Letter | Published:

An Improved Biuret Reaction of Proteins and the Two-Standard Colorimetry

Nature volume 160, page 89 (19 July 1947) | Download Citation



Mehl announced in 19451 that by the use of ethylene glycol an alkaline copper reagent could be prepared in which copper, besides not being precipitated, could give the biuret reaction. At the high proportion in which glycol enters into Mehl's reagent, the presence of reducing impurities made it necessary to prepare the reagent in two stages, heating in order to speed up the reaction, and filtering in order to remove the precipitated copper. Nevertheless, the presence of the colour of the alkaline copper reagent causes the reaction to depart considerably from Beer's law; Mehl deduces from a spectrophotometric analysis that, starting from the 750 mµ and 545 mµ absorptions, the quantity of proteins present can be approximately calculated.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    , J. Biol. Chem., 157, 173 (1945).

  2. 2.

    , R. esp. Fisiol., 1, 355 (1945).

  3. 3.

    , An. Fis. Quim., 42, 855 (1946).

Download references

Author information


  1. Instituto de Fisiología, Facultad de Medicina, Barcelona. April 18.

    • A. SOLS


  1. Search for A. SOLS in:

About this article

Publication history




Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.