Spectroscopy measurements may be made in either percent transmittance (% T) or absorbance (A). Based on the mathematical relationship between absorbance and transmittance, A = - log T, explain why calibration curves of absorbance versus concentration may deviate from a straight line when A1.

According to Beer’s Law, A=Ebc, under ideal conditions, a substance’s concentration and its absorbance are directly proportional: a high-concentration solution absorbs more light, and solution of lower concentration absorbs less light. Since concentration and absorbance are proportional, Beer’s Law makes it possible to determine an unknown concentration of phosphate after determining the absorbance.