
 Posts: 4
 Joined: Tue Jul 10, 2018 6:33 pm
I'm able to replicate the equation that ChemStation generates (that is, the y = ax^2 + bx + c, as well r), by using the Excel array formula
=LINEST([peak area],[curve point concentrations]^{1,2},TRUE,TRUE)
to generate a, b, and c. This LINEST function gives me the exct a, b, and c that Chemstation spits out in the calibration report.
However, when I then try to use a, b, and c to determine the concentrations of my sample, I get results that are wildly, WILDLY out of line with what ChemStation calculates. (The Excel formula I'm using is
=(a * ([area]^2) ) + (b * [area]) + (c)
where a, b, and c are derived from the LINEST function above). But, if I change the LINEST function, and swap the x and y to
=LINEST([curve point concentrations],[peak are]^{1,2},TRUE,TRUE)
I get very different a, b, anmd c, but back caluclating for sampel concentrations I get very, very close to what ChemStation calculates...but not exact. Even using all 14 available decimals, my calculations vary from what ChemStation calculates.
Does anyone have any insight that they could share?