Hi Again, mengraul7,
Okay...the linearity of the Accuracy samples as preservatives + placebo (as well as the finished product?) seems to be well (R^2 ~ 1.000), check.
Also, a plot of analytical response vs. concentration (or amount) of each preservative affords a nearly horizontal line, check.
You successfully established the specificity of the preservatives in a spiked matrix (and the finished product?) and Diluent, check. How many different sources of placebo +matrix were evaluated (normally I've seen five independent preparations for these)?
I'm afraid I'm missing something, to me all looks well as per Huber:
https://www.agilent.com/cs/library/prim ... 5140EN.pdfAre the Accuracy values you report as the 50% and 150% levels in matrix vs. for each preservative in clean solvent?
I think the instrument(s) is/are fine based on what you've done...next would be to consider how the spiked matrix samples were prepared.