Overestimation of glucose in uranyl acetate-treated samples: modification of the deproteinization method

It is demonstrated that uranyl ions remaining in deproteinized supernatants of blood, serum, or liquor cerebrospinalis lead to falsely elevated glucose values by forming insoluble precipitates of uranyl phosphate. Furthermore, glucose is overestimated in hemolytic blood samples because of the UV-absorption of incompletely precipitated hemoglobin. A modified deproteinization method is recommended which overcomes these problems: the specimen volume is reduced to one half of the usual volume (0.05 instead of 0.1 ml) and excess uranyl ions are removed from the deproteinized supernatant by precipitation as uranyl phosphate, using phosphate-coated tubes. The supernatant obtained after centrifugation is free of uranyl ions and hemoglobin. Therefore, a sample blank may be omitted.