OQ/PQ of the pump: proportioning ripple

[LCFan]

Hello,

the European Directorate for the Quality of Medicines & HealthCare (EDQM) describes in the guideline PA/PH/OMCL (11) 04 (Qualification of Equipment) the periodic OQ/PQ of HPLC instruments.

For the part "pump", the testing of the proportioning ripple is described as follows:

The ripple of the gradient composition is the percentage of noise of the 50% line from the gradient program.

%R = 100*N/h50

%R ............ ripple
h50 ............. height of the 50% line
N ............... height of the noise line, measured during 1 minute in the linear region.

Limits: ≤ 0.2 %

The test is performed together with the gradient composition test, where the step with the 50%A/50% B composition is kept for 10 minutes.

What is the sense of this test an how is the limit justified?

Thank you very much for your help.

Regards

Florian

[HPLCaddict]

I'd say the sense of this test is to control the ripple (aka noise) introduced by incomplete eluent mixing and/or pump pulsations.
As for the limit...

[LCFan]

Hello HPLCaddict,

thanks for your reply.

I think, you are right with your assumption that it might be the "noise" test.

As the units of the Y-axis are not 100% comparable between all instruments, I assume that the limit is outlined in relation to the 50% gradient level. Might this be correct?

Regards

Florian