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Methanol content is a key parameter in the fermentation industry. However, the methanol concentration during fermentation is usually quite low, it's necessary to find a method to measure methanol with low content, even indirectly. Near infrared spectroscopy (NIRS) technology is rapid and non-destructive, which can provide analytical solutions for components that represent approximately 1%. Aquaphotomics gives the chance to dig into the information remaining hidden in the NIR spectra, which shows a distinct advantage if the target object is presented in lower concentrations. Therefore, NIRS combined with aquaphotomics was introduced in this study to prove the feasibility for methanol determination at 0.1%–2.5% (v/v) in aqueous solutions. Determination coefficient of calibration (R2c), validation (R2p) and cross validation (R2cv), root mean square error of calibration (RMSEC), validation (RMSEP) and cross validation (RMSECV) were applied to verify the performance of the partial least squares regression (PLSR) models, and the corresponding values of best model were 0.999, 0.999, 1.000, 0.0204%, 0.0277%, 0.0142%, respectively. Our successfully result indicated that NIRS technique combined with aquaphotomics may open a new perspective in methanol determination.

The in vitro dissolution profile is a key parameter which reflects the quality of sustained-release tablets. Most studies were used to determine the dissolution of tablets utilizing dissolution curves. This study aimed to investigate the role of water during nifedipine controlled release tablets dissolution process in order to provide a new way to understand the dissolution behavior. Dissolution liquid was added to the drug-containing layer slowly, and near infrared spectra were acquired according to the set time. NIR spectroscopy with aquaphotomics were introduced to determine different water patterns. The results showed that, the structural change of water was consistent with the dissolution process. During hydration stage, it was mainly Sr combined with the semi-permeable membrane to form a channel. Then S0, S1, S2 and S3 combined with the drug layer and the push layer. Finally, it was relied on the swelling of the push layer to push the drug layer out at the release process. This study not only deepens the understanding of the dissolution process, but also opens a new perspective in molecular interaction analysis in aqueous system by understanding the roles of water.

In this study, human albumin (HA) content was determined by near infrared spectroscopy (NIRS), which was an process analytical technology (PAT) tool, to realize process monitoring during acid precipitation. Eight batches of acid precipitation process samples were simulated in laboratory, and HA contents were determined by bromocresol green (BCG) method. Five batches were selected as calibration set and three batches were selected as validation set to build partial least squares regression (PLSR) model of HA content. Before the establishment of PLSR model, partial samples and different variable selection methods were compared in details and 35 variables were finally selected. The results showed that the successive projection algorithm (SPA) combined with the multi-variable selection methods (CC, UVE, CARS, SCARS, FiPLS, MWPLS, BiPLS) could obtain more useful information than the single method. The RMSECV and RMSEP values of the optimal PLSR model were 0.7038 g/L and 0.5893 g/L, respectively. Meanwhile, the results indicated that NIRS was an effective tool and could be successfully used for quantitative monitoring during acid precipitation process. To some extent, it could provide theoretical supports for quality control with a fast, nondestructive and low-cost NIRS in monitoring the complex biological production process.