Solubility of freon-22 in blood and lung tissue

Despite the frequent use of freon-22 (e.g. to measure pulmonary blood flow), there is no agreement on its solubility in water or body fluids. The values in the literature vary, often quoted without reference to measurement or identification as Ostwald or Bunsen coefficients. We used a Schölander apparatus and determined the Bunsen solubility coefficient (mlgas.(mlfluid.atmosphere)-1) at 37 degrees C as: 0.476 in water; 0.673 in human whole blood; 0.479 in human plasma; 0.662 in canine whole blood; 0.437 in canine plasma; and 1.077 in homogenized canine lung tissue. As pure freon was used, these solubilities may not be applicable if freon-22 does not obey Henry's law. In man, the Ostwald solubility coefficient is calculated as 0.76 ml/ml whole blood at BTPS. These results provide information for further studies involving freon-22, and clear the confusion which has arisen from poorly defined solubility coefficients.