However, this reagent does not only measure total phenols and will react with any reducing substance. The reagent therefore measures the total reducing capacity of a sample, not just the level of phenolic compounds. This reagent forms part of the Lowry protein assay and will also react with some nitrogen-containing compounds such as hydroxylamine and guanidine.
This reagent should not be confused with Folin's reagent, which is used to detect amines and sulfur-containing compounds.
A 1951 paper entitled "Protein measurement with the Folin phenol reagent" was the most cited paper in the 1945-1988 Science Citation Index, with 187,652 citations