Recovery on PVC and Silicon Rubber

I tried different swabbing material conbined with different swabbing solvent for Fenofibrate. But the recovery for PVC and SR surface still very low (<10%). Any suggestions for this issue. Thank you in advance for you reply.

HI Dear,

How about recovery in Rinse sample? If it is good you can go ahead with rinse sampling itself. Recovery for swab samples on these surfaces is always a problem.

Satish Dange.

Thank you for your reply.
I try used 50ml of methanol to rinse a 10x10cm² coupon, The recovery still less than 10%. Note: Fenofibrate is practically insoluble in water, slightly soluble in methanol.
Any other suggesions!

Have you tried with acid / alkali solutions or soap solutions.
If you get good solubility & recovery in these, you can the same & after cleaning ensure the absence of these.

Satish Dange

Dear Bob

The recovery in silicon or PVC always is a problem, you must to investgated about the solubility… In my case had to recover Methotrexate swabbing using mobile phase described in the USP 32 but with this solvent recovered nothing, but suggested I review the solubility and mentioned that this was insoluble in ether and organics. But it also mentions that it is soluble in alkalis and alkali carbonates.
We had success with 0.1 N NaOH

Sorry my English is terrible …! But I hope my experience will serve you.

Thank you so much for kindly help. But the problem still remained there.
I tried use different swabing materials :Taxwipe and Gauze. Different swabing solvent, methanol, IPA, 10% to 90% methanol in water, tried 1%Acetic acid in methanol. The recovery is still less than 10%. I also used 50ml of methanol or 1% Acetic acid in methanol to rinse. the recovery is less than 10%.
It seems like the problem is Fenofibrate Molecule is sinked into the surface (or bind on it), and is not albe to remove from it.
Note: I used 1ml pipette to spike fenofibrate std ( in methanol )on the coupon,air dried. Could it be inproved by other method?
Guru and Expert please help.