Vapours

About: Vapours is a research topic. Over the lifetime, 1153 publications have been published within this topic receiving 15022 citations.

The development of optical chemical sensors for the detection of volatile compounds from spoiled hams

Abstract: The vapours from Spanish dry-cured hams are being sampled by an array of different chemical sensors to assess the quality of the hams during the curing process. Some of the sensors analyse the concentration of sulphur-containing compounds in the vapours, as the presence in higher concentrations of these compounds has been identified as one of the factors indicating the spoilage of hams. The paper describes an optode membrane fabricated by immobilizing tetraoctylammonium fluorescein mercuric acetate (TOAFMA), tetraoctylammonium hydroxide and tributyl phosphate into a polymeric support (ethyl cellulose) to detect certain sulphur-containing compounds in the vapours from the hams. The fluorescence of the TOAFMA is irreversibly quenched by the sulphur-containing compounds in the vapours from the hams. It is observed that over a fixed time interval, the vapour from a bad ham causes a greater fluorescence quenching effect than that from a good ham and the longer the exposure time, the greater is the response of the membranes to the ham vapours. The compound dimethyl disulphide (DMDS) is used to investigate the response characteristics of the optode membranes. A flow rig for producing mixtures with accurately known concentrations of DMDS in nitrogen gas is also described. This system could be easily adapted to work with any volatile liquid.

Composition and conductivity of a copper-air plasma

Abstract: The composition as well as the electric and thermal conductivities of a copper-air plasma at atmospheric pressure are determined for temperatures ranging from 5000K to 14000K and different values of copper content. The calculating procedure is indicated and through an analysis of the results it is shown that the characteristics of the medium can be modified quite significantly in the presence of metal vapours.

The antibacterial action of anaesthetic vapours

Abstract: SUMMARY The antibacterial action of the vapours of the volatile anaesthetic agents on E. coli has been investigated. Known numbers of organisms were exposed to various concentrations of halothane, chloroform, trichloroethylene, methoxyflurane, and diethyl ether, under controlled conditions of humidity and oxygen concentration. It was found that these agents reduced the survival of the organisms to an extent which was generally proportional to the concentration of agent used. The implications of these findings are discussed.

Polymerized linseed oil coated quartz crystal microbalance for the detection of volatile organic vapours

Abstract: Quartz crystal microbalance (QCM) sensors are developed from polymerized linseed oil and used for the detection of volatile organic compounds (VOCs) such as p-cresol, o-xylene, benzene, and toluene. The polymer film on QCM surface is synthesized from the free radical polymerization of linseed oil in chloroform using benzoyl peroxide as initiator by dip coating method. The sensitivity, stability and selectivity of the sensors are measured by exposing the QCM surface to vapours. The synthesis of films are optimized and is found to have maximum adsorption of vapours when it is polymerized with 1.7% (w/v) of benzoyl peroxide. Among these four types of vapours, the maximum sensitivity is found with p-cresol and frequency shift of 110 Hz is obtained for 250 ppm of p-cresol vapour in nitrogen atmosphere. The sensor responses of concentration ranges from 5 to 250 ppm are found to be linear. The structure of the polymeric films is confirmed by FTIR analysis. Surface morphologies of the films before and after absorption are studied using AFM. The sensors are reactivated by releasing the adsorbed vapour by passing dry nitrogen gas. The sensing responses of VOC are observed to be substantial and reproducible.