigation and discovery of a new dopant for efficient sugar ionization/detection in mass spec…
2012
International audience; A new method for efficient ionization of sugars in the negative-ion mode of electrospray mass spectrometry is presented. Instead of using strongly hydrophobic dopants such as dichloromethane or chloroform, efficient ionization of sugars has been achieved by using aqueous HCl solution for the first time. This methodology makes it possible to use hydrophilic dopants, which are more appropriate for chromatographic separation techniques with efficient sugar ionization and detection in mass spectrometry. The interaction between chloride anions and monosaccharides (glucose and galactose) was studied by DFT in the gas phase and by implementing the polarizable continuum mode…
Comparative study of protective coatings for the conservation of Urban Art
2020
Abstract Contemporary mural paintings are complex artworks for several reasons, including the heterogeneity of the materials used to make them, and the different types of substrate on which the painting layers can be applied. Currently we are focused on a technical-scientific research aimed to solve the issues related to the long-term care and maintenance of murals, by evaluating the performance of several protective coatings applied on these artworks. This paper deals with a preliminary experimentation aimed to: (a) study the interaction of antigraffiti products on common synthetic paints; (b) test the effectiveness and efficiency of several commercial products used as antigraffiti; (c) de…
Cold plasma processing of powdered Spirulina algae for spore inactivation and preservation of bioactive compounds
2020
Abstract Technologies for controlling microbial risks in a heat and humidity sensitive food powder are still limited. To preserve bioactive compounds while inactivating Bacillus subtilis spores in powdered Spirulina microalgae (Arthrospira platensis) with a non-thermal atmospheric plasma is the challenge presented in this paper. Artificially contaminated powder was treated with a custom-made surface micro-discharge cold atmospheric pressure plasma (SMD-CAPP) at the effective, specific surface energy of the plasma (Es) of 7–15 mW/cm2. The inactivation of spores in air plasma was faster than in nitrogen plasma. The final effect after 5 min exposure time of close to 2 log10 reduction could be …
Phenolic profile of oils obtained from “horchata” by-products assisted by supercritical-CO2 and its relationship with antioxidant and lipid oxidation…
2019
Abstract In this study, the effect of different supercritical CO 2 (SC-CO 2 ) pressures (10–40 MPa) on phenolic compounds extraction in oils obtained from “ horchata ” by-products was evaluated, and the results were compared to those obtained after conventional oil extraction (CE). Moreover, the relationship between the individual phenolic compounds and the total antioxidant capacity as well as oil oxidative quality parameters was compared. The phenolic profile and contents were largely influenced by extracting conditions. The main phenolic compound obtained by SC-CO 2 was the isohydroxymatairesinol, particularly at 30 and 40 MPa, while 3-vinylphenol was the predominant compound in oils ext…