Purpose

This procedure utilizes Fourier transform infrared spectroscopy to measure the carbon dioxide concentration within carbonated beverage containers.

Description

CO₂ absorbs IR radiation in a very specific range of wavelengths. As the concentration of carbon dioxide decreases the measured CO₂ absorption correspondingly decreases. The IR absorption value is divided by the length of the path through the container to account for the change in the container shape (there is usually a slightly shorter path length by end of test) over the time of the test. This calculation yields a concentration value for a particular sample. The concentration is then plotted against time to determine the rate of CO₂ loss. The typical test time is 49 days with an interim report at 25 days.