Rapid estimation of the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique.

The glycerol concentration of frozen-thawed red cells must be less than 2 percent to prevent hemolysis upon transfusion. Three methods were investigated for monitoring the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique. The supernatant osmolality and glycerol concentration were determined on 47 units of frozen-thawed red cells prepared by agglomeration, and were found to be linearly related (r = 0.83, p less than 0.001). The supernatant refractive index was determined on 29 of the same units. There also was a linear relationship between the refractive index and the glycerol concentration (r = 0.74, p less than 0.001). The relationships were different from those previously reported for red cells prepared by other methods. The simulated transfusion test was done on red cells from three units whose glycerol concentration had been artificially elevated. The simulated transfusion test was found to be sensitive to glycerol concentrations above 2 percent. All three of the methods evaluated can be used to estimate the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique.