Search results for "Indicator"

Application of solid-phase microextraction combined with derivatization to the enantiomeric determination of amphetamines.

2005

Abstract The utility of combining chiral derivatization and solid-phase microextraction (SPME) for the enantiomeric analysis of primary amphetamines by liquid chromatography has been investigated. Different derivatization/extraction strategies have been evaluated and compared using the chiral reagent o -phthaldialdehyde (OPA)– N -acetyl- l -cysteine (NAC) and fibres with a Carbowax-templated resin coating. Amphetamine, norephedrine and 3,4-methylenedioxyamphetamine (MDA) were used as model compounds. On the basis of the results obtained, a new method is presented based on the derivatization of the analytes in solution followed by SPME of the OPA–NAC derivatives formed. The proposed conditio…

A tailor-made nucleoside-based colourimetric probe of formic acid

2014

A ratiometric, specific probe of formic acid has been developed. It is based on intermolecular nucleobase-pairing of inosine-capped plasmonic nanoparticles to form nucleoside channels, which are destabilised by the analyte.

Prediction of the chemiluminescent behavior of pharmaceuticals and pesticides.

2001

The present paper deals with the first attempt to apply molecular connectivity calculations to predict a chemical property with analytical usefulness: the chemiluminescent behavior of substances when reacted with common oxidants in a liquid phase. Preliminary evidence when searching for new direct CL methods consisted of the examination of analyte reaction with a wide range of oxidants and media. This task, which results in time-consuming and trial-and-error expensive procedures, is necessary due to ensure empirical or theoretical rules for CL prediction are available. On the other hand, in quantitative structure-activity relationship studies, molecular connectivity is a topological method …

Optimization of selenium determination in human milk and whole blood by flow injection hydride atomic absorption spectrometry.

1998

abstract A flow injection hydride atomic absorption spectrometry (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HN03 and 0.25 mL H202 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140 C (2-3 h). Se (VI) was reduced to Se (IV) with hydrochloric acid. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of argon carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/m…

Beads of Acryloylated Polyaminoacidic Matrices Containing 5-Fluorouracil for Drug Delivery

2002

Spherical polymeric microparticles have been prepared by a reverse phase suspension polymerization technique. The starting polymer was alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), partially derivatized with glycidylmethacrylate (GMA). PHEA-GMA copolymer (PHG) was crosslinked in the presence of N,N'-dimethylacrylamide (DMAA) or N,N'-ethylenebisacrylamide (EBA). 5-fluorouracil was incorporated into PHG-DMAA or PHG-EBA beads both during and after the crosslinking process. Swelling studies revealed a high affinity toward aqueous medium, influenced by the presence of 5-fluorouracil. The in vitro release study showed that the release rate depends on the chemical structure of the beads…

INDICATORI DI PH IN VIVO CONTENENTI ANTOCIANI E LORO USO

2009

Anàlisi crítica d’aplicacions de lectura per a infants: paràmetres i indicadors

2018

Les aplicacions de lectura digital infantil han evolucionat considerablement al llarg dels últims anys. Tanmateix, segueixen sent les grans oblidades en informes i estadístiques sobre la producció editorial i més encara dins del sector digital, cosa que origina un fenomen d’infoxicació en què el mediador es troba amb pocs criteris que faciliten la selecció d’aquest nou tipus de continguts. Aquesta investigació presenta els resultats de l’anàlisi de tretze aplicacions de lectura en les seues dimensions de forma i contingut. Alhora, s’hi observen trets com ara el mode d’adquisició, la privacitat, l’organització de continguts o la personalització. Finalment, reflexionarem sobre l’adequació del…

A PERFORMANCE-BASED TOOL FOR PRIORITISING WATER METER SUBSTITUTION IN A URBAN DISTRIBUTION NETWORK

2011

User water consumption is usually measured by volumetric water meters. Water meters also provide indispensable data used by the utilities for issuing bills, obtaining the system water balance, identifying failures in the network, water theft and anomalous user behaviour. Therefore, the utilities rely on such instruments for the technical and economic management of water systems. Despite their importance, water meters are characterised by relevant intrinsic errors that are responsible for a part of so-called apparent losses, i.e. water volumes reaching a final user without being accounted for. The aim of this paper is to provide a water meter management tool that analyses the meters performa…

Overview of pesticide use in Moroccan apple orchards and its effects on the environment

2021

International audience; The cultivation of apple trees needs to use phytosanitary products, which are used in an irrational way by certain farmers. The harmful effects of pesticides result mainly from their persistence in the environment. Several studies have been carried out to estimate the pesticide residues and assess their effects on soil microorganisms and aquatic organisms. The results of these studies have revealed a harmful effect on these bioindicators. Therefore, a disruption in their growth and reproduction, an increase in their mortality, and a decrease in their fertility have been proven. In addition, a considerable reduction in the number and diversity of soil microorganisms a…

Artificial neural network decision support tool for assessment of the energy performance and the refurbishment actions for the non-residential buildi…

2017

The public buildings sector represents one of the most intensive items of EU energy consumption; the application of retrofit solutions in existing buildings is a crucial way to reduce its impact. To facilitate the knowledge of the energy performance of existing non-residential buildings and the choice of the more adequate actions, Public Administrations (PA) should have the availability of proper tools. Within the Italian project "POI 2007-13", a database and a decision support tool, for easy use, even to a non-technical user, have been developed. A large set of data, obtained from the energy audits of 151 existing public buildings located in four regions of South Italy have been analysed, …