Hi Smartin,
It was the LC-GC North America Pittcon 2004 issue, Vol. 27, No. 2, February. That was the issue that held the Dolan discussion of weighted linear least squares regression and how to analyze calibration data to determine if that fitting is appropriate.
A reference within the July 2009 LC-GC North America, also by Dolan, may be helpful
http://www.chromatographyonline.com/lcg ... ?id=613591as well as,
A.M. Almeida, M.M. Castel-Branco, and A.C. Falcão, J. Chromatogr., B 774, 215–222 (2002).
This also may be useful:
http://www.stat.cmu.edu/~cshalizi/350/l ... ure-18.pdfThe answer to your other main question is...maybe both the method as well as the fitting of the calibration data need to be carefully looked at. The main trouble I've had in my past with calibrations was in making an unfounded assumption that there was an absence of a "matrix effect" in the calibration standards. Generally a placebo or matrix matched to the samples...and occasionally treatment of the calibration standards as samples (like treatment) helped to repair poor correlation between calibration curve and sample data, whatever the data model that ended up as the chosen one.
Some detectors do "like", or seem to "like", polynomial fitting of data as opposed to straight line(s), weighted or not, but these are exceptions...often narrowing the range of the calibration can "cure" this.
I hope this helps a bit, and best wishes.