Determination of 2-Methyl-4-amino-5-aminomethylpyrimidine

Abstract

2-Methyl-4-amino-5-aminomethylpyrimidine, possessing a -CH₂NH₂ grouping, reacts with ninhydrin to form Ruhemann purple. Pifer and others utilized this reaction in the colorimetric determination of this compound. The writers examined this method and devised a method with increased accuracy by modifying the conditions, such as the use of a brown-colored vessel to remove the effect of light and use of a buffer solution of pH 4 to make the pH of the test solution constant. In this modified method, the test solution is reacted with 1% ninhydrin, in the presence of pyridine, by warming in a boiling water bath for 30 minutes and the violet solution thereby formed is submitted to colorimetry at 570 mμ. The presence of 2-methyl-4-amino-5-acetamidomethylpyrimidine, sodium acetate, and sodium chloride does not interfere in this determination. Ammonia or ammonium ion does affect the determined value but they can be removed by low-pressure treatment. The accuracy of this method is within ±2%.