Neutralization level must be determined after an ionomer is synthesized as varying the neutralization level varies the morphological and physical properties of the ionomer. One method used to do this is to examine the peak heights of infrared vibrations of the acid form. However, there may be substantial error in determining peak height, especially since small amounts of water appear in the same wavenumber range. Titration of the acid groups is another method that can be used, though this is not possible in some systems.