Instrumental LOQ or LOQ of the method?

[moonchips]

I am developing and validating a method.
As I know, people usually use 10 S/N instrumental LOQ. But there is no sample preparation factor consifered in this instrumental LOQ.

Shall I use Instrumental LOQ or LOQ of the method in my method development?

thanks

[tom jupille]

Actually, the s/n approach is only an estimate of LOQ. For that matter, the alternative (based on the standard error of the regression line) is also based on standards, so unless you run your standards through the sample prep procedure, the same issues would apply.

When you get right down to it, the only way to truly verify LOQ is to run spiked standards at that level and demonstrate that the precision is good enough for your purpose.