chapter  2
14 Pages

Basic Principles of Near-Infrared Spectroscopy

WithHeinz W. Siesler

Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.2 The Scattering Technique of Raman Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.3 A Comparison of the Qualitative and Quantitative Aspects of Raman, MIR, and

NIR Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.4 A Comparison of the Basic Instrumentation of Raman, MIR, and NIR

Spectroscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2.5 Important Aspects for the Implementation of Raman, MIR, and NIR

Spectroscopy in Process Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

The increasing demand for product quality improvement and production rationalization in the chemical, petrochemical, polymer, pharmaceutical, cosmetic, food, and agricultural industries has led to the gradual substitution of time-consuming conservative analytical techniques (GC, HPLC, NMR, MS) and nonspecific control procedures (temperature, pressure, pH, dosing weight) by more specific and environmentally compatible analytical tools. In this respect, of the different methods of vibrational (mid-infrared [MIR], near-infrared [NIR] and Raman) spectroscopy, primarily the NIR technique has emerged over the last decade — in combination with light-fiber optics, new in-and on-line probe accessories, and chemometric evaluation procedures — as an extremely powerful tool for industrial quality control and process monitoring.