l-Threonine

l-Threonine C₄H₉NO₃ = 119.1 (72-19-5)

Chromatographic reagent grade of commerce.

A white, crystalline powder; , about –28 (2% w/v in water).

Complies with the following test.

Homogeneity Carry out the method for thin-layer chromatography, Appendix III A, protected from light, using silica gel G as the coating substance and a mixture of 25 parts of water and 75 parts of phenol as the mobile phase but allowing the solvent front to ascend 12 cm from the line of application. Apply to the plate 5 µL of a 0.2% w/v solution of the reagent being examined and keep the plate in the vapour of the mobile phase for 12 hours before development. After removal of the plate, dry it, spray with a 0.1% w/v solution of ninhydrin in butan-1-ol saturated with water and heat at 100° to 105° for 10 minutes. The chromatogram shows only one spot.