Characterization of Solid-State Drug Polymorphs and Real-Time Evaluation of Crystallization Process Consistency by Near-Infrared Spectroscopy.

Herein, we aimed to develop a strategy for evaluating the consistency of pharmaceutically important crystallization processes in real time, focusing on two typical cases of polymorphism. Theoretical analysis using a combination of 13C solid-state nuclear magnetic resonance spectroscopy with other polymorphism analysis techniques identified a number of marker signals, the changes of which revealed the presence of two or more structural orientations (lattices and/or molecular conformations) in both cefazolin sodium pentahydrate (α-CEZ-Na) and cephathiamidine (CETD). The proportions of these forms were shown to be batch-dependent and were defined as critical quality attributes (CQAs) to evaluate process consistency. Subsequently, real-time analysis by chemometrics-assisted near-infrared spectroscopy (NIR) was used to obtain useful information corresponding to CQAs. The pretreated spectra of representative samples were transformed by first derivative and vector normalization methods and used to calculate standard deviations at each wavelength and thus detect significant differences. As a result, vibrational responses of H2O, CH3, and CH2 moieties (at 5,280, 4,431, and 4,339 cm-1, respectively) were shown to be sensitive to the CQAs of α-CEZ-Na, which allowed us to establish a highly accurate discrimination model. Moreover, signals of H2O, CONH, and COOH moieties (at 5,211, 5,284, and 5,369 cm-1, respectively) played the same role in the case of CETD, as confirmed by theoretical results. Thus, we established a technique for the rapid evaluation of crystallization process consistency and deepened our understanding of crystallization behavior by using NIR in combination with polymorphism analysis techniques.

[Temperature compensation for portable Vis/NIR spectrometer measurement of apple fruit soluble solids contents].

Visible (Vis)/near infrared (NIR) spectroscopy has been used successfully to measure soluble solids content (SSC) in fruit. However, for practical implementation, the NIR technique needs to be able to compensate for fruit temperature fluctuations, as it was observed that the sample temperature affects the NIR spectrum. A portable Vis/NIR spectrometer was used to collect diffused transmittance spectra of apples at different temperatures (0-30 degrees C). The spectral data of apple at 20 degrees C was used to develop a norm partial least squares (PLS) model. Slope/bias technique was found to well suits to control the accuracy of the calibration model for SSC concerning temperature fluctuations. The correctional PLS models were used to predict the SSC of apple at 0, 10 and 30 degrees C, respectively. The correctional method was found to perform well with Q values of 0.810, 0.822 and 0.802, respectively. When no precautions are taken, the Q value on the SSC may be as small as 0.525-0.680. The results obtained highlight the potential of portable Vis/NIR instruments for assessing internal quality of fruits on site under varying weather conditions.

[Research on identification of American ginseng and panax ginseng by near infrared spectra of samples' cross section].

In order to identify American ginseng and panax ginseng samples accurately and rapidly, the authors acquired the NIR spectra of the samples' cross-sections. Then the spectra were respectively analyzed according to the samples' physical structure factors and chemical factors. The authors selected appropriate bands and built a physical factor leading model, a chemical factors leading model as well as a comprehensive factor model. The authors found that all the three models' discriminant rates were above 96 percents, which can meet the needs of the rapid detection of raw Chinese medicinal crop materials. While the physical factors model had a simple operation, the discriminant rate was relatively low. The chemical factors model' discriminant rate was higher, but the computation is much more complex. Among the three models, the mixed factor model had the best result with the highest discrimination rate (100 percents) and a smaller number of principal components (4). The effect was the most ideal. It proved that physical factors play an important part in NIR modeling. The cross section method is accurate and convenient which can be used in the quality control in enterprise, realizing the rapid screening of the medicine raw materials.

[Evaluation of walnut by terahertz nondestructive technology].

The deterioration and shell thickness of walnut were studied using the terahertz time domain spectroscopy. Firstly, the THz spectra of moth-eaten, moldy and normal walnuts were compared, and the bad walnuts were properly rejected due to the differences of absorption peaks. Secondly, the transmission-type and reflection-type terahertz time domain spectroscopy system was used simultaneously, and a new formula to calculate shell thickness of walnut was built in the THz system. Then the authors measured the shell thickness based on the detectable refractive index of walnut, and the relative error was 3.7%. Consequently, the quality of walnut was evaluated nondestructively according to physical and chemical indicators from walnut THz spectra respectively.