BLANK PEAKS IN CALCULATIONS

[rc_12321]

I have a doubt about blank interferences.Can we directly subtract the area of blank peaks if known/unknown peaks are eluting at the same rt of blank peaks.I generally prefers injecting blank three times for consistancy in blank peaks and then the average of the three blanks is used in clculations.Is there any approach that best solve the problem?

[ntruong]

I do experience the similar situation where I have to subtract the blank because of the unknown in blank coelutes with one of the impurities in our product. Your approach is acceptable since the FDA investigators have no issue with ours. If your test method is already validated, you are stuck. Otherwise, I would work on another mobile phase system to pull the unknown peak (present in the blank) away from the peak of interest. I had no choice in my case since the test method was developed and validated by the contract lab.
Regards,

[syx]

what is this 'blank'? Sample matrix or diluent that is different with (initial) mobile phase?
If it is, it means that the method is not specific and need more adjustment. If it is gradient run without injection, one may need to purify the water or buffer component of the mobile phase.