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MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Biuret reagent test for protein. Add the blue Biuret solution to test tubes of protein solution at concentrations 0.0 0.1, 0.4, 2 and 10 mg/dm3. The strength of colour indicates the amount of protein present. The Biuret reagent is made of sodium hydroxide with hydrated copper(II) sulfate and potassium sodium tartrate is added to stabilize the cupric ions. It indicates peptide bonds when copper (II) ions in alkaline solution form a violet coordination complex. The protein in this case is was egg white.
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