Search results for "solid"

Glass-forming derivatives of 2-cyano-2-(4H-pyran-4-ylidene) acetate for light-amplification systems

2019

Abstract A series of 2-cyano-2-(4H-pyran-4-ylidene) acetate derivatives with triphenyl and 9H-carbazole moieties were synthesized and investigated, mostly for potential applications in organic solid state lasers. Synthesized compounds show remarkable amorphous film formation ability, tunable thermal properties (thermal stability varies from 190 °C to 387 °C and glass transition temperature from 94 °C up to 141 °C) with light absorption from 400 nm to 600 nm and photoluminescence from 600 nm up to 800 nm. Dyes with incorporated mono-styryl- electron donating fragment (KTB, KTBC and KTB3K) showed higher photoluminescence quantum yield (PLQY) (from 16% up to 23%), significantly lower amplified…

Emissions of Greenhouse Gases and Climate Politics in the Latvian Waste Sector

2015

According IPCC guidelines for determination of greenhouse gases in waste management (IPCC 2006) the quantity of greenhouse gases must be determined for the emissions of CO2, CH4, N2O for such treatment activities: disposal of solid waste, biological treatment of solid waste and incineration and open burning of waste. Presented report reviles the current situation of this field in Latvia and conclusions on its minimization actions. The data received from Latvian environmental data bases shows that the quantity of disposed unsorted municipal waste is rising and created sanitary landfill system with anaerobic digestion of bio mas (the content of it in the disposed waste reaches 40–50 %) is pro…

MISURA DELLA CONCENTRAZIONE DI SOLIDI PARTICELLARI IN SISTEMI SOLIDO-LIQUIDO AGITATI MEDIANTE LASER PULSATO E ANALISI DI IMMAGINI

2008

Development of LIBS for online analysis of solid nuclear materials

2015

With the objective to implement a fast, online analysis technique for control of solid metal nuclear materials, laser-induced breakdown spectroscopy (LIBS) technique is developed for quantitative analysis in uranium and plutonium. Since these matrices have a very dense emission spectrum in the UV-Visible range, the Vacuum Ultra-Violet (VUV) spectral range, less rich in lines, is explored. The aim of this thesis is to perform the analytical development of VUV-LIBS for quantitative analysis between 500 and 5000 ppm with an uncertainty of 3%. For that purpose, four steps were defined. First, for practical and safety reasons, it is generally better to perform experiments on surrogate materials.…

Selective determination of trimethylamine in air by liquid chromatography using solid phase extraction cartridges for sampling.

2004

Abstract The selective determination of trimethylamine (TMA) in air by liquid chromatography is reported. Sampling is effected by flushing air through C18-packed solid-phase extraction (SPE) cartridges at a flow rate of 15 mL/min for 15 min. Next, TMA is desorbed from the cartridges and injected into the chromatographic system. The analyte is then selectively retained on a precolumn ( 20 mm ×2.1 mm i.d., packed with 30 μm, Hypersil C18 phase), and derivatized on-line by injecting 9-fluorenylmethyl chloroformate (FMOC). Finally, the TMA-FMOC derivative is transferred to the analytical column ( 125 mm ×4 mm i.d., LiChrospher 100 RP18, 5 μm), and monitored at 262 nm. The method was applied to …

Application of solid-phase microextraction combined with derivatization to the determination of amphetamines by liquid chromatography

2004

This work evaluates the utility of solid-phase microextraction (SPME) in the analysis of amphetamines by liquid chromatography (LC) after chemical derivatization of the analytes. Two approaches have been tested and compared, SPME followed by on-fiber derivatization of the extracted amphetamines, and solution derivatization followed by SPME of the derivatives formed. Both methods have been applied to measure amphetamine (AP), methamphetamine (MA), and 3,4-methylenedioxymethamphetamine (MDMA), using the fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) and carbowax-templated resin (CW-TR)-coated fibers. Data on the application of the proposed methods for the analysis of different kin…

Extraction and Sample Preparation

2015

As everyone knows, the role played by extraction and sample preparation in the analytical sciences cannot be overemphasized. Despite tremendous advances in chromatography, detection, and other aspects of analysis, extraction and sample preparation remain a preanalysis ritual of critical importance. It has been estimated that around 50% to 70% possibly even more of the time and effort that goes into an analytical process comprises extraction and sample preparation. Sample preparation procedure can vary in the degree of selectivity, speed, and convenience, depending on the approach and conditions used, as well as on the geometric configurations of the extraction phase and conditions. Proper d…

In tube-solid phase microextraction-nano liquid chromatography: Application to the determination of intact and degraded polar triazines in waters and…

2017

Abstract In-tube solid-phase microextraction (IT-SPME) coupled to miniaturized liquid chromatography (LC) techniques are attractive mainly due to the column efficiency improvement, sensitivity enhancement and reduction of solvent consumption. In addition, the nanomaterials based sorbents can play a key role in the improvement of the extraction efficiency taking into account their interesting physical and chemical properties. Thus, in this work the performance of IT-SPME coupled to nano LC (NanoLC) has been compared with the performance of IT-SPME coupled to capillary LC (CapLC) with similar configurations for the determination of polar triazines including their degradation products. In both…

Amphetamine-type stimulants analysis in oral fluid based on molecularly imprinting extraction

2018

Abstract A methamphetamine-based molecularly imprinted polymer (MIP) has been prepared by bulk polymerization to recognize new psychoactive substances (NPS) of the amphetamine, cathinones and 2C families in oral fluid samples, being the first precedent of a synthetized MIP for the extraction and preconcentration 32 NPS including amphetamine type substances and synthetic cathinones from oral fluids. Pre-polymerization complex and resulting materials were appropriately characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. Appropriateness of the material for the specific recognition of the target analytes was also evaluated through …

Adsorbent phases with nanomaterials for in-tube solid-phase microextraction coupled on-line to liquid nanochromatography

2015

Following the present trends in miniaturization, a methodology that combines on-line In-Tube Solid-Phase Microextraction (IT-SPME) with Liquid Nanochromatography (nano-LC) and UV-vis diode array detection (DAD) was developed. This coupling was achieved by using two interconnected valves (i.e. conventional and micro-automatic valves) in the system of injection. As for IT-SPME, different materials, containing in some cases nanostructures or nanoparticles and in other cases polymeric adsorbent phases immobilized on capillary columns, were tested in order to improve extraction efficiencies of organic compounds; diclofenac was selected as the target analyte. Additionally, the transfer time of th…