Near-infrared spectroscopy--its versatility in analytical chemistry.

The purpose of this review article is to outline recent progress in near-infrared (NIR) spectroscopy. Some particular emphasis is put on the delineation of its versatility in analytical chemistry. NIR spectroscopy is versatile in many aspects. For example, it is electronic spectroscopy as well as vibrational spectroscopy. It is also all-round in applications from basic to practical applications. NIR spectroscopy can be applied to various kinds of materials, bulk materials, thin or thick polymers, tablets, human bodies, and so on. It is particularly powerful in non-invasive, non-destructive, and in situ analysis. In this review, the principles and advantages of NIR spectroscopy are described first, and then its applications to various fields, including polymer science, on-line monitoring, inorganic material research, medical diagnosis, and NIR imaging are introduced.