Chemical identity testing by remote-based dispersive Raman spectroscopy.

The advent of robust, rugged, and current Good Manufacturing Practices (cGMP) compliant hand-held Raman spectrometers provides a wealth of opportunities for the analytical pharmaceutical chemist to bring the laboratory to the sample. This paper discusses the use of hand-held Raman spectrometers for the development of qualitative chemical identification methods for a number of well-known pharmaceutical products (tablets and capsules). Methods were developed on two different instruments and transferred to a third instrument for application of the methodology to independently obtained drug products. A novel decision algorithm is presented for the assessment of the correlation between the Raman spectrum of the unknown sample to the spectrum of the authentic reference material. This novel algorithm considers accuracy but more importantly precision (uncertainty/reliability), thus removing human bias that is associated with typical spectral searching approaches. The results presented in this paper show the reliability of developing, validating, and transferring chemical identification assays on hand-held Raman spectrometers.

On pattern matching of X-ray powder diffraction data.

We introduce a novel pattern matching algorithm optimized for X-ray powder diffraction (XRPD) data and useful for data from other types of analytical techniques (e.g., Raman, IR). The algorithm is based on hierarchical clustering with a similarity metric that compares peak positions using the full peak profile. It includes heuristics developed from years of experience manually matching XRPD data, and preprocessing algorithms that reduce the effects of common problems associated with XRPD (e.g., preferred orientation and poor particle statistics). This algorithm can find immediate application in automated polymorph screening and salt selection, common tasks in the development of pharmaceuticals.

Solid-state nuclear magnetic resonance spectroscopy--pharmaceutical applications.

Solid-state nuclear magnetic resonance (NMR) spectroscopy has become an integral technique in the field of pharmaceutical sciences. This review focuses on the use of solid-state NMR techniques for the characterization of pharmaceutical solids (drug substance and dosage form). These techniques include methods for (1) studying structure and conformation, (2) analyzing molecular motions (relaxation and exchange spectroscopy), (3) assigning resonances (spectral editing and two-dimensional correlation spectroscopy), and (4) measuring internuclear distances.