Investigation on Raman spectral features of a coated tablet under variation of its orientation respective to laser illumination and measurement of nominal coating thickness of packed tablets.
To investigate Raman spectral features of a coated biconvex tablet under variation of its orientation respective to laser illumination, spectra of the tablet were collected by illuminating laser on 12 different locations on the tablet with 3 different illumination angles of 45, 75 and 90°. The spectral variations were more substantial when the tablet faces with engraved letters and greater surface curvature were measured, since the sampled volume of coating relative to that of a core tablet changed significantly under these circumstances as the illumination angle varied. The preliminary examination confirmed that the acquisition of tablet-representative spectra was the requisite for reliable measurement of coating thickness. Then, to mimic real monitoring of coating process, Raman spectra were directly collected on a packing of 30 tablets with repetition of random tablet packing up to 15 times and univariate models utilizing the intensity of coating peak at 638cm-1were developed using the cumulatively averaged spectra with an average weight of the 30 tablets as a reference. To acquire less tablet orientation-sensitive spectra, a wide area illumination (WAI) scheme providing a large sampling area (28.3mm2) on a tablet with a long focal length (∼25cm) was employed. The averaging of the first to seventh spectra, equivalently utilizing more packing-representative spectra for quantitative analysis, made the measurement of nominal coating thickness of packed tablets accurate.
Quality Management, Chong Kun Dang Pharm., Chungcheongnam-do, 330-831, Republic of Korea.
Jaejin
J
Kim
Department of Chemistry and Research Institute for Convergence of Basic Sciences, College of Natural Sciences, Hanyang University, Seoul, 133-791, Republic of Korea.
Jinyoung
J
Hwang
Quality Management, Chong Kun Dang Pharm., Chungcheongnam-do, 330-831, Republic of Korea. Electronic address: wooy@ckdpharm.com.
Young-Ah
YA
Woo
Department of Chemistry and Research Institute for Convergence of Basic Sciences, College of Natural Sciences, Hanyang University, Seoul, 133-791, Republic of Korea. Electronic address: hoeil@hanyang.ac.kr.
Hoeil
H
Chung
D007834:Lasers; D008029:Lighting; D013059:Spectrum Analysis, Raman; D013608:Tablets, Enteric-Coated; D013678:Technology, Pharmaceutical / Q000379:methods*
D013608:Tablets, Enteric-Coated
Nominal coating thickness; Packing-representative spectra; Raman spectroscopy; Tablet coating monitoring; Tablet orientation change