Quantification and spatial distribution of salicylic acid in film tablets using FT-Raman mapping with multivariate curve resolution

In this study, we proposed a rapid and sensitive method for quantification and spatial distribution of salicylic acid in film tablets using FT-Raman spectroscopy with multivariate curve resolution(MCR). For this purpose, the constituents of film tablets were identified by using FT-Raman spectroscopy, and then eight different concentrations of salicylic acid tablets were visualized by Raman mapping. MCR was applied to mapping data to expose the active pharmaceutical ingredients in the presence of other excipients by monitoring distribution maps and combination of FT-Raman mapping with MCR enabled the determination of lower salicylic acid concentrations. In addition, the distribution of major excipient, lactose, was examined in the tablet form. A calibration curve was obtained by plotting the intensity of the Raman signal at 1635 cm^(-1) versus the concentration of salicylic acid and the correlation was found to be linear within the range of 0.5%–3.9% with a correlation coefficient of 0.99. The limit of detection for the technique was determined 0.35%. The ability of the technique to quantify salicylic acid in tablet test samples was also investigated.

Investigating oil solubilization into nonionic micelles by Raman multivariate curve resolution

Hydrophobic hydration,whereby water spontaneously structures around hydrophobic and amphiphilic molecules,plays a key role in the process of surfactant micelle formation and micellar oil solubilization.Using vibrational Raman multivariate curve resolution spectroscopy,we characterized changes in the hydrophobic hydration occurring within nonionic alkylphenol ethoxylate surfactant Tergitol NP-12 micelles as a function of oil solubilization.We report trends in the changes of hydrophobic hydration depending on the chain length of the oil as well as the presence of a halogen atom in the oil chemical structure.Changes in hydrophobic hydration directly correlate to changes in the physical properties of the micellar solution,including cloud point and micelle hydrodynamic diameter.We compare hydrophobic hydration of Tergitol NP-12 to nonionic linear alkyl ethoxylate surfactant Makon TD-12 and ionic sodium dodecyl sulfate and observe similar trends;the molecular structure of the oil has the largest impact on the hydrophobic hydration.We believe these studies contribute to a fundamental understanding of the importance of hydrophobic hydration in surfactant and oil aggregates,especially as it relates to micellar oil solubilization,and provide insight into how the molecular solubilizate can impact micellar structure,size,and stability.

Optimization of wavelength range and data interval in chemometric analysis of complex pharmaceutical mixtures

The performance of different chemometric approaches was evaluated in the spectrophotometric determination of pharmaceutical mixtures characterized by having the amount of components with a very high ratio. Principal component regression （PCR）, partial least squares with one dependent variable （PLS1） or multi-dependent variables （PLS2）, and multivariate curve resolution （MCR） were applied to the spectral data of a ternary mixture containing paracetamol, sodium ascorbate and chlorpheniramine （150：140：1, m/m/m）, and a quaternary mixture containing paracetamol, caffeine, phenylephrine and chlorpheniramine （125：6. 25：1.25：1, m/m/m/m）. The UV spectra of the calibration samples in the range of 200-320 nm were pre-treated by removing noise and useless data, and the wavelength regions having the most useful analytical information were selected using the regression coefficients calculated in the multivariate modeling. All the defined chemometric models were validated on external sample sets and then applied to commercial pharmaceutical formulations. Different data intervals, fixed at 0.5, 1.0, and 2.0 point/nm, were tested to optimize the prediction ability of the models. The best results were obtained using the PLSlcalibration models and the quantification of the species of a lower amount was sig- nificantly improved by adopting 0.5 data interval, which showed accuracy between 94.24% and 107.76%.