Nuclear Quadrupole Resonance Spectroscopy in Pharmaceuticals

Abstract

Nuclear quadrupole resonance spectroscopy (NQR) is a radio frequency–based technique applied to quadrupolar nuclei (spin I ≥ 1) which can be used to extract key information on the structure of pharmaceutical solids. NQR has the benefits of ease of data interpretation, applicability to crystalline and amorphous samples, and offering information on subtle interactions occurring in the structure. Despite its low sensitivity, 14N NQR has found applications in the field of pharmaceuticals to investigate polymorphism, tablet compaction, counterfeits, and crystal structures. In this chapter, we highlight the latest developments in NQR spectroscopy, with an emphasis on its applications to pharmaceutical research.