115
11 Creating an Oven Temperature Program
11.2
11.
GC-2014
11.2 Temperature Programs
11.2.1 Isothermal analysis
The isothermal analysis technique keeps the column oven temperature at a constant value.
This method is useful for separating compounds within a narrow boiling point range.
11.2.2 Programmed analysis
When the sample contains compounds over a wide boiling point range, isothermal analysis
is irsufficient for separating all the compounds. At lower temperatures, the high boiling point
compounds will co-elute with wide peaks. Low concentrations of high boiling point com-
pounds may never be detected. On the other hand, at a higher temperatures, the com-
pounds with a low boiling point will co-elute too rapidly.
There is an optimal temperature for separating various compounds. Using an oven tempera-
ture that increases gradually controls the elution, and improves the separation, of all the
compounds.
11.2.3 Creating a temperature program
Q Screen terminology
1-ramp temperature program
Initial setting (TEMP)....T1
Initial setting hold time (TIME)..... a
Program rate (RATE)....
Final temperature (TMP)...... T2
Final temperature hold time (TIM)....... c
Equilibration time (ETIM).....
d
Column oven
temperature
Time
T2
T1
a
c
d
b
Program
starts.
Program
finishes.
T2-T
1
b
To Next Page
Loading...
Need help?
General
