Investigation of Thermodynamic and Morphological Properties of Crystalline 4-HPG (4-hydroxyphenylglycine) Using Raman, PXRD and DTA/TGA

This study focuses on the detailed physical characterization of 4-HPG, a significant impurity found in some of the most commonly prescribed β-lactam antibiotics worldwide. Various analytical techniques, including X-ray powder diffractometry, dynamic light scattering, scanning electron microscopy, Fourier-transform infrared, and Raman spectroscopy, were employed to characterize the properties of 4-HPG crystals. XRD analysis revealed the crystallinity and small crystallite sizes of 4-HPG particles, supported by DLS and SEM analyses. FT-IR and Raman spectroscopy results exhibited excellent agreement, providing insight into the structural characterization of 4-HPG. Thermal analysis revealed a two-stage degradation feature of 4-HPG. Overall, this study contributes to a better understanding of 4-HPG's structure and its impact on antibiotic stability.