Search results for "Solvents"
showing 10 items of 291 documents
Application of a low transition temperature mixture for the dispersive liquid–liquid microextraction of illicit drugs from urine samples
2021
© 2021 by the authors.
Selective chromo-fluorogenic detection of DFP (a Sarin and Soman mimic) and DCNP (a Tabun mimic) with a unique probe based on a boron dipyrromethene …
2014
[EN] A novel colorimetric probe (P4) for the selective differential detection of DFP (a Sarin and Soman mimic) and DCNP (a Tabun mimic) was prepared. Probe P4 contains three reactive sites; i.e. (i) a nucleophilic phenol group able to undergo phosphorylation with nerve gases, (ii) a carbonyl group as a reactive site for cyanide; and (iii) a triisopropylsilyl (TIPS) protecting group that is known to react with fluoride. The reaction of P4 with DCNP in acetonitrile resulted in both the phosphorylation of the phenoxy group and the release of cyanide, which was able to react with the carbonyl group of P4 to produce a colour modulation from pink to orange. In contrast, phosphorylation of P4 with…
The complex formation of tetracyclohexylammonium C1-resorcinarene with various guests - an electrospray ionization Fourier transform ion cyclotron re…
2008
The complex formation of a tetraammonium C1-resorcinarene (R+4HCl) was studied using electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Although R+4HCl easily loses its counter ions in the ESI process, a neutral self-assembled structure with an intramolecular circular hydrogen-bonded 16-membered -N(+)-H ... X(-) ... H-N(+)- array with ammonium ion as the charge-giving species was observed in the gas phase. In addition to chloride, several other counter ions were also studied. The size and basicity of the counter ion as well as the size of the charge-giving cation strongly affected the gas-phase stability of the self-assembled system. H/D exchang…
Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route.
2020
Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of …
In-situ suspended aggregate microextraction: A sample preparation approach for the enrichment of organic compounds in aqueous solutions.
2015
Abstract This work presents in-situ suspended aggregate microextraction (iSAME) as a new and expedient sample preparation method. This new concept capitalizes on the general principles of in-situ solvent formation microextraction, in the sense that extraction is carried out in a supramolecular aggregate phase, which is formed in-situ in the sample through one-step process involving ion-association between a cationic surfactant and a benzene sulfonic acid derivative. The suspended aggregate containing the analytes is then collected in the form of a thin-film on the surface of a common filter paper by suction filtration. The entrapped analytes are released by completely dissolving the thin-fi…
Application of integrative cloud point extraction and concentration for the analysis of polyphenols and alkaloids in mulberry leaves
2018
Abstract A simple and efficient method based on cloud point extraction and concentration combined with high performance liquid chromatography was developed for the simultaneous separation and determination of five target compounds (deoxynojirimycin, chlorogenic acid, rutin, isoquercitrin and astragalin) in mulberry leaves samples. Firstly, to obtain a high extraction rate, the ultrasound assisted extraction was developed on acid modified Triton X-114 system. Under the optimal conditions, the total maximum extraction yields of five target compounds reached 20.80 mg/g, which was superior to conventional solvent extraction. After the cloud point extraction and concentration, the HPLC analysis …
DFT calculation of 1J(119Sn,13C) and 2J(119Sn,1H) coupling constants in di- and trimethyltin(IV) compounds
2008
We have tested several computational protocols, at the nonrelativistic DFT level of theory, for the calculation of 1J(119Sn, 13C) and 2J(119Sn, 1H) spin-spin coupling constants in di- and trimethyltin(IV) derivatives with various ligands. Quite a good agreement with experimental data has been found with several hybrid functionals and a double-zeta basis set for a set of molecules comprising tetra-, penta-, and hexa-coordinated tin(IV). Then, some of the protocols have been applied to the calculation of the 2J(119Sn, 1H) of the aquodimethyltin(IV) ion and dimethyltin(IV) complex with D-ribonic acid and to the calculation of 1J(119Sn, 13C) and 2J(119Sn, 1H) of the dimethyltin(IV)-glycylglycin…
Nortriptyline hydrochloride skin absorption: development of a transdermal patch.
2007
The influence of propylen glycol (PG), ethanol, and oleic acid (OA) on nortriptyline hydrochloride (NTH) penetration through human epidermis was studied in vitro at two different pH values (5.5 and 7.4). The influence of lactic acid and polysorbate 80 was studied for a pH of 5.5. Permeation studies through Heat Separated Epidermis, as well as the enhancing effect of the different vehicles, showed a pH dependency. A pH value of 5.5 in the donor solution decreases significantly the permeability coefficient (Kp) with respect to a pH value of 7.4 (0.011+/-0.004 x 10(-6) versus 0.36+/-0.04 x 10(-6)cm/s). The vehicles showed an increasing enhancement effect in the order: polysorbate 80>ethanol/PG…
Determination of bisphenol diglycidyl ether residues in canned foods by pressurized liquid extraction and liquid chromatography–tandem mass spectrome…
2005
Abstract A new confirmatory method for simultaneous determination of bisphenol diglycidyl ether residues (BADGE, BADGE·H2O, BADGE·2H2O, BADGE·H2O·HCl, BADGE·HCl, BADGE·2HCl, BFDGE and BFDGE·2HCl) from canned food has been developed. The proposed method includes extraction by pressurized liquid extraction (PLE) followed by liquid–liquid partition and purification by solid phase extraction (SPE). Several solvent systems and different operating conditions (time, temperature) have been investigated for PLE optimization. A reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to atmospheric pressure chemical ionisation tandem mass spectrometry (APCI-MS–MS) method was developed …
Clean method for the simultaneous determination of propyphenazone and caffeine in pharmaceuticals by flow injection Fourier transform infrared spectr…
1997
A procedure is proposed for the simultaneous FTIR determination of propyphenazone (PFZ) and caffeine (CAF) in pharmaceuticals. The method involves the dissolution of the active principles in CHCl 3 , followed by filtration of sample solutions to remove the excipients. PFZ is then determined by absorbance measurements at 1595 cm - 1 , using a baseline established between 2000 and 890 cm - 1 , and CAF by using the first-derivative values at 1712 cm - 1 , using solutions of PFZ and CAF for external calibration. The method was applied in both the stopped-flow and flow-injection modes, providing precise and accurate results for the analysis of real samples. The incorporation of a distillation un…