L-2-Amino-3-hydroxybutyric acid; L-Threonine, USP Grade; L-Threonine, allo-Free; H-Thr-OH; (2S,3R)-(-)-Threonine; Thr; (2S,3R)-2-Amino-3-hydroxybutyric acid~H-Thr-OH; 2-Amino-3-hydroxybutanoic acid; 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carbaldehyde semicarbazone