My apologies for the delay in response. Our company had a visit from our regulatory agency this week. All went well, but it certainly redirected my focus for a few days.

AdarianF,
You are correct about my linearity. 0.999 was a typo on my part. You were also correct about lowering the concentration as well. By lowering the concentration to about 20% of the initial, the results improved nicely.

shaun78,
There were no sample prep errors that were apparent and sample weights were in the 20 mg range on a 5 place balance. I do agree with you about evaluating the method ahead of time but I don't always have that luxury.

Thanks again for everyone's input. You've been very helpful.

Jeff