
 Posts: 2
 Joined: Tue Jul 10, 2018 6:33 pm
Because of the way my company has ChemStation set up, it is a tedious and slow process to use ChemStation to perform calculations against the quadratic calibration curve. I would much rather export my data to Excel, and run the numbers there, but I'm not quite able to replicate ChemStation's results.
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?
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?