The Influence of Measurement Parameters on the Specific Rotation of Amino Acids

Part II. The Effect of Sulfuric Acid Concentration to Specific Rotation

Abstract

A steep decrease in value of specific rotation was observed when concentration of sulfuric acid reached more than constant normality for each amino acid. Ultraviolet ab-sorption, nuclear magnetic resonance and Raman spectra showed that these decrease of specific rotation in concentrated sulfuric acid are attributed to the protonation of carboxyl group. The concentration of sulfuric acid in which amino acids showed maximum specific rotation are as follows.
Amino Acids Normality of sulfuric acids
L-Arginine 10 to 11
L-Aspartic acid 2 to 3
L-Isolcucine 20
L-Leucine 20
L-Phenylalanine 18
L-Valine 20