Why is the Folin phenol reagent preferred for protein measurement over other reagents?

The Folin phenol reagent is favored because it reacts with the aromatic rings and certain amino acids in proteins, forming a blue color that can be measured accurately with a spectrophotometer. This reaction is very sensitive and produces a strong, linear response over a wide range of protein concentrations, unlike some reagents that give weak or non‑linear signals. It is also tolerant of many common contaminants such as salts, reducing agents, and detergents, so it can be used directly on complex samples. The reagent requires only a small sample volume and a short incubation time, making it convenient for routine laboratory work. For example, when measuring bovine serum albumin, the Folin reagent gives a clear blue color that can be quantified accurately, whereas other reagents might give a faint or inconsistent color.