Direct Measurement of Chocolate Components Using Dispersive Raman Spectroscopy at 1000 nm Excitation

Chocolate is a popular food around the world. Making chocolate-based confectionaries involve multiple processing steps including cocoa bean fermentation, cocoa bean roasting, grinding, and then a controlled crystallization, where the processing conditions yields the desirable polymorph V to give chocolate its characteristic snap and texture. Raman spectroscopy is well known as a technique that can provide a non-contact, non-destructive analysis of chemical composition and molecular structure. Yet, excitation in the visible and near-infrared (532-785 nm) has not been possible for dark or milk chocolate because of the samples' overwhelming fluorescence. New technologies enabling Raman spectroscopy closer to shortwave infrared wavelengths, closer to 1000 nm, are likely to reduce fluorescence of chocolate and other highly fluorescent samples. Based on the successes of 1064 nm excitation to understand chocolate blooming, we hypothesized that 1000 nm excitation would also reduce fluorescence and enable Raman spectroscopy in dark and milk chocolates. We used dispersive Raman spectroscopy at 1000 nm to measure white, milk, and dark chocolate and cocoa nibs. The use of 1000 nm excitation effectively reduced fluorescence, enabling qualitative and quantitative Raman spectroscopy directly on chocolate samples. These feasibility studies indicate that 1000 nm Raman spectroscopy can be used to measure chocolate in a laboratory or process environment.

Raman spectroscopy as a process analytical technology for pharmaceutical manufacturing and bioprocessing

Adoption of Quality by Design (QbD) principles, regulatory support of QbD, process analytical technology (PAT), and continuous manufacturing are major factors effecting new approaches to pharmaceutical manufacturing and bioprocessing. In this review, we highlight new technology developments, data analysis models, and applications of Raman spectroscopy, which have expanded the scope of Raman spectroscopy as a process analytical technology. Emerging technologies such as transmission and enhanced reflection Raman, and new approaches to using available technologies, expand the scope of Raman spectroscopy in pharmaceutical manufacturing, and now Raman spectroscopy is successfully integrated into real-time release testing, continuous manufacturing, and statistical process control. Since the last major review of Raman as a pharmaceutical PAT in 2010, many new Raman applications in bioprocessing have emerged. Exciting reports of in situ Raman spectroscopy in bioprocesses complement a growing scientific field of biological and biomedical Raman spectroscopy. Raman spectroscopy has made a positive impact as a process analytical and control tool for pharmaceutical manufacturing and bioprocessing, with demonstrated scientific and financial benefits throughout a product’s lifecycle.

Off-line and on-line measurements of drug-loaded hot-melt extruded films using Raman spectroscopy

The objective of this study was to investigate the use of Raman spectroscopy for the quantitative and qualitative analysis of an active ingredient in hot-melt extruded film formulations. Clotrimazole and ketoprofen were used as the active pharmaceutical ingredients (APIs) in the subject formulations. Films were prepared with contents varying from 1 to 20% of the respective API. Raman spectroscopy was used to quantify these APIs, both off-line and on-line. The spectral data were also used to ascertain the physical status of these APIs in the formulations. For off-line analysis, the films were cut into small rectangles, and the amount of the API was measured using a fiber optic probe equipped with a non-contact optic (NCO). For on-line analysis, real-time measurements were accomplished by fixing the probe over the extruded film for continuous data collection. Raman spectroscopy can be a convenient alternative to HPLC and other techniques currently employed for the quantification of the API in these formulations. Because Raman is also sensitive to changes in crystallinity, employment of the technique provided additional information to deduce the crystalline status of the API. The results reported in this paper suggest the suitability of Raman for PAT applications because of the on-line capability.

Comparison of sampling techniques for in-line monitoring using Raman spectroscopy

Raman spectroscopy is currently of interest as a process monitoring tool for pharmaceutical unit operations. In this study, the performance characteristics of Raman spectrometers with different sampling optics have been investigated in the context of process monitoring, with emphasis being placed on assessing homogeneity in powder blends and following changes in solid-state form during wet granulation. A novel large spot non-contact Raman sampling device was compared with a traditional small spot size non-contact sampling device and an immersion probe. The large spot non-contact optics provided significant advantages over the standard systems both as a result of the enhanced sampling volume and because of the greater robustness of the system to fluctuations in the sampling distance during the wet granulation process.

Anti-Stokes Raman spectrometry with 1064-nm excitation: an effective instrumental approach for field detection of explosives

Anti-Stokes Raman spectra of 28 explosive materials were obtained with 1064-nm excitation using fiber-optic sampling and a dispersive spectrograph equipped with a charge-coupled device (CCD) array detector. By using a silicon CCD detector, anti-Stokes features could clearly be observed for the majority of samples from -250 to -1650 cm(-1). Using the fiber-optic probe, spectra were routinely obtained from samples positioned up to twelve meters from the spectrograph within 240 s. The utility of an anti-Stokes correction routine is demonstrated, which routine allowed anti-Stokes spectra measured with 1064-nm excitation to be successfully searched and identified against libraries of Stokes spectra obtained using a Fourier transform (FT) Raman system equipped with a 1064-nm Nd:YAG laser.