Simple transmission Raman measurements using a single multivariate model for analysis of pharmaceutical samples contained in capsules of different colors

• Published in: Talanta (Oxford) 2012-01, Vol.89, p.109-116
• Main Authors: Lee, Yeojin, Kim, Jaejin, Lee, Sanguk, Woo, Young-Ah, Chung, Hoeil
• Format: Article
• Language: English
• Subjects: Ambroxol; Ambroxol - analysis; Analytical chemistry; Calibration; Capsule color; Capsules; Chemistry; Color; Exact sciences and technology; Lactose - analysis; Least-Squares Analysis; Multivariate Analysis; Pharmaceutical capsule; Pharmaceutical Preparations - analysis; Spectrometric and optical methods; Spectrum Analysis, Raman; Transmission Raman measurement
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2011.11.075

► Transmission Raman spectra of samples in glass vials were collected. ► A PLS model was developed using these spectra. ► This model was directly used to determine concentrations of the same samples in capsules of different colors. ► Fluorescence emanating from capsules was reduced by the transmission measurement. ► Accurate determination was feasible without influence of capsule colors seriously. Direct transmission Raman measurements for analysis of pharmaceuticals in capsules are advantageous since they can be used to determine active pharmaceutical ingredient (API) concentrations in a non-destructive manner and with much less fluorescence background interference from the capsules themselves compared to conventional back-scattering measurements. If a single calibration model such as developed from spectra simply collected in glass vials could be used to determine API concentrations of samples contained in capsules of different colors rather than constructing individual models for each capsule color, the utility of transmission measurements would be further enhanced. To evaluate the feasibility, transmission Raman spectra of binary mixtures of ambroxol and lactose were collected in a glass vial and a partial least squares (PLS) model for the determination of ambroxol concentration was developed. Then, the model was directly applied to determine ambroxol concentrations of samples contained in capsules of 4 different colors (blue, green, white and yellow). Although the prediction performance was slightly degraded when the samples were placed in blue or green capsules, due to the presence of weak fluorescence, accurate determination of ambroxol was generally achieved in all cases. The prediction accuracy was also investigated when the thickness of the capsule was varied.