Process Monitoring Applications of Multiple Internal Reflection Spectroscopy
Infrared spectroscopy one of the first analytical methods to appear at the beginning of the modem instrument era still is one of the most widely applied analytical techniques. Although infrared analysis has been used primarily for qualitative identification in recent years, the early commercial applications were quantitative measurements on samples from process streams. Multiple internal reflection (MIR) overcomes the need for short path length liquid cells. To obtain the absorption information from which the quantitative data can be computed, it is necessary only to bring the sample in contact with the MIR optical element. The MIR optical element provides the short effective pathlength required. However, chromatographic methods are generally more capable of giving accurate measurements of lower concentrations of individual components and of analyzing complex mixtures containing six or more components.