Detection and quantitative determination of glycine with pyridine and p-nitrobenzoyl chloride.

SPECIFICITY 111 a qualitative test for glycine based on the color developed with pyridine and alkyl chloroformate was recently reported by Sublett and Jewell (13). Except for acetyl glycine and glycine hydrochloride, other amino acids and some other organic structures did not react in their method. In our investigations of the reaction specificity for glycine, it was confirmed that, except for hippuric and salicyluric acids, which are indistinguishable from glycine at lower sensitivity levels, a variety of organic structures did not develop colors. However, except for specificity, the quantitative glycine test is lacking in the other requirements that are essential for a reliable quantitative reaction. Interpretable colors were not obtained with less than 50 g. of glycine, although the detectable limit was reported as 1-2 .tg. Even at higher glycine concentration, the yellow color for the pyridine-ethyl chloroformate reaction is readily masked by the yellow color of protein hydrolysates and is obscured by urinary chromogens. With 100mg. concentrations, the effervescence of the reaction within the white precipitate produced by the reagents alone disperses and dilutes the