The Application of Infrared Spectrophotometry to Quantitative Measurements: Statistical Studies of Absorption Intensity Reproducibility

Abstract

Because of its imporatnce in quantitative measurements, the degree of reproducibility of infrared absorption intensity measurements during one day, from day to day, and over an extended time interval of several months, has been studied. Polystyrene films and wire screens were proved to have satisfactory stability for use as standard samples in this study. Absorbance values used in this study were collected on a custom built double beam instrument as well as on two Perkin-Elmer double beam instruments. The data have been treated statistically. Comparable absorbance reproducibility was obtained with all three instruments but absorbance level shifts were observed. Instrumental, operational and sample variables which contribute to lack of absorbance reproducibility have been considered. Recommendations are included which should interest instrument users as well as instrument producers.