ABSTRACT
Internal reflectance is not a new technique for infrared analysis in the industrial laboratory or for industrial process measurements. However, until the early to mid-1980s its role in day-to-day infrared analyses was limited. The main reasons for its limited use were the relatively low performance of routine infrared instruments, the cumbersome nature of the older style internal reflectance accessories, and the inability to take full advantage of the spectral data produced (in terms of numerical processing). This chapter reviews internal reflectance from a practical point of view, as it pertains to meeting the needs of modem industrial analysis. For many years biological and biopharmaceutical analyses were considered to be impossible by infrared spectroscopy. This attitude was based on the limitation of sampling aqueous-based systems and the inability to extract the relevant data from a resultant spectrum, even if a spectrum could be obtained.
