3 replies to this topic

[Hartwa]

I am trying to wrap my head around this problem.

 

We use 3M protein swabs to verify that tanks, valves, pumps are clean of proteins after running a cleaning cycle.  3M states that the detection limit is 50ug on the surface tested.

 

If I have a model where ....

 

Stream 1 is water at 830 lb/min

Stream 2 is a potential leak  (lb/min) that has 15% proteins 85% water

 

The product stream (P) is S1 + S2 with a concentration of what ??? for proteins?

 

My thought is that.....

 

50ug = 3.3E-8 lbs    so.... from the protein balance 0.15 * S2 = 3.3E-8 so S2 = 2.2E-7 lb/min

 

The problem is that is this is an almost 0 leak.  I am trying to find the minimum leak we could detect with this and that does not seem reasonable.

 

The swab is collected on a dry surface after the clean is complete and the lines drained....if we have 50ug on the surface we had that concentration in the P stream everywhere in that pipe.  Does that reasoning hold?  Am I thinking about that incorrectly?

 

I appreciate any thoughts.

[breizh]

Hi,

My experience in cleaning validation for Aspirin and Paracetamol productions is to measure the contaminant over a period of time until you reach the target before you decide to stop the cleaning process. Of course, the procedure and the results must be documented according to standard, let say GMP

To me, your swab test is just a one-point test, at the location or surface tested.  

About your calculation it's also weird to me, you mix mass flow and mass in your equation for protein.

note: 50ug or 50 micro gram =50e-06 g, should not be 1.10e-07 lb?

My 2 cents

Breizh

[Hartwa]

Thanks for the response.  All my streams are in lbs so converted 50ug to lbs.

 

What I am trying to do is determine the size of the leak that could be capable of triggering a failure if the protein swab is capable of detecting 50ug on the surface.  The real question I am asking is whether I am thinking about this correctly.

 

If 3M said that the lower threshold was 50ug/L or another concentration then no problem.  Since it is just a mass I am having trouble thinking about what concentration that would be.

[breizh]

Hi,

Attached similar test (most sensitive 3 micrograms) with description of the method included:

https://www.3m.com.e...p/d/v000078718/

 

To me the test is a black and white type, purely qualitative, meaning reaction to the test is a confirmation to be above the threshold. 

If you take a liter of solution (homogeneous) and you apply the test, it will tell you whether your contaminant is above 50 micrograms per liter.

 

Breizh