The Acree-Rosenheim reaction is a

chemical test In chemistry, a chemical test is a qualitative property, qualitative or Quantitative property, quantitative procedure designed to identify, quantify, or characterise a chemical compound or substituent, chemical group. Purposes Chemical testing m ...

used for detecting the presence of

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...

in proteins. A protein mixture is mixed with

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

. Concentrated

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

is added to form two layers. A purple ring appears between the two layers if the test is positive for tryptophan. The test was named after two greats in

biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...

, namely, Solomon Farley Acree (1875–1957), a distinguished American Biochemist at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...

and Sigmund Otto Rosenheim (1871–1955), an Anglo-German Medical Chemist at the

University of Manchester , mottoeng = Knowledge, Wisdom, Humanity , established = 2004 – University of Manchester Predecessor institutions: 1956 – UMIST (as university college; university 1994) 1904 – Victoria University of Manchester 1880 – Victoria Univer ...

Reaction

The reaction of tryptophan with formaldehyde. Acree-Rosenheim reaction

References

Protein methods Chemical tests {{analytical-chemistry-stub