Is it possible to create a custom field which calculates the percentage difference between two areas over 2 injections. I have a sample with Component X. Injected twice after run for verification. Injection# 1 Area = 20000 Injection# 2 Area = 21000. The actual formula is (difference between peak area)/0.5(sum of peak areas) X 100, but how do I do this in a custom field and can it be reported on my report method?

Any ideas?