摘要:

The term 'ion-selective electrodes' is applied to a range ofmembraneelectrodes which respond selectively toward one (or several) ionic species in the presence of others. The less-preferred term 'ion-specific' is not favored1because these electrodes are rarely specific in their response to one ionic species over others, although this is a desirable property sought by the designer of new electrodes. The descriptionmembraneis used here in its broadest sense to denote a thin section of electrically conducting material separating two solutions and across which a potential develops. Often the termmembranehas associated with it the notion of permeability to a species present in the flanking solutions. However, although this is undoubtedly true with certain porous biological and synthetic membranes, the actual mechanism of electrical conduction in general varies with the type of membrane material; indeed it may change within it.

ISSN:0007-8980    

DOI:10.1080/10408347308542665

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Chloramine-T, the sodium salt ofN-chloro-p-toluenesulfonamide, was first prepared by F. D. Chattaway in 1905.1In 1924, A. Noll2proposed its use as a substitute standard reagent in place of the more expensive iodine standard. Since 1924, there have been more than one hundred papers published on its application in analytical chemistry.

ISSN:0007-8980    

DOI:10.1080/10408347308542666

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The determination of metabolites in human body fluids requires the development of analytical methods capable of providing both quantitative and qualitative information for a relatively large number of compounds, notably steroids, in complex mixtures. Prior to 1955, work on the isolation and identification of steroids had employed solvent partition, adsorption chromatography, digitonin precipitation, the use of Girard reagents, and a number of other techniques more common in organic chemistry. Despite the obvious progress that these techniques had made possible in the steroid field, it was apparent that other concepts would be needed in order to develop specific and quantitative methods for the determination of steroids in biological samples and especially for the determination of the relatively low concentrations of steroid hormones in blood and urine.

ISSN:0007-8980    

DOI:10.1080/10408347308542667

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Microwave spectroscopy is concerned with the observation and analysis of transitions between molecular rotational energy levels. These transitions fall within the segment of the electromagnetic spectrum called the microwave region. This region lies between the conventional radio wave region and the infrared region and extends from frequencies around 1,000 MHz (λ=30 cm) to around 1,000,000 MHz (λ=0.3 mm). In this spectral region, it is common practice to express frequencies in megahertz (MHz) or gigahertz (GHz), where the Hertz (Hz) unit denotes cycles per second, 1 MHz=106Hz, and 1 GHz=109Hz. The region may be further divided into the centimeter-wave (λ= 1 to 30 cm), millimeter-wave (λ=1 to 10 mm), and submillimeter-wave regions (λ< 1 mm). Whereas the infrared region is associated with the phenomena of molecular vibrations, the microwave region is associated with molecular rotations. Microwave spectroscopy usually implies gas-phase molecular rotational spectroscopy, though other areas of spectroscopy, such as EPR, operate in the microwave region. The term molecular rotational resonance (MRR) spectroscopy has also been applied.

ISSN:0007-8980    

DOI:10.1080/10408347308542668

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor