Clarity discussion forum

I have been asked to set up a calibration for a customers method, and they
have specified that each of six standards should be run six times.



When I set up the calibration, it automatically takes the average of the six
repeat runs for each standard level and displays that on the calibration
graph. The customer has asked to see the scatter of the points, and for
linear regression to be calculated for the regression coefficient. Is it
possible for the software to display each individual point, and to calculate
based upon each individual point instead of just the average point for each
level?



Best regards

Stuart


Dr Stuart Jones

============================================================

Laserchrom HPLC Laboratories Ltd - Everything for Successful HPLC

Unit B16-18, Laser Quay, Medway City Estate, Rochester, Kent, England ME2
4HU

Tel: +44 (0)1634-294001 FAX: +44 (0)1634-297533 Mobile: +44 (0)7973-428867

www.laserchrom.co.uk stuart@laserchrom.co.uk

Dear Stuart,

in such cases I usually recommend to set each replicate point as a separate level. The linear regression is made from all points and you can see the scatter of the points on the graph. In your case, unfortunately, the number of points (6 levels by 6 replicates = e36) exceeds the maximum number of 20 calibration levels available in Clarity. When using the average option, the replicate point values can be checked by the command Calibration/Show History from individual compound tabs in the Calibration window. Regarding the linear regression, the resulting calibration curve coefficients are the same when calculating from individual points or from averages. The correlation coefficient will of course differ as well as the residual sum of squares. I suppose such calibration will be done only occasionally for some method validation, thus I will suggest to export the data to MS Excel or other spreadsheet and calculate the regression coefficient there.

Best regards

Ivan Vins

DataApex