Search results for "Liquid phase"

Gas-liquid chromatographic analyses

1983

Abstract The gas chromatography of mixtures of n -alkyl acetates (CH 3 COOR, R = C 1 —C 8 ) and methyl esters of aliphatic n -carboxylic acids (R′COOCH 3 , R′ = C 1 —C 8 ) and certain of their monochlorinated derivatives has been studied on Carbowax 20M and SE-30 glass capillary columns under the same operating conditions. The separation of the isomeric monochlorinated esters was complete on Carbowax 20M, whereas on SE-30 the peaks of 6- and 7-chlorooctyl acetates and methyl (ω − 1)- and (ω − 2)-chlorooctanoates and -nonanoates partly overlapped. The complete separation of the mixtures could not be achieved, however, on Carbowax 20M, in spite of the use of various operating conditions. The …

Application of a low transition temperature mixture for the dispersive liquid–liquid microextraction of illicit drugs from urine samples

2021

© 2021 by the authors.

Passive exposure to nicotine from e-cigarettes

2016

A procedure based on the use of ion mobility spectrometry (IMS), after liquid-liquid microextraction (LLME), has been successfully employed for the determination of passive exposure to nicotine from cigarette and e-cigarette smoking. Nicotine has been determined in exhaled breath and oral fluids of both, active and passive smokers. The aforementioned studies, made in closed environments, evidenced that the exhaled breath after conventional blend cigarette smoke provides nicotine levels of the order of 220 ng per puff, in the case of experienced smokers, being exhaled only 32 ng in the case of e-cigarettes. On the other hand, the nicotine amount in oral fluids of passive vapers was between 8…

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…

Ein schnelles on-line trennsystem unter anwendung von helium-jet- und zentrifugentechnik

1975

Abstract A centrifuge for continuous liquid-liquid phase separation is described. It is designed for rapid solvent extraction of short-lived radioactive isotopes (half-lives in the order of seconds). The centrifuge is characterized by simple construction and operation principle, easy handling, low cost, and a minimum hold-up time of less than five seconds (phase purity 99.0–99.9%). The on-line connection to a helium-jet transport system is described. Problems concerning the transfer of activities into a liquid phase from the helium-jet at atmospheric pressure are discussed.

Gas-liquid chromatographic analyses of chlorination products of propionyl chloride

1981

Abstract Photochlorination of propionyl chloride with chlorine in the liquid phase at room temperature gives all eleven chloropropionyl chlorides from the mono-to the pentachloro isomer. The process was investigated every 2 h by gas-liquid chromatography, and the products were identified and estimated as their methyl esters by comparison with model compounds. The isomer distribution of the products was studied in detail. Because the process favours the 3-position, the main components were 3-chloropropionyl chloride up to 15 h, 3,3-dichloropropionyl chloride between 15 and 29 h, 3,3,3-trichloropropionyl chloride between 29 and 56 h and pentachloropropionyl chloride after 56 h of chlorination.

Molecular connectivity as a relevant new tool for predicting analytical behavior: A survey of chemiluminescence and chromatography

2005

Abstract We present a critical presentation and discussion on molecular connectivity applied to analytical fields, giving special attention to predicting the chemiluminescent behavior of pharmaceuticals and pesticides. Molecular connectivity has been largely applied to predict the therapeutic effects of pharmaceuticals and rarely to predictions in analytical chemistry – basically to chromatographic processes and recently to liquid-phase chemiluminescence.

Liquid-phase Chemistry

2003

Sample Preparation to Determine Pharmaceutical and Personal Care Products in an All-Water Matrix: Solid Phase Extraction

2020

© 2020 by the authors.

2017

Computer simulations are used to model the phase change that occurs as glasses transition from a liquid phase to a so-called ``ideal glass phase.''