Stability of Protein, Enzyme, and Nonprotein Constituents of Stored Frozen Plasma. Use in Standardization and Control of Chemical Procedures

Abstract

This paper is primarily concerned with the subject of quality-control in the clinical laboratory. The stability of frozen outdated blood bank plasma over a 6 months interval of storage is reported for 15 commonly analyzed constituents. These constituents are: albumin, globulin, total protein, urea, nonprotein nitrogen, uric acid, creatinine, cholesterol, glucose, bilirubin, chloride, amylase, cholinesterase, alkaline phosphatase, and acid phosphatase. Statistically significant quantitative change was noted in 3 constituents after the period of storage: nonpro-tein nitrogen, glucose, and alkaline phosphatase. The use of frozen plasma for quality-control, as a partial substitute for "pure" standards, and for comparing the precision of chemical methods used in the clinical laboratory, are discussed.