Spectroscopy-02-01-2017

Portable instrumentation for Raman spectroscopy has rapidly evolved over the last decade, where sample testing that once occurred in the laboratory is now executed in the field (e.g. warehouse).   Portable Raman spectroscopy is a powerful technique for the rapid identification of diversely sourced raw materials used in pharmaceutical processing.  In addition to portability; reduced cost, rapid data acquisition and ease of use make this powerful technique attractive and accessible to both expert spectroscopists and non-specialists.  In most cases, the method development can be easily accomplished in the laboratory after which the instrument and methods are transferred to field for sample analysis or warehouse areas for inspection of incoming raw material.  Qualitative Raman methods for identification of raw materials typically utilize spectral libraries for sample to standard comparison.  When developing Raman spectral libraries for raw material identification, great care is required when considering critical factors (e.g. instrument type, Raman capability, container type, container interference, background interference, material variability) that can potentially influence the identity of the material.  This paper discusses portable Raman techniques and approaches for raw material identification, as well as key considerations for developing and validating Raman spectral libraries.

Data governance requires a multi-layered approach that runs throughout a regulated organization from top to bottom.  Although data governance features in the majority of GxP data integrity guidance documents, the approach to the topic should be business-driven rather than regulatory-driven.

This article reviews the state-of-the-art of far-ultraviolet (FUV) spectroscopy of solid and liquid phases. FUV spectroscopy is rich in information about electronic structure and transitions of a molecule, but this region has been employed to investigate mainly for the electronic states and structure of gas molecules because the absorptivity is very high in the FUV region. To overcome this difficulty we have developed a totally new FUV spectrometer based on the attenuated total reflection (ATR) technique. ATR-FUV spectroscopy has paved a new avenue for condensed matter FUV spectroscopy. This article demonstrates that FUV holds considerable promise not only in basic science such as studies of electronic structure of molecules, hydrogen bonding, hydration, and adsorption of water and aqueous solutions, but also practical applications, such as on-line analysis, geochemical and environmental analyis, semiconductor research and surface analysis.

Controlling the orientation of the laser and Raman polarization relative to the sample orientation can provide a wealth of information in the Raman spectrum that would be difficult to achieve by other methods. Presentation of the spectra makes these effects appear straightforward, but because of multiple instrumental factors, and experimental design, it is easy to produce erroneous results. This column is going to explain what instrumental components affect the polarization effects that are observed, and how the sample setup itself affects the Raman signal.

As we have previously discussed, the most time consuming and bothersome issue associated with calibration modeling and the routine use of multivariate models for quantitative analysis in spectroscopy are the constant intercept (bias) or slope adjustments. These adjustments must be routinely performed for every product and each constituent model. For transfer and maintenance of multivariate calibrations this procedure must be continuously implemented to maintain calibration prediction accuracy over time. Sample composition, reference values, within and between instrument drift, and operator differences may be the cause of variation over time. When calibration transfer is attempted using instruments of somewhat different vintage or design type the problem is amplified. In this discussion of the problem we continue to delve into the issues causing prediction error, bias and slope changes for quantitative calibrations using spectroscopy.

Raman spectroscopy is one of the fastest growing segments of the molecular spectroscopy techniques.

Click the title above to open the Spectroscopy February 2017 regular issue, Vol 32 No 2, in an interactive PDF format.