The infrared spectrums for 33 sorts of amino acid products were analyzed. The infrared spectrums of serine, aspartic acid, lysine acetate, glutamic acid(white crystallized powder), threonine, valine, alanine, leucine, proline, histidine monohydrochloric acid, arginine monohydrochloric acid, tyrosine and cystine were the same as the standard, but methionine, lysine monohydrohloric acid, glycine, glutamic acid (white crystal) differed from the standard. The difference may result from the different crystal for...