Do i have to revalidate the method using some blank matrix or this matrix effect is acceptable?
I performed matrix base calibration(linearity) for validation.
All the parameters are well within acceptable limits.
I am just not so sure about matrix effect
Please guide.
Hello,
To validate a method, you have to demonstrate that your blank is really blank (no compound detected).
You have to find a real blank matrix that is not contaminated or in case this is not possible use other methods of quantification as standard addition.
Regards,
Andreu
Dear Ankita Sood are you referring to the Limit of Detection as LoD? Did you use the matrix you indicated for the validation as a 'blank matrix'? In that case, you can rest assured that no analytical data should be reported beneath the detection limit. The higher LoD may result from the matrix you employed for the evaluation. Is there a matrix with a lower blank value? Is matrix-adjusted calibration the best option? What was the motive for opting for this matrix over another? Standard addition may be a preferable choice in such situations. It may require increased exertion, which some may not be eager to do.
Dear Detlef Jensen
Thank you for your reply.
My LOQ (Limit of Quantification) is 50 ppb.
Yes, i used the indicated matrix as a blank matrix.
I have checked that validation data is not below LOD (Limit of detection)(20 ppb)
Matrix with a lower blank value is possible but I have to run multiple blanks samples to found one.
Matrix adjusted calibration was best as i was getting higher recoveries in aqueous calibration
Standard addition method i have not thought of yet.
Do i have to revalidate entire method with new blank i.e. actual blank?
What do you suggest?
Please share your expert advice
Regards,
Ankita
Dear Andreu Fabregat Rossell
Thank you for your reply.
I will definitely look for another matrix blank and seems i have to revalidate the entire method.
Regards,
Ankita
Dear Ankita Sood I am afraid you must return to the planning board. If you know there is a matrix with a lower blank value; there is no excuse for not using it. Using a blank matrix with significant contamination will raise questions regarding the method's validity and negatively impact LoD, LoQ, and likely the other analytical figures of merit. And please consider standard addition as an alternative. You might want to include it in your method validation to compare analytical results.
My two cents. Cheers Detlef.
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