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Infrared Attenuated Total Reflection Spectra of Aqueous Solutions of Some Amino Acids

Volume 18, Number 2 (March 1964) Page 62-63

Robinson, Frank P.; Vinogradov, Serge N.


The technique of total reflection proposed by Harrick (1) using total internal reflection and by Fahrenfort using a single reflection (2) (attenuated total reflection, ATR) seems to hold great promise as opposed to conventional reflection techniques, for the structural and analytical investigations of difficult samples in the infrared region of the spectrum (3,4). Because of the intense absorption by water, the examination of infrared absorption spectra of aqueous solutions requires the use of very thin sample cells with reference beam attenuation or of carefully matched sample and reference cells. It was decided to investigate the possibility of obtaining the infrared ATR spectra of aqueous solutions of some amino acids using the single-reflection ATR accessory available from Barnes Engineering Co., Stamford, Conn. with a prism of AgCl as the reflecting material; the spectra were obtained on a Perkin Elmer model 421 double-beam, infrared spectro-photometer. The angle of reflection was 45°; the slit program was set at 1000, the gain at 5, and source current 0.35 amp. The amino acids used were from commercially available sources.