Formulas and colorimetric tables for correct apparent deviations to Beer's law

Abstract

For the compared colorimetric determinations we propose the following- general formula, based on the Beer’s law:

(C+ I)E = (C’+ I) E’

in which C and C’ = concentrations; E and E’ = layer thickness, and I the algebraic sum of the constant impurities and losses that can be added or substracted to the intensity of the coloration evolved.

By means of this mathematical formula we are able to obtain the corresponding proportionality in many reactions that were deviated of the old insuficient expression C E = C’ E’.

It is described a simple procedure, based on the same mathematical formula, which permits to calculate I in function of the comparison of two standards.

We demonstrate his validity for the phosphor determinations, and also for the uric acid and creatinine, in un favorable conditions, and with differences of concentrations as far as the 20 to the 800 per cent.

We give the tabulations of the calculated numbers, in order to obtain directly the concentrations of the problems in the cases of the possible aplication of the method (when I is not equal to 0).