2024 AIChE Annual Meeting

Solvent and Concentration Effects on Polymorphic Forms of Glutaric Acid

Glutaric acid, a five-carbon dicarboxylic acid, is known for its polymorphic properties, characterized by the ability to crystallize in multiple distinct forms. Polymorphism, the phenomenon where a single chemical compound can adopt different crystalline structures, plays a significant role in determining the physicochemical properties of substances. A notable example is carbon, which can manifest as either graphite or diamond. The polymorphic behavior of glutaric acid is particularly relevant in pharmaceutical applications, where the specific polymorph can profoundly impact a drug's bioavailability, stability, and therapeutic efficacy. Glutaric acid predominantly exhibits two polymorphs: the metastable alpha form and the stable beta form.

In this study, we investigated how using different solvents at varying concentrations affects the polymorphic outcome of glutaric acid. Particles of glutaric acid were generated by using an atomizer and dried using two different drying media: silica gel and zeolite when water was employed as the solvent, and charcoal and zeolite when alcohol was used. The resulting particles were collected on an X-ray diffraction (XRD) disk in a PIXE Cascade Impactor, with any residual particles being captured on a NeoPore filter. The collected samples were subsequently analyzed using powder X-ray diffraction (pXRD). Data analysis was performed using MATLAB and Excel to determine the polymorphic composition of the samples. The results show that the choice of solvent impacted the polymorph that was present, and that the water based experiments displayed polymorphism that isn’t found through other methods of water crystallization.