Modification of Benning's infrared method permits determination of the quantity of water in Freon 22 ® The Freon 22 is diluted with Freon 12® of known moisture content and the apparent moisture concentration determined by measuring the absorption of 2.67 μ radiation. From previously determined empirical data, the water equivalent value of the Freon 22 can be determined. Subtraction of the water equivalent value of the Freon 22 and the known water content of the diluent from the apparent moisture concentration is then the moisture concentration of the Freon 22.
W. J. Diamond, "Water Determination in "Freon-22" Refrigerant by Infrared Spectrophotometry," Appl. Spectrosc. 13, 77-78 (1959)