I have a HP HS method with inj time 1 min.
Since HP HS has a loop , inj time doesnot matter.
Then what should be the optimum inj time.
What should be the conditions in PE , regarding inj. time
MY column flow rate is 10 ml/min while my vial pressure in HP is 11.8 psi.
By John Hinshaw on Tuesday, January 16, 2001 - 08:04 am:
The PE HS-xx headspace sampler injects by taking the column flow from the HS vial for the method's injection time period. The default injection time is 0.02 minutes (1.2 s) which produces a nice sharp injection profile without the need for trapping and sharpening peaks on the column, i.e. for isothermal elution. However, at your 10 mL/min flow rate, this amounts to only 0.2 mL injected. If you need more volume, then you'll need to increase the injection time.
The PE HS samplers can be programmed to make injections on a volume basis, in the configuration screen (depends on the model). Set that mode, enter the column flow rate there, and then select the injected volume in the method. A 1-mL injection would take 0.1 minutes, in your case. Now, however, the initial peak widths are probably too large for a capillary column, so you should use a temperature programmed method that starts cool enough to trap and sharpen the peaks at the column entrance. An initial temperature of about 40 °C below the first peak's elution temperature should do.
Note also that the vial pressurization level must be greater than the "native" pressure in the vial after thermostatting and equilibration.
Please contact me by email if you'd like further assistance.
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