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ask for the HPLC pressure reference?
Posted: Thu Dec 05, 2013 11:16 am
by Mya Gao
1.when testing the HPLC experiment, how to judge whether the pressure is normal, what is the range of the pressure?
2. what is the difference between the Agilent and the Waters about the HPLC pressure?
3. who has the reference about the range HPLC pressure?
Best regards!
Re: ask for the HPLC pressure reference?
Posted: Thu Dec 05, 2013 4:01 pm
by AA
1.when testing the HPLC experiment, how to judge whether the pressure is normal, what is the range of the pressure?
There is no "normal". The pressure is dependent on several factors, flow rate, column i.d., column length, solvent composition, temperature, tubing i.d., detector flow cell dimensions, adn probably a few others.
2. what is the difference between the Agilent and the Waters about the HPLC pressure?
Both companies make numerous instruments each having its own pressure limit specification, check the specs on the Waters or Agilent website for you exact model.
3. who has the reference about the range HPLC pressure?
The best place to get this info is from each company.
Re: ask for the HPLC pressure reference?
Posted: Fri Dec 06, 2013 12:11 am
by tristanewalters
If you are talking about the "workhorse" HPLCs of each company, Waters has the Alliance and Agilent has the 1100 series (I believe). Typical default maximum backpressure for these systems are 4000psi for the Waters and 400bar (about 5800psi) for the Agilent.
As AA said, there isn't an across the board "normal" for column pressures. You adjust your instrument parameters for whatever column you are using (flow rate, column temperature, and instrument tubing can have substantial impact on pressure) if you have to use a specific column. In general, 5 um and 3um particle size in columns work well for HPLC. You may begin to see high pressure issues if you try using 1.8 um particle sizes. These are better used for UHPLC, in general of course.
Re: ask for the HPLC pressure reference?
Posted: Fri Dec 06, 2013 6:00 pm
by uzman
Regarding the columns , to be on the safe side , do not exceed 250-300 bar for silica based columns , and adjust flow if necessary.
Over 300 bar operation for a long time , the column performance may drop drastically.
Polymer based columns requires even lower backpressures.
As a practical example , with a 70%methanol +30%water mobile phase at 1 ml/min flow , a 250 x 4.6mm column with 5ยต particles , gives around 100 -120 bar backpressure.