Question

What is the appropriate equation for determining the standard deviation of an analytical result from a calibration curve? Define all symbols used.

Answer 1

answer) during a method of validation it is  necessary to determine the limit of detection point (LOD) and the limit of quantification(LQD). this can be done by using calibration curve procedure.

the LOD= 3.3* /S

then the approximate equation for the standard deviation is given by;

=S/3.3*LOD

here,   =standard deviation S=slope of the calibration curve

LOD= limit of detection( it is the lowest quantity of a substance can be distinguished from absence of that substance with a stated confidence level.)

the standard deviation can be determined by calibration curve. a specific calibration curve should be studied using sample with analyte in range of LOD. the standard deviation of the y-intercept of regression line may be used as standard deviation.

a regression line y=mx+c based on this least square method given below. there is an inherent standard deviation also called standard error visualized look like this. we can calculate y-intercept of LOD using formula; yLOD=3.3+C and the LOD concentration (x) as ; x=3.3/m. this graph shown above.