Residual Hydrogen Determination in Perfluoropolyalkylethers Using Fourier Transform Infrared and Proton Nuclear Magnetic Resonance Spectroscopies

Abstract

The residual hydrogen content of several perfluoropolyalkylether base fluids has been determined with the use of proton nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies. The analysis of standard samples gives a linear calibration curve for hydrogen concentrations between 0.5 and 500 ppm for both FT-IR and NMR. The two methods have similar detection limits of about 1 ppm. Analysis of identical samples of Krytox 143 AC and Krytox 143 AZ by both methods gives results which are in excellent agreement. The two methods also provide information about the chemical environment in which the hydrogen is located. In both of the Krytox samples, the hydrogen is located in CFH groups within the polymer chain.