We have an older Shimadzu system which requires activating each pump on its respective control panel additionally to activating them in the software.

You did not tell much about the conditions, so I assume that an intact column is in the flow line, a flow rate is set that would normally cause significant pressure with that column, and that no or hardly any actual flow is produced.

If it is sure that the pumps are operating but still don't build up pressure, I would recommend to do the following steps until you have pressure and a correct actual flow rate (check after each step):

You could also have a broken pressure sensor if you have no pressure while solvent is pumped through the column at a significant flow rate.

Hi Faith,

did you checked the whole system? Restarted the PC? Do you have a leak somewhere? Is liquid coming out of the pump unit when it is on? Could be the rubber seals of the pump heads which may be broken. You give too less information on the solvent system you use.

Good luck,

Marcus

Check for leakage 

We have an older Shimadzu system which requires activating each pump on its respective control panel additionally to activating them in the software.

You did not tell much about the conditions, so I assume that an intact column is in the flow line, a flow rate is set that would normally cause significant pressure with that column, and that no or hardly any actual flow is produced.

If it is sure that the pumps are operating but still don't build up pressure, I would recommend to do the following steps until you have pressure and a correct actual flow rate (check after each step):

You could also have a broken pressure sensor if you have no pressure while solvent is pumped through the column at a significant flow rate.

Sorry for providing little explanation on the problem.

We cleaned the column (C18) with 0.05M, 2%acetic acid/ water at flow rate of 0.01mL/min overnight. Then our technical staff was attempting to re introduce the mobile phase as she was analysing catechins with mobile phase A:89:9:2 (water: acetonitrile: EDTA) in 20ug/ml glacial acetic acid ; B: 18:80:2 (water: acetonitrile: EDTA) in 20ug/ml glacial acetic acid. She introduced it at flow rate of 0.01mL/min, A: 100% for 25min, gradient to 32% for 10min the back 100%. When she changed the flow rate to 1mL/min the pressure overshoot, then went down to 0.9MPa and it never rise again even by change of the flow rates. There is no leakage so afar. I checked the solvent flow and realize that, the flow to pump inlet but not solvent in the pump outlet. So no solvents to the auto sampler even the column.

Please check the purging nob whether that is properly closed, if there is no leakage. Are you using this specified flow rate? I think even you should try with more flow rate.

Please follow the steps suggested by Jandrik.

Regards

 Have a look on this troubles shooting for HPLC: 

https://www.google.it/url?sa=t&source=web&rct=j&url=https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Supelco/Bulletin/4497.pdf&ved=0ahUKEwjE2LmW79bTAhVsJ8AKHRLWAPAQFgghMAA&usg=AFQjCNF7Xl27_gtdl2i0ugEjts4I03w-kw&sig2=SSJCQA5StjDUdjTWAPtcPQ

Regards

Also this paper:

https://www.google.it/url?sa=t&source=web&rct=j&url=https://www.researchgate.net/file.PostFileLoader.html%3Fid%3D51d81086d039b1bf6a7b0590%26assetKey%3DAS%253A272186256887816%25401441905668236&ved=0ahUKEwjE2LmW79bTAhVsJ8AKHRLWAPAQFggsMAE&usg=AFQjCNGvE2I3vCcLvCkm0uNF0qr2LCGa0Q&sig2=DG9QkVHqvHO42iCbZvBVMA

Regards

Dear Jandirk and others thank you for advice, I am going to try follow the procedures, and will come back for results.

I think once verify the tubings also. I remember it happened once with my colleague when he was doing his study a solvent got precipitated in solvent supply tubings which completely stopped the solvent supply to the system. Ask your technician to check the tubings and pump channel. You can try with another pump. I mean if A is blocked can check with B supply tubing.