Modern Methods of Plant Analysis / Moderne Methoden der Pflanzenanalyse (1962) (Modern Methods of Plant Analysis Moderne Methoden der Pflanzenanalyse #5)

Synopsis

123 phase and hence have no direct bearing on the retention time of solutes. However in gas-solid chromatography, a considerable quantity of the mobile phase may be adsorbed on the surface of the stationary adsorbent which diminishes the column's effective length and ability to retain solutes. In this respect helium has been found to be preferable to most other gases (GREENE and Roy, 1957) because it is adsorbed to the least extent. 3. Packed columns offer a considerable resistance to flow, which may create a pressure differential between inlet and outlet of sufficient magnitude to cause an unfavorable flow rate through a significant length of the column. A reduced inlet/outlet pressure ratio can be obtained by using light molecular weight gases toward which the column packing shows the greatest permeability. The flow rate of the mobile phase is normally adjusted by altering the column inlet pressure, for which purpose commercial pressure regulators of sufficient accuracy are available. Quantitative measurements of the flow rate can be made by a number of methods, including rotameters, orifice meters, soapfilm flow meters and displacement of water. The former two methods are the most con­ venient but the least accurate; moreover they create a back pressure and are temperature dependent whereas although the moving soap bubble is cumbersome to employ and unusable for continuous readings, it is preferred when the highest accuracy is required.

Copyright:

1962

Book Details

Book Quality:

Publisher Quality

ISBN-13:

9783642459931

Related ISBNs:

9783540028819

Publisher:

Springer Berlin Heidelberg

Date of Addition:

08/20/22

Copyrighted By:

N/A

Adult content:

No

Language:

English, French, German

Has Image Descriptions:

No

Categories:

Nonfiction, Science

Submitted By:

Bookshare Staff

Usage Restrictions:

This is a copyrighted book.