The identification of barbiturates by attenuated total reflectance

The use of Attenuated Total Reflectance as an analytical technique in infrared spectroscopy has become increasingly important in the past few years. ATR (Attenuated Total Reflectance) is a relatively new analytical method. Producing spectra of compounds by this method requires no solvent for dissolving the sample and no salts for making pellets. The only requirements for spectra production, similar in quality to those produced by conventional methods, are that there is enough sample to cover both sides of the reflector be similar. The index of the sample is fixed; therefore, the index of the reflector is controlled by selecting a reflector with one similar to the sample. Reflectors with indices from 1.2 to 4.12 are commercially produced. Since no solvents or salts are used in ATR, this method allows complete recovery of the sample without using separation or abstraction processes. The elimination of solvents and salts should also lower the cost of spectra production. The ATR method eliminates the weighing and measuring of samples and salts and the time consuming process of pellet making; therefore, it should be a quicker method than any of the conventional methods. The principles of ATR have been applied to several fields of infrared analysis. Harris and Svoboda used ATR as a means of determination of Alkyl and Monomer Modified Resins; Katlaksky and Keller used ATR to study aqueous solutions. Ahliyah and MOoney used ATR in preparing spectra of Polyatomic Anions, and Deley and Liotti used ATR as a means of identifying coating on paper. Materials for which ATR has been useful in analysis include fabrics, polymers which cannot be easily prepared for other types of analysis, and surfaces of semiconductors. In this project, spectra of several pure barbiturates, drug compositions containing barbiturates, and several related compounds were prepared using ATR; these were compared to spectra produced by the conventional pellet method