Chromatography Forum

Dear Friends

Any one has an idea about adjusting the flow rate on knauer HPLC pump s1000. I checked the flow rate with methanol/water 80:20 for 10 min at 1 ml/min and the volume in the cylinder was 10.4 ml. Somebody please guide me about the detail procedure to adjust the flow rate on knauer s1000 pump. I will be thankful.

afzal123_ahmed@yahoo.com

The S1000 manual is available for download here http://www.knauer.net/e/e_index.html?cf ... p&ptype=M'

From pg. 13 of the manual http://www.knauer.net/dwnld_fls/m_eg_pu_pump_s1000.pdf :

FLOW: You can enter a correction constant for the selected flow rate in a preset range [4000 - 6000].
This correction changes the number of pump cycles at a selected flow rate. This option allows for
compensation of the flow rate when using solvents with differing compressibility.

Only trained users should change this setting! (emphasis from the manual).

I checked the flow rate with methanol/water 80:20 for 10 min at 1 ml/min and the volume in the cylinder was 10.4 ml. Somebody please guide me about the detail procedure to adjust the flow rate on knauer s1000 pump.

So you set it for 1.00 ml/min and it delivers 1.04ml/min. So why is this bad, as long as it is consistent? How would it help you if it really could deliver 1.0000000ml/min?

Like if your autosampler or loop delivers 5.2ul injection instad of 5.00000ul, again who cares if it's consistent?

Some may ask if the cylinder was calibrated, what was the temperature, how many times did you measure, etc.

I checked the flow rate with methanol/water 80:20 for 10 min at 1 ml/min and the volume in the cylinder was 10.4 ml. Somebody please guide me about the detail procedure to adjust the flow rate on knauer s1000 pump.

So you set it for 1.00 ml/min and it delivers 1.04ml/min. So why is this bad, as long as it is consistent? How would it help you if it really could deliver 1.0000000ml/min?

Like if your autosampler or loop delivers 5.2ul injection instad of 5.00000ul, again who cares if it's consistent?

Some may ask if the cylinder was calibrated, what was the temperature, how many times did you measure, etc.

Dear Friend
Actually I am running a binary gradient and not having desired retention time. The deviation in flow rate is about 4 %, don't you think it is the cause of the problem.

Two purely measurement points spring to mind, one of them following afzal1's post.

The (in)accuracy on measuring cylinders is typically a few %, so you do not yet have strong evidence that the pump is not delivering 10 ml/min. If you want accurate measurements of the quantities of liquids you need to weight them (and then if you are interested in volume, calculate using the density at the temperature).

Also; if you mix 8 ml of water with 2 ml of methanol you do not get 10 ml, so if you want to measure pump performance you need to be pumping a pure liquid, or a premixed mixture - in other words do not use the pump to do the mixing.

Retention shifts in gradient methods are far more likely to be due to deviant ratios than to errors in total flow, so you need to check each channel independently at the flow rates required to generate the mixtures you need.

Peter

Dear Friend
I think channel 1 is delivering more liquid at 1 ml/min than the others, Does it mean that the solenoid valve of this channel is faulty? And do you think this is reason for the change in retention time or any other possibility?

If you have the wrong flow on any of the channels it will affect retention times.

Peter