Search results for "IMPR"
showing 10 items of 1334 documents
Synthesis and sorptive properties of molecularly imprinted polymer for simultaneous isolation of catecholamines and their metabolites from biological…
2021
Simultaneous quantitative analysis of catecholamines (CAs) and their respective acid metabolites in biological fluids can become a powerful tool for diagnosis and treatment of various diseases. However, selective sample preparation procedure is necessary to isolate the aforementioned analytes from the matrix. Therefore, we propose a synthetic strategy for the preparation of a molecularly imprinted sorbent with binding sites for both CAs and their respective acid metabolites. The synthesis combines noncovalent and semicovalent imprinting methods. Methylenebisacrylamide, 4-vynilbenzyl-N,N,N-trimethylammonium (3,4-dimethoxyphenyl)acetate, and 3-phenylpropylacrylate were used as the cross-linke…
Influence of template basicity and hydrophobicity on the molecular recognition properties of molecularly imprinted polymers
1996
Abstract Triazine herbicides were used as model templates for a basic study of the molecular recognition process in imprinted polymers. Five structurally related triazine herbicides (atrazine, ametryn, cyanazine, prometryn and terbutylazine) that differ in basicity and hydrophobicity were imprinted. Chromatographic evaluation of the resulting materials in an aqueous-poor mobile phase showed that the selectivity for the template increased with its Bronsted basicity whereas it did not correlate with template hydrophobicity. Thus, the highest and lowest affinity and selectivity for the template was observed using the ametryn-imprinted (p K a =4.1) and the cyanazine-imprinted polymers (p K a =1…
Extraction of clenbuterol from calf urine using a molecularly imprinted polymer followed by quantitation by high-performance liquid chromatography wi…
2002
A method for the extraction of clenbuterol from calf urine samples using a molecularly imprinted polymer (MIP) has been developed. The aim was that the final extracts from the MIP should allow quantitation of clenbuterol down to 0.5 ng/mL urine using HPLC with UV detection. The MIP was produced using brombuterol as a template and the selectivity of the MIP, for clenbuterol, was tested against a non-imprinted polymer (produced without template) and was found to be high. After loading of 5 mL diluted centrifuged urine, selective binding was established in acetonitrile-acetic acid (98:2). For further elution of interferences, 0.5 M ammonium acetate buffer pH 5 and 70% acetonitrile in water was…
Methodisches zur bestimmung der molekulargewichtsverteilung von cellulosen
1959
Es wird eine verbesserte Fallungs-Fraktioniermethode zur Ermittlung von Molekulargewichtsverteilungen an Cellulosenitraten beschrieben. Es konnen mit ihr gut reproduzierbare Verteilungskurven erhalten werden, wenn man die notwendigen Bedingungen wie gleichmasige Substitution des Praparates, moglichst kleine Ausgangskonzentration zur Erreichung eines guten Trenneffektes, Vermeidung eines Abbaues wahrend der Fraktionierung usw. in genugender Weise beachtet, – Zur Auswertung der Fraktionierergebnisse raumlich inhomogener Praparate (wie z. B. merzerisierte und oxydativ abgebaute Baumwollen) wird ein statistisches Verfahren vorgeschlagen. An improved method of preciptation fractionation for dete…
Molecularly imprinted polymer-based device for field collection of oral fluid samples for cocaine identification.
2020
In this paper, a low-cost, rapid, easy, and potentially portable tool for the identification of cocaine and its semi-quantitative determination in oral fluid has been proposed. A field collection device has been designed, based on a cotton pad with an indicator and a molecularly imprinted polymer (MIP) sorbent, to selective retain cocaine from oral fluid components. After sample collection, cocaine is transferred by using phosphate buffer to the MIP and then eluted with 2-propanol. The obtained extract is analysed by ion mobility spectrometry (IMS), providing a cut-off value of 20 µg L-1 that identifies 100 % true-positive and 95 % true-negative samples. The MIP-IMS procedure has been valid…
Study of Chromatographic Properties of Catecholamines and their Acidic Metabolites Using Novel Molecularly Imprinted Polymers as Stationary Phases
2021
Quantitative analysis of catecholamines and their acidic metabolites can provide vital information for diagnosis and treatment of various diseases (such as adrenal tumors). However, complicated purification protocols are usually required to isolate the analytes. Molecularly imprinted polymers (MIPs) have attracted considerable attention as a method of selectively separating desired compounds from their matrix. Therefore, we propose a synthetic procedure for new molecularly imprinted sorbents that possess selective binding sites for both catecholamines and their acidic metabolites. The new polymer utilizes non-covalent and semi-covalent imprinting methods. The binding properties of MIPs were…
Effect of solvents on the selectivity of terbutylazine imprinted polymer sorbents used in solid-phase extraction
2002
A solid-phase extraction sample preparation method using a molecularly imprinted polymer (MIP) selective for the triazine type pesticide terbutylazine has been developed. The method involves preconcentration from large volumes of water samples on a C18 disk coupled to selective clean-up on the MIP. The method has been optimised by studying the recovery and retention of terbutylazine and some other structurally related triazine derivates as a function of the selective washing solvent used. The effect of the water content of the selective washing solvent was also investigated on the recovery of the MIP. River water samples were analysed with the coupled technique, and efficient clean-up of th…
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
2010
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…
LIFE CYCLE ASSESSMENT OF ITALIAN CITRUS BASED PRODUCTS. SENSITIVITY ANALYSIS AND IMPROVMENT SCENARIOS
2010
Though many studies concern the agro-food sector in the EU and Italy, and its environmental impacts, literature is quite lacking in works regarding LCA application on citrus products. This paper represents one of the first studies on the environmental impacts of citrus products in order to suggest feasible strategies and actions to improve their environmental performance. In particular, it is part of a research aimed to estimate environmental burdens associated with the production of the following citrus-based products: essential oil, natural juice and concentrated juice from oranges and lemons. The life cycle assessment of these products, published in a previous paper, had highlighted sign…
A class of imprimitive groups
2010
We classify imprimitive groups inducing the alternating group A4 on the set of blocks, with the inertia subgroup satisfying some very natural geometrical conditions which force the group to operate linearly.