[freeze0912]

I want to ask about the pumping system of HPLC
How can I perform the flow rate repeatability of the pumping system??

[enahs]

Instead of pumping through the column, turn on the purge valve.
Set it at a flow rate, say 1mL/min, start the flow for a few second and make sure the pumps are at full speed. Get a timer and set it for 5 minutes. Start collecting the effluent into a good graduated cylinder, start the timer when you start collecting. In 5 minutes you should have 5 mL. Mark the level with a sharpe. Repeat the procedure. Does it come back up to the sharpe level the second time (within error)? Is it 5 mL within error?

If you have a dual pump system, do it with each pump individually.
And if you do a lot of gradients and work over different ranges, I would check it at different flow rates. IE. 0.5mL/min, 1mL/min, 2mL/min. Depending on your usage.

Or HPLC is going nearly 24/7, so I have to do this very often. It is the easiest way to spot trouble, and it sucks when they pumps go bad. We have to replace a part designed to ware down over time every 3-5 months, which is why we check so often.

[JGK]

Instead of pumping through the column, turn on the purge valve.
Set it at a flow rate, say 1mL/min, start the flow for a few second and make sure the pumps are at full speed. Get a timer and set it for 5 minutes. Start collecting the effluent into a good graduated cylinder, start the timer when you start collecting. In 5 minutes you should have 5 mL. Mark the level with a sharpe. Repeat the procedure. Does it come back up to the sharpe level the second time (within error)? Is it 5 mL within error?

If you have a dual pump system, do it with each pump individually.
And if you do a lot of gradients and work over different ranges, I would check it at different flow rates. IE. 0.5mL/min, 1mL/min, 2mL/min. Depending on your usage.

Or HPLC is going nearly 24/7, so I have to do this very often. It is the easiest way to spot trouble, and it sucks when they pumps go bad. We have to replace a part designed to ware down over time every 3-5 months, which is why we check so often.

Certain systems (Waters) can not be easily tested in this way. Also testing the flow  via the purge valve ( against a zero resistance) may not detect problems which may be seen if the pump is working as intended against a back-pressure.

Intall a column and use a set flow (1 mL /minute) and time the filling of a volumetric flask (10 mL?) and calculate the actual flow rate and compare the error vs the nominal rate. Test each channel and some combinations.

[enahs]

We have 2 Waters systems, and I do this method all the time.

You are correct about testing it with pressure building up too. But I have never found it to not work with the column in place and work fine going through the purge valve.

Or instead of purge valve, directly from the pump output.

[JGK]

We have 2 Waters systems, and I do this method all the time.

You are correct about testing it with pressure building up too. But I have never found it to not work with the column in place and work fine going through the purge valve.

Or instead of purge valve, directly from the pump output.

It may work well to test without a column in place, but it's like saying a car is fully working just by starting the engine. A test which does not mimic the system as it is intended to be used is not comprehensive and may not pick up deficiencies that may turn up when the pump is operated under pressure.

If you are determined to perform a test without a column I would suggest that you measure at the from the pump output but fit a back-pressure regulator (500 psi).

[freeze0912]

I get it~~
Check the pumping system by time~~
Will organic solvent(metanol, etc) better than water
Or it is not a matter of the mobile phase
The column of HPLC is C18

[freeze0912]

Instead of pumping through the column, turn on the purge valve.
Set it at a flow rate, say 1mL/min, start the flow for a few second and make sure the pumps are at full speed. Get a timer and set it for 5 minutes. Start collecting the effluent into a good graduated cylinder, start the timer when you start collecting. In 5 minutes you should have 5 mL. Mark the level with a sharpe. Repeat the procedure. Does it come back up to the sharpe level the second time (within error)? Is it 5 mL within error?

If you have a dual pump system, do it with each pump individually.
And if you do a lot of gradients and work over different ranges, I would check it at different flow rates. IE. 0.5mL/min, 1mL/min, 2mL/min. Depending on your usage.

Or HPLC is going nearly 24/7, so I have to do this very often. It is the easiest way to spot trouble, and it sucks when they pumps go bad. We have to replace a part designed to ware down over time every 3-5 months, which is why we check so often.

It is a good method but using a timer to record will increase the uncertainty
The error of reaction time is large

[enahs]

1 second difference compared to 5 minutes is not going to be significant.
It does not even have to be 100% correct. As long as it is consistent. But if it should be 5mL and you get 3mL, you have a problem. If it should be 5 and you get 4.95 or 5.05, you are fine.

Any solvent should be fine. As I said, we have many different kinds of HPLC's. It has always been pretty obvious when something is going wrong.
This is just a quick method that works reasonably well.