Given the labor-consuming nature of model establishment, model transfer has become a considerable topic in the study of near-infrared (NIR) spectroscopy. Recently, many new algorithms have been proposed for the model transfer of spectra collected by the same types of instruments under different situations. However, in a practical scenario, we need to deal with model transfer between different types of instruments. To expand model applicability, we must develop a method that could transfer spectra acquired from different types of NIR spectrometers with different wavenumbers or absorbance. Therefore, in our study, we propose a new methodology based on improved principal component analysis (IPCA) for calibration transfer between different types of spectrometers. We adopted three datasets for method evaluation, including public pharmaceutical tablets (dataset 1), corn data (dataset 2), and the spectra of eight batches of samples acquired from the plasma ethanol precipitation process collected by FT-NIR and MicroNIR spectrometers (dataset 3). In the calibration transfer for public datasets, IPCA displayed comparable results with the classical calibration transfer method using piecewise direct standardization (PDS), indicating its obvious ability to transfer spectra collected from the same types of instruments. However, in the calibration transfer for dataset 3, our proposed IPCA method achieved a successful bi-transfer between the spectra acquired from the benchtop and micro-instruments with/without wavelength region selection. Furthermore, our proposed method enabled improvements in prediction ability rather than the degradation of the models built with original micro spectra. Therefore, our proposed method has no limitations on the spectrum for model transfer between different types of NIR instruments, thus allowing a wide application range, which could provide a supporting technology for the practical application of NIR spectroscopy.

Aquaphotomics, water, water absorbance spectral pattern (WASP), near-infrared spectroscopy (NIR), chemometrics, water species

Hyaluronic acid (HA) is a kind of biological macromolecule with strong water binding ability. It has rich biological functions and plays an important role in the living body. It has extremely high application value in the fields of medical beauty, medicine, medical treatment and food. In the past, the thinking of studying HA was rather rigid, which is reflected in the direct study of HA itself, which is quite difficult in a complex system because there are too many influencing factors in the real biological environment. The proposal of aquaphotomics allows researchers to focus on the water molecules in complex biological systems, which leads us to shift the angle of thinking about HA-related issues to the water molecules that are closely bound to it. In previous and ongoing work, we use spectroscopy technology and aquaphotomics to study water species, focus on the widely used HA and its derivatives on the market, and apply multivariate analysis methods to analyze the interaction between HA and water molecules to further clarify the material properties of HA form the basis for monitoring its process of binding water in the body. This paper briefly reviews important knowledge concerning the relationship between HA and water, and explains our past and ongoing related research in this field. Key words: hyaluronic acid, water, aquaphotomics, spectroscopy

Drug polymorphism is an important factor affecting the drugs quality and clinical efficacy. Therefore, great attention should be paid to the crystal analysis of drugs with their researching and evaluating part. With the booming development of Raman spectroscopy in recent years, more and more crystal analysis investigations were based on vibrational spectroscopy. This review mainly discussed the qualitative and quantitative analysis of active pharmaceutical ingredients (API) and pharmaceutical preparation with Raman spectroscopy. On basis of the determination of the vibration mode of drug molecules and the analysis of their chemical structure, this method had the advantages of universal, non-destructive, fast determination, low samples and cost, etc. This review provides theoretical and technical support for crystal structure, which are worth popularizing. It is expected that it will be helpful to relevant government management institutions, pharmaceutical scientific research institutions and pharmaceutical manufacturers.