What pressure to used for a HPLC process? - (Dec/21/2006 )
Hi everyone,
I have a anion-exchange column for HPLC, which can stand up to max psi of 4000. However, how much pressure should I use on this HPLC column for a particular run. In other words, what are the factors that determine the suitable pressure used in a run? Thousand thanks with much appreciation.
haohao
I have a anion-exchange column for HPLC, which can stand up to max psi of 4000. However, how much pressure should I use on this HPLC column for a particular run. In other words, what are the factors that determine the suitable pressure used in a run? Thousand thanks with much appreciation.
haohao
If your column can take 4000 psi, try setting the maximum pressure for your system about 3500 psi. That should allow you to run at a reasonable flow rate, and have a buffer in case the pressure starts getting up a bit, without risking the column.
I Agree with swanny. There is no right pressure that is appropriate to HPLC. If you have a max of 4000 psi. then set the cutoff to 3999. This way if there is a problem i.e block in your column or a bubble in the outflow valve and the pressure rises too high, the machine can shut off automatically. This will protect your machine.
Also in the case of multiple solvents, the pressure will again vary. Acetonitrile alone will lead to a lower psi than water alone. If you are using a mixture of multiple solvents for one sample vial, the psi will vary constantly thru that run. The maximum pressure you will notice is when the machine is injecting or taking up the sample.
Hope I was of some help.
I have a anion-exchange column for HPLC, which can stand up to max psi of 4000. However, how much pressure should I use on this HPLC column for a particular run. In other words, what are the factors that determine the suitable pressure used in a run? Thousand thanks with much appreciation.
haohao
the most important factor you should consider is flow rate. you want to use a flow rate which will allow you to optimize your separation but will not exceed the pressure limit for the column. you adjust the flow rate to not exceed the ability of your apparatus to form a proper gradient, give baseline separation between components of interest (if possible) and to minimize separation time.
you can set the pressure limit at the limit of the column (it could be lower if you want but shouldn't be necessary, briefly exceeding the written limit should not damage the column and the pump will shut down to avoid extended time at high pressure).
you should keep an eye on the pressure because, mostly through contamination and (maybe) bed settling, the pressure will rise. you may have to adjust flow rate if the pressure goes too high.