Chromatography Forum

Hi Guys,

I am getting placebo peak at same time of my active peak. I am getting hard time to move it. Is there any calulation allowed if i substract placeo area? Does ICH or FDA allowing some % interference? Any thoughts????

I was hoping that someone with more direct experience would respond. In the absence of that, I'll give you my opinion:

Is there any calulation allowed if i substract placeo area?

No

Does ICH or FDA allowing some % interference?

No. The only exception that I can see would be if the placebo peak is at or below the limit of quantitation, and then you would have to do an extensive validation to demonstrate that any bias is not statistically significant (and then convince a reviewer!).

You either have to separate the peaks chromatographically or detect your analyte specifically (different wavelength? fluorescence? MS?).

Personally, I say there are only two cases:

(1) There is absolutely zero placebo contibution; of course, someone has to actually define what zero is. And zero really doesn't exist in our business, does it?

(2) There is a contribution; one must determine if such a contribution is significant.

So I agree (as usual) with Tom. For example, if a product contains 12.5% octyl methoxycinnamate sunscreen active, and a placebo or reagent blank would calculate as 0.001% (as OMC), then I'd say that is insignificant. Most likely one would need to use completely different integration events to even see such a tiny contribution in real life, wouldn't be so senstive for settings for real samples.

So I'd argue that the only real situation is (2).

Or you could try change wavelength, adjust method, ...
Are you absolute sure the contribution comes from you placebo, and isn't carryover, or a contaminated placebo?

Ace