Effect of Particle Properties of Powders on the Generation and Transmission of Raman Scattering

Abstract

This version is available at https://strathprints.strath.ac.uk/40538/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. AbstractTransmission Raman measurements of a 1 mm thick sulphur-containing disc were made at different positions as it was moved through 4 mm of aspirin (150 -212 µm) or microcrystalline cellulose (Avicel) of different size ranges (<38, 53 -106 and 150 -212 µm). The transmission Raman intensity of the sulphur inter-layer at 218 cm -1 was lower when the disc was placed at the top or bottom of the powder bed, compared to positions within the bed and the difference between the sulphur intensity at the outer and inner positions increased with Avicel particle size. Also, the positional intensity difference was smaller for needle-shaped aspirin than for granular Avicel of the same size. The attenuation coefficients for the propagation of the exciting laser and transmitted Raman photons through the individual powders were the same, but decreased as the particle size of Avicel increased; also, the attenuation coefficients for propagation through 150 -212 µm aspirin were almost half of those through similar sized Avicel particles. The study has demonstrated that particulate size and type affect transmitted Raman intensities and consequently, such factors need to be considered in the analysis of powders especially if particle properties vary between the samples.2

Comparison of the Determination of a Low-Concentration Active Ingredient in Pharmaceutical Tablets by Backscatter and Transmission Raman Spectrometry

“…20,22,24,[29][30][31][32] The absence of sub-sampling limitations in transmission Raman spectroscopy has been illustrated by numerical simulations 20 and experimental investigations. 20,[33][34][35][36] Matousek and Parker showed that when a 0.5 mm thick inter-layer was moved from the sample surface to a depth of 3 mm within a tablet medium, the simulated backscatter Raman signal decreased by four orders of magnitude. 20 In comparison, numerical 20,34 and experimental [34][35][36] investigations showed that the signal was only weakly dependent on the depth of the inter-layer in transmission mode; a reduction in signal was observed when the inter-layer was located at the sample surface owing to loss of laser and Raman photons at the air-sample interface.…”

Variation in the Transmission Near-Infrared Signal with Depth in Turbid Media

“…[22][23][24][25][26] The lower NIR absorbance and Raman intensity observed for the interlayer when positioned at the surface can in both cases be attributed to lower photon density at the air-sample interface, relative to the center of the sample, owing to loss of photons to the air. This results in a reduction in the number of photons absorbed or Raman photons generated and subsequently detected when the interlayer occupies a nearsurface position.…”

“…In comparison, owing to the recent interest in the use of transmission Raman spectrometry for the analysis of pharmaceutical dosage forms, 20,21 there have been a number of theoretical and experimental studies examining the variation of the transmission Raman signal with depth in turbid media. [22][23][24][25][26] It was suggested in a recent paper that the variation in the transmission Raman signal with depth would also be exhibited by transmission NIR spectrometry. 22 While transmission Raman spectrometry can be employed with non-absorbing and weak to moderately absorbing materials, 22 it is inherent to NIR spectrometry that at least weakly absorbing materials are present to give rise to a signal.…”

“…17 These observations are also consistent with those noted for the Raman signal from an interlayer containing TiO 2 as it was moved through a stack of the eight Avicel disks. 22 In previous Raman studies, [22][23][24][25][26] the lower Raman signal observed when the interlayer occupied a surface position was attributed to loss of photons to the air at the air-sample interface. This results in a reduction in the number of Raman photons generated and subsequently detected when the interlayer occupies a near-surface position.…”

Quantitative Analysis of Pharmaceutical Bilayer Tablets Using Transmission Raman Spectroscopy

“…However, the orientation did not significantly affect the BMS-B data set with the ratio of the two measurements being approximately 1 for all the tablets. Townshend et al [16] also performed TRS measurements while flipping the tablets; however, rather than directly comparing the Raman intensity, they studied the photon attenuation coefficient as a function of tablet thickness and determined that attenuation coefficient was not impacted by tablet orientation. In our study, since the ratio of the signals was significantly different for the two materials (BMS-A vs BMS-B), then the tablet orientation should be controlled during analysis.…”