Thermal stability of folic acid

This study attempts to identify the degradative process which folic acid undergoes under thermal stress. In order to facilitate the process, the various pieces of the chemical structure, namely, p-amino benzoic acid (PABA), pterin and glutamic acid as both its d- and l-isomers were investigated as separate entities. These structured pieces were then compared to the composite folic acid degradative thermogram in order to identify the peaks seen and provide direction for the interpolation of the degradative mechanism [Thermal stability of folic acid and associated excipients, M.Sc. thesis, 2001]. It was observed that none of the structural pieces could be superimposed as assumed earlier, and hence, an attempt was made to identify the decomposition products using various analytical techniques such as infrared (IR) spectroscopy, mass spectroscopy (MS) and X-ray diffraction (XRD) which suggested that the glutamic acid fragment is lost first as evidenced by acid loss and amide enhancement in the IR spectra. The vitamin was ultimately degraded to carbon fragments and that further identification was not necessary.