LOQ necessary in validation?

[ms3072]

Hello everybody

We have this discussion in our lab about the necessity of the determination of the LOQ .
The problem is as follows:
We use a HPLC method for the determination of the tocopherol content in lipid samples. The method will have to be validated soon. The question is: Do we have to determine the LOQ because tocopherol is used as a stabilizer (impurity) in lipid samples OR can we leave the LOQ out because this HPLC method is an assay for the tocopherol content of the sample (we do not quantify other peaks in the chromatogram apart from tocopherol)?

Thanks a lot!

[Peter Apps]

The rationale behind determining an LOQ is to ensure that all reported results are above it. Although the LOQ is a property of the method, if you have, say, 1 % of a component you do not need to demonstrate that your method can get down to 1 ppm. Show that the method gives good repeatability / reproducibility / deviation from linearity or whatever at 0.5 % and you will have established suitability for purpose.

Peter

[DR]

Yes - just establish accuracy & linearity over a range that you could reasonably anticipate seeing in real samples (plus some). Say 50%-150% or 75%-125% of theory.

[ms3072]

Thank you very much for your help!