A New Method of Sample Preparation for Infrared ATR Spectrophotometry
Pyrolysis has proved to be a useful and interesting adjunct to the ATR technique. Samples containing fillers such as carbon can be pyrolyzed under various conditions of time and temperatures and the pyrolyzates deposited directly on an ATR crystal. This procedure enables the analyst to by pass an extraction or other separation step. A further advance in this technique has been made by putting a high voltage charge on the crystal in order to facilitate the deposit of pyrolyzates on the crystal. When used in this manner the crystal functions as one side of a capacitor. This technique makes it possible to use smaller samples and in some cases lower temperatures. Applications based on the pyrolysis of various small molecules as well as polymers will be discussed. The apparatus used to prepare the condensates on the ATR crystal will be described. Similarities to and departures from the spectra of the parent molecules when compared to the spectra of pyrolyzates will be considered.