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Ninhydrin Coloring Solution Kit for HITACHI Technical Information
Ninhydrin Color Development Method
Ninhydrin reaction is a method to detect and quantify amino acids via ninhydrin coloration.
Amino acids reacted with ninhydrin reaction reagent are detected using two wavelengths, i.e., 570 nm and 440 nm.
The primary amine amino acid (α-amino acid) is colored purple at 570 nm, while the secondary amine (imino acid) amino acid is colored yellow at 440 nm.
Protocol
Methods for amino acid analysis include precolumn derivatization and postcolumn derivatization employed by ninhydrin. Postcolumn derivatization is a method in which a sample is reacted with the derivatization reagent after column separation and transferred to the detector.
Flow diagram of ninhydrin method1)
- Ito, M. et al. : Wako Jun-yaku Jiho, 86 (3), 15 (2018).
Measurement Principle
- The sample is pressured into an alkaline-cation exchange resin. When the eluent pH is increased in a stepwise manner, a higher amount of acidic amino acid is eluted early.
- When this eluate is heated after the addition of Ninhydrin Coloring Solution, a colored substance showing the local maximum absorption is produced at 570 nm for α-amino acid and 440 nm for imino acid.
- The peak area of this colored substance is compared with that of the standard solution to determine the concentration of each amino acid in the sample.
