HT2800T_en_c.doc Page 149 of 275
because the vial may sit too long while waiting for the GC to become Ready. It is better to enter
a longer time than needed than to enter too short a time and possibly reduce sample quality.
To determine the analysis time, program the GC to perform a sequence of two or three blank
(no injection) runs. If you are using a Data system, you can determine the cycle time from the
data system sequence log and compare the start times for the runs. A good analysis time is the
average difference between the start times, plus 0.2 to 0.5 minutes. If you are not using a Data
system, watch the GC. Count the time between the start of the first run and when the GC
becomes Ready for the second run, then add 1 minute.
You can also estimate the analysis time without making a run. By adding the GC oven program
duration and the duration of any post-run programs, you can get close to the true cycle time.
Also consider time for data processing. While in most cases data processing is not a problem, a
very busy Data system may need extra time between samples.
To validate the analysis time, look at the GC run time. The analysis time cannot be less than the
total run time. Then look at the GC post run program duration. The analysis time cannot be less
than the total run time plus the post run program duration.
Finally, consider that the GC cooling time may vary according to room temperature: the higher
the room temperature is the more time is needed for the GC cooling time; typically it implies a
shorter time during winter seasons and a longer time during summer seasons. Therefore, the
analysis time should be set according to the worst scenario (summer season).
5.3.2.2 Conditioning parameters
Access sequence: RUN>SETTINGS>METHODS>METHOD X>CONDITIONING
The following parameters can be viewed/edited:
•
Oven Temperature: temperature of conditioning of the oven. This value can be between
40°C and 170°C or off (inactive conditioning);
•
Incubation: sample incubation time inside the oven;
•
Shaker On: interval time during incubation time in which the sample is shaken;
•
Shaker Off: interval time during incubation time in which the sample is not shaken.
Select “Exit” to exit from this screen and return to the “RUN: METHOD X” screen (see
paragraph 5.3.2 “Method X: Setting method parameters“).
5.3.2.3 Wash & Clean parameters
Access sequence: RUN>SETTINGS>METHODS>METHOD X>WASH & CLEAN
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