Abstract: A method of treating of glycosylated hemoglobin and in particular the process of hemoglobin isolation and preparation of a stable glycosylated hemoglobin in which the glycosylated hemoglobin remains liquid. The method comprises steps including separating human red blood cells from anti-coagulated blood, washing the human red blood cells with physiological saline and centrifuging the red blood cells and aspirating and discarding a resulting supernatant and white blood cell layer, lysing the packed red blood cells, mixing and freezing the cell/water mixture, defrosting, centrifuging, filtering and saving the supernatant, heating the supernatant, diafiltering the adjusting the hemolysate so that a final hemoglobin concentration is within specified limits. Additives may include potassium cyanide, carbon monoxide, and appropriate preservatives.

Abstract: A stable human serum based control for the assay of Total LD and CK and their isoenzymes. This control may be lyophilized and reconstituted and still provide the same enzyme activity prior to lyophilization, for seven (7) days after reconstitution, if stored in the dark at or about 2.degree.0 to 8.degree. C. No thiol compounds other than the amount normally used to purify CK isoenzymes are found in this highly stable control.