By shirish patel on Wednesday, April 18, 2001 - 11:21 pm:
if i am doing a impurity detection first i would have to find out the s/n ration . lets say it is y
but after 2 , 3 hours it suddenly changes to
the 5y . so can i continue with this probleam so i would have to again find out the s/n ratio and carry on the determination. this is always a probleam in impurity detection , as in routine
no body performs this , but for the stability
i mut have to find out the s/n so what is the
procedure i should follow that i can convence
fda persons.
By M Emerick on Thursday, April 19, 2001 - 10:39 am:
Typically one would inject low amounts of the main component and hope to get close to the detection and quantitation limit. To find out if the concentration was at the limit you would then look at the noise and get one that is three times and one at ten times.
Of course lamp energy along with other perameters would make this different from machine to machine. But, it would be impractical to run this everytime. If the quantitation limit is well below 0.01% of the main component FDA will be happy. All you are required to report are impurities greater than that amount. The fact that it fluctuates day to day is not an issue, unless you are right at the required detection for the impurities.
By Mike LEVI on Wednesday, April 25, 2001 - 11:01 am:
to M Emerick
R u sure that the limit for Fda relevant impurities is 0,01%. Isn't it 0,1%. That's what i've been told by my LabHead.
By M Emerick on Wednesday, April 25, 2001 - 02:01 pm:
I am corrected. It is 0.1% not 0.01%. We typically look for that here since we call anything 0.05% or more 0.1%. Therefore we want to be able to see that small of a percent.
Thank you Mike LEVI for bring out that correction.
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