Search results for "ESOL"
showing 10 items of 2444 documents
Optimization of a LC method for the enantioseparation of a non-competitive glutamate receptor antagonist, by experimental design methodology
2006
Abstract The aim of this work was to obtain the direct optical resolution of a new glutamate receptor antagonist (( p -chloro)1-aryl-6,7,-dimethoxy-1,2,3,4-tetrahydroisoquinoline, PS3), by liquid chromatography on Chiralcel ® OD column. A response surface methodology (RSM) was employed to optimize the enantiomeric separation of the racemate with the lowest number of experiments; in particular, a face-centred design (FCD) was applied to evaluate the influence of critical parameters on the experimental response. Furthermore, in order to find the best compromise between several responses, a multicriteria decision-making approach, the Derringer's desirability function, was successful to simulta…
Potential of human serum albumin as chiral selector of basic drugs in affinity electrokinetic chromatography-partial filling technique
2006
The enantiomeric resolution of compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer (BGE), protein, and compound solutions), and plug length. In this paper, the possibility of using HSA as chiral selector for enantioseparation of 28 basic drugs using this methodology is studied. The effect of the physicochemical parameters, the structural properties of compounds, and compound-HSA protein binding percentages over their chiral resolution with HSA is outlined. Based on the results obtained, a decision tree is proposed…
Estuarine sediment quality assessment by Fourier-transform infrared spectroscopy
2010
Partial least squares Fourier-transform infrared (PLS-FTIR) models were developed for the quality assessment of estuarine sediments through the evaluation of several physico-chemical parameters. Models were based on the chemometric treatment of attenuated total reflection (ATR) spectra directly obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 3997 to 523 cm-1, averaging 36 scans per spectrum with a nominal resolution of 8 cm-1. Models were built using reference data obtained for sediment samples collected from Ria de Arousa estuary. Hierarchical cluster classification of sediment ATR spectra was employed for the establishment…
Characterization of the alcoholic fraction of vegetable oils by derivatization with diphenic anhydride followed by high-performance liquid chromatogr…
2008
Abstract Aliphatic and triterpene alcohols present in vegetable oils have been identified and determined by HPLC using UV–vis and MS detection after previous derivatization with diphenic anhydride. The alcoholic fraction was obtained by saponification, extraction and TLC (according to the European Union official procedure). Derivatization was performed in tetrahydrofuran in the presence of suspended grinded urea, which increases the reaction rate and yield. Derivatized extracts were chromatographed on a C8 column using gradient elution with acetonitrile/water mixtures containing 0.1% acetic acid, with UV–vis followed by negative-ion mode MS detection. Using linear discriminant analysis of t…
Trace analysis by ion mobility spectrometry: From conventional to smart sample preconcentration methods. A review.
2018
Ion mobility spectrometry (IMS) is a rapid and high sensitive technique widely used in security and forensic areas. However, a lack of selectivity is usually observed in the analysis of complex samples due to the scarce resolution of the technique. The literature concerning the use of conventional and novel smart materials in the pretreatment and preconcentration of samples previous to IMS determinations has been critically reviewed. The most relevant strategies to enhance selectivity and sensitivity of IMS determinations have been widely discussed, based in the use of smart materials, as immunosorbents, aptamers, molecularly imprinted polymers (MIPs), ionic liquids (ILs) and nanomaterial. …
Comparative modelling study on enantioresolution of structurally unrelated compounds with amylose-based chiral stationary phases in reversed phase li…
2020
[EN] Polysaccharide-based chiral stationary phases (CSPs) are the most used chiral selectors in HPLC. These CSPs can be used in normal, polar organic and aqueous-organic mobile phases. However, normal and polar organic mobile phases are not adequate for chiral separation of polar compounds, for the analysis of aqueous samples and for MS detection. In these situations, reversed phase conditions, without the usual non-volatile additives incompatible with MS detection, are preferable. Moreover, in most of the reported chiral chromatographic methods, retention is too large for routine work. In this paper, the chiral separation of 53 structurally unrelated compounds is studied using three commer…
High-performance liquid chromatographic separation of modified and native melittin following transglutaminase-mediated derivatization with a dansyl f…
1991
Abstract The 26-amino acid linear, amphiphilic peptide melittin was enzymatically modified with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase and a fluorescent derivative of stoichiometry 1:1 was obtained. Reversed-phase and size-exclusion high-performance liquid chromatographic modes were tested in order to resolve the labelled peptide and native species. The influence of several operational variables was analysed and the elution conditions were optimized so that a satisfactory resolution could be achieved in both instances in a rapid, easy manner. Both chromatographic modes offer the possibility of accurate monitoring of the time course of the enzyme-m…
A Simple Software-based Resolver To Digital Conversion System
2022
In this paper, a software-based resolver to digital converter (RDC) is proposed. The hardware signal conditioning circuit is realized using common electronic components, while the algorithm can be implemented either using a microcontroller or an FPGA. Its validation and performance analysis has been carried out using an interior permanent magnet synchronous machine drive and, with comparative purposes, an LTN Servotechnik 1024 ppr incremental encoder. Tests show that the proposed RDC is characterized by a good dynamic response and precision, moreover, due to low computational demand, it can be successfully adopted without significant extra cost.
Criminal Mediation as a Restorative Instrument for Victim: In All Cases and for All Victims?
2012
Insofar as the intention is to provide legal protection, to speak of victims and of certain victims in particular, implies recalling the obscure past that enveloped them with regard to their invisibility in the criminal system as a whole. Society assumed the burden of the criminal response, through the expropriation of the victims’ rights by the State in the interests of that social safeguard. We have for centuries accepted that it was what society required –it was the conquest of civilization, ending “an eye for an eye and a tooth for a tooth” and the lex talionis. That was the best solution, although the outcome of these responses to that situation, owing to frustration, disenchantment an…
Criminal Mediation, an Instrument for Victim Visibility, a Component of Criminal Access to Justice
2018
Insofar as the intention is to provide legal protection, to speak of victims and of certain victims in particular, implies recalling the obscure past that enveloped them with regard to their invisibility in the criminal system as a whole. Society assumed the burden of the criminal response, through the expropriation of the victims’ rights by the State in the interests of that social safeguard. We have for centuries accepted that it was what society required –it was the conquest of civilization, ending “an eye for an eye and a tooth for a tooth” and the lex talionis. That was the best solution, although the outcome of these responses to that situation, owing to frustration, disenchantment an…