By Anonymous on Wednesday, February 16, 2000 - 12:31 am:
We have a problem with high pressure on HPLC: Nucleosil C18, 5 microns, 25cmx0.46cm with a mobile phase consisting of:
A : MeOH/Acetonitrile/Water 400/35/565
B: MeOH/Acetonitrile/Water 800/35:165
with a gradient programme
initial 95%A
20 min 50%A
25min 30% A
The back pressure rises from 230 bar to more than 300 bars after some analyses. The problem comes probably from the high viscosity of the mixture MeOH/water 40/60.
By Steve on Wednesday, February 16, 2000 - 02:46 am:
What is your flow rate? I assume it is 1 mL/min. 230 bar seems a little high. What does your pressure read before column? If you perform an injection with the column off, what is your pressure profile like? Are you using PEEK tubing and fittings? Sometimes the end of the tubing gets crimped by the fitting if not installed properly. This will make your pressure shoot up.
By Anonymous on Wednesday, February 16, 2000 - 05:56 am:
The pressure will increase and according to me there is no remedy to it.You have to either change the method or stay with the constraints of the method.
By lisa on Wednesday, February 16, 2000 - 10:53 am:
What kind of samples are you injecting? You might have junked up the frit at the head of the column.
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