Thermogravimetry – Infrared Spectroscopy (TG-FTIR) Coupled Analysis

ABSTRACT In recent years, coupled or hyphenated techniques have become popular, and have been successfully applied to the solution of many analytical problems. HPLC-MS, tandem MS-MS, GC-FTIR, TLC-FID, GC-MS, etc. are but a few of the familiar abbreviations used for these one step, “double analysis” techniques. The coupling of thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) is a good practical example (TG-FTIR) of such an instrumental approach for solving specific analytical problems. This hyphenated technique provides a quantitative assessment of the process via the TG curve (the thermogram), and an identification of the decomposition products from the IR spectra of the evolved gases. The gases are transferred from the TGA instrument by means of a heated transfer-line to avoid the possibility of condensation. With such a combination, the sample may be introduced into the TGA instrument without any form of chemical or physical modification. Applying the sequential FTIR analysis adds a new dimension to TGA by adding specificity, which it otherwise lacks, to the measurement. An alternate way of of looking at the combination is to consider the TGA instrument as a sample handling or sample treatment front-end to the FTIR, where one can make full use of the interpretive and diagnostic characteristics of infrared spectral analysis. This review reports and summarizes various investigations carried out with TG-FTIR and includes the applications of the technique to many different fields. It will demonstrate clearly that the method is an important tool, not only for the characterization of polymers, but also for the study specific compounds and materials in biological matrices.