摘要:

Methods used for trace (sub-ppm) detection of mercury are reviewed. Included are spectrometric methods such as atomic absorption, fluorescence, emission, and mass spectrometry; electrochemical methods; and as radiometric methods as well as other common and novel techniques. Limits of detection are reported where given, and advantages and disadvantages are compared.

ISSN:1040-8347    

DOI:10.1080/10408349708050578

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

It is likely that 90% of all small-molecule high-performance liquid chromatography (HPLC) separations can be done with a hydrocarbon-bonded phase of C4, C8, or C18 length using various mobile phases. The remaining 10% of the cases are more challenging. One solution is to follow the historical path of gas-liquid chromatography and create more bonded phases. The second and more easily done is to add components to the mobile phase that interact selectively with the molecules of interest and change RPLC selectivity and retention. This paper begins with a generalized discussion of additive strategy and mechanism and then leads to a study of nonionic but coordinatively unsaturated (β-diketonates as additives which serves as an example of the connection between molecular chemistry and chromatographic selectivity and a review of other work done. A system of coordinatively unsaturated metal β-diketonates was investigated as mobile phase additives for HPLC. Unlike previous ionic, metal dopants, these neutral complexes combine reasonable elution times, high chromatographic efficiency, and enhanced chromatographic selectivity for polar compounds in normal and reversed-phase modes. The influences of mobile-phase composition, stationary-phase substrate, and metal on solute retention behavior were examined for the metal-dipivaloylmethane additive systems.

ISSN:1040-8347    

DOI:10.1080/10408349708050579

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We describe stick diagrams, which are simple graphs designed to provide quick insight into complicated ionic equilibria. Despite their inherent crudeness, they can be used to obtain numerical solutions to quantitative equilibrium problems. Moreover, they show when those quantitative answers are likely to be too approximate. Finally, we discuss how to make activity corrections, and conclude that activity corrections are often as large or larger than the errors involved in using stick diagrams. Therefore, in the absence of activity corrections, stick diagrams are usually quite adequate.

ISSN:1040-8347    

DOI:10.1080/10408349708050580

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1040-8347    

DOI:10.1080/10408349708050581

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1040-8347    

DOI:10.1080/10408349708050582

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor