To Determine The Gc Cycle Time - Agilent Technologies 7697A Operation Manual

6
Methods

To Determine the GC Cycle Time

To determine the GC cycle time

60
The HS uses the GC cycle time to calculate throughput and
timing. An accurate GC cycle time is crucial to optimizing
throughput and for correctly processing samples.
If the GC cycle time is too long, this can cause:
• Lowered throughput. Vials wait longer than needed before
processing.
If the GC cycle time is too short, this can cause:
• Sequence faults. Vials may be processed too early and
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.
The GC cycle time is the GC run time plus any additional time
needed for the GC to execute any post- run program, then
return to a ready state.
To determine the GC cycle time, program the GC to perform a
sequence of two or three blank (no injection) runs.
• If using a data system, you can determine the cycle time
from the data system sequence log. Compare the start
times for the runs. A good GC cycle time is the average
difference between the start times, plus 0.2 to 0.5
minutes.
• If 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 to 2
minutes.
You can also estimate the GC cycle 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. However, temperature programming and cryogenic
operation can make estimation more difficult. Add extra
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.
Operation