アラントインの安定性とその分解生成物の同定

抄録

The stability of allantoin was studied in pH 3.0, 6.0, and 8.0 buffer solutions at 50°C for 55 d. Allantoin was determined by high performance liquid chromatography (HPLC) with a cation exchange mode and colorimetry. The known degradation compounds, allantoic acid and glyoxylic acid, were simultaneously determined by ion chromatography. Urea was determined by HPLC with an ion pair mode. In the stability studies on pH 6.0 and 8.0 solutions, new degradation compounds of allantoin were identified as two growing unknown peaks in the HPLC chromatogram. Isolation of these compounds by preparative HPLC and ¹H, ¹⁵N and ¹⁸C-NMR spectra revealed that they were condensates of allantoin and glyoxylic acid, which also reacted positively in phenylhydrazine colorimetry. The amounts of these compounds were calculated from the determination results of other allantoin related compounds in the buffer solutions and were estimated as the biggest amount among all other compound. As they were found to be stable in an alkaline solution, conditions for hydrolysis in the colorimetric determination of allantoin were further examined. It was found that the longer hydrolysis gave more than 90% recovery in the colorimetry.