Confidence interval for single sample analysis

#21
Did you find a simple description about how to compute variance components? Try to do that.

What software are you using?

I think the best way to estimate the precision of the measurement would be to calculate the relative standard deviation, that is the standard deviation as a percentage of the mean for each compound.
I am sorry, but I don't agree. Why would that be a good (or even "the best") way?