Separation of analytes

Separation of analytes - context
Analyte mixtures and separation - 1
Analyte mixtures and separation - 2
Analyte mixtures and separation - 3
Introduction to chromatography
Chromatographic columns
Principle setup of a chromatographic unit
Example of separation
Chromatographic system - 1
Chromatographic system - 2
Standard gas chromatograph
(Old) liquid chromatography unit
(New) liquid chromatography unit
HPLC columns
Comparison GC and HPLC
Selftest
     1) Purpose of chromatographic process
           Answer
     2) Unsuitable compounds
           Answer
     3) HPLC vs. GC
           Answer
     4) Detectors
           Answer
     5) Solvent properties
           Answer
     6) Retention time
           Answer
     7) Analyte identification
           Answer
     8) Irreversible or reversible sorption process
           Answer
     9) Short analysis time
           Answer
     10) Retention factor
           Answer
     11) Breakthrough-curve
           Answer
Problems
End of lesson

10) Retention factor

 

Question:

How does the retention factor in a filter, chromatographic system or soil column change if ...

10 a) ... the partition constant Ki mobile phase/ stationary phase increases?

10 b) ... the porosity increases?

10 c) ... the temperature increases?

 

Answer:

10 a) The retention goes down because the partition preference for the mobile phase increases.

10 b) The retention goes down because as the relative volume of mobile phases increases, the fraction of the analyte in the mobile phase will also increase.

10 c) If the mobile phase is gaseous, retention will go down. If the mobile phase is a liquid then no general answer is possible.