With a UV-Vis spectrophotometer, I took the absorbance of standard solutions in triplicate over a certain concentration range and I obtained Absorbance values of ~0.1 to 0.5. I plotted concentration versus absorbance as per Lambert-Beer's law and obtained an equation for a straight line with R2 of >0.9. I also, however, acquired an intercept or constant of +0.218.
I struggled to find answers but according to my read through some of the literature and comments from colleagues, large intercepts such as the one I obtained can arise from instrumental variations but I am not entirely sure or convinced.
What could be the cause of a large intercept?