|Choquette, Steven Joseph
With the development of holographic notch filters, charge-coupled-device array cameras, and less expensive and more reliable lasers, Raman spectroscopy has become a viable analytical technique outside the research laboratory. Because the technique is rapid, nondestructive, and can yield both qualitative and quantitative information about a sample, it is becoming more frequently used in quality control and quality assurance applications. Such applications, common in regulated chemical and pharmaceutical industries, require that analytical methods employed be both verified and validated. Since Raman is an emission process, the appearance of a Raman spectrum is highly dependent on individual instrument characteristics such as line shape, excitation source, and detector response. Such dependencies have hindered the development of standard Raman spectral libraries. The lack of such spectral data bases, which have become so important for other spectroscopic techniques, has been problematic in validating Raman-based analytical methods. We are currently developing both wavelength (Raman shift) and intensity standards to normalize the response functions of Raman spectrometers. We hope that this will permit Raman spectra to be normalized and facilitate the creation of standard, instrument-independent Raman spectral libraries. In addition, we are working closely with consensus standards organizations and instrument manufacturers to develop standard methods to normalize Raman spectra and to develop appropriate Raman imaging standards.