Noninvasive Identification of Materials inside USP Vials with Raman Spectroscopy and a Raman Spectral Library

Abstract

A commercial dispersive Raman spectrometer operating at 785 nm with a CCD detector was used to acquire spectra of USP reference materials inside amber USP vials. The laser and collection beams were directed through the bottom of the vials, resulting in a 60% loss of signal. The Raman shift was calibrated with a 4-acetamidophenol standard, and spectral response was corrected with a luminescent standard. After these corrections, the Raman spectra obtained inside the USP vial and on open powders differed by less than 5%. A spectral library of 309 reference materials was constructed, with spectral acquisition times ranging from 1 to 60 s. Of these, 8% had significant fluorescent background but observable Raman features, while 3% showed only fluorescence. A blind test of 26 unknowns revealed the accuracy of the library search to be 88-96%, depending on search algorithm, and 100% if operator discretion was permitted. The tolerance of the library search to degraded signal-to-noise ratio, resolution, and Raman shift accuracy were tested, and the search was very robust. The results demonstrate that Raman spectroscopy provides a rapid, noninvasive technique for compound identification.

Rapid Detection and Identification of Overdose Drugs in Saliva by Surface-Enhanced Raman Scattering Using Fused Gold Colloids

“…Even though this drug has the least unique SERS spectrum presented here, it is easily identified as the best match with an HQI score of 0.073, and hydrocodone, the next best match, has an HQI score of 0.734, clearly a mismatch (Table 2). The success of this method is very similar to a previous study of 309 pharmaceuticals by Raman spectroscopy [36]. …”

Raman spectroscopy of protein pharmaceuticals

“…A 785 nm line is preferred to reduce fluorescence background, and a shorter wavelength line at 633 or 532 nm is chosen for better instrument sensitivity with samples that have little fluorescence. The Raman microscope is particularly powerful for microanalysis and chemical mapping of materials in solid states 35. Raman microscopy is an essential technique for forensic analysis in the pharmaceutical industry in conjunction with FTIR‐microscopy 35.…”

Raman Spectroscopy

“…This was done in a controlled fashion by placing tissue atop the plaques to increase their "depth". (100). Although the amber glass greatly attenuates the signal, adequate spectra were obtained for determination of vial contents with 1-60-s integration.…”

“…Raman microscopy was employed by McCreery and coworkers to study defect sites on and adsorption to carbon electrodes (109). The glassy carbon (GC) or highly ordered pyrolytic graphite (HOPG) electrode was contained in a specially designed Teflon cell.…”