A candidate reference method for determination of total protein in serum. I. Development and validation

Area of Science:

• Clinical Chemistry
• Biochemistry
• Analytical Chemistry

Background:

• Accurate measurement of total serum protein is crucial for diagnosing various medical conditions.
• Existing methods may be subject to interferences, necessitating the development of a robust reference method.

Purpose of the Study:

• To develop and validate a candidate Reference Method for total serum protein quantification.
• To assess the reliability and accuracy of the biuret reaction-based method.

Main Methods:

• Utilized a previously described biuret reagent and Standard Reference Material (SRM) 927 bovine albumin.
• Evaluated color development stability at 25°C over 30 and 60 minutes.
• Assessed interference from glucose, bilirubin, hemoglobin, dextran, therapeutic antibiotics, and triglycerides.

Main Results:

• Identical serum protein values were obtained with 30 or 60 minutes of color development at 25°C.
• Minimal interference observed from glucose, bilirubin, antibiotics, and triglycerides within specified concentrations.
• Hemoglobin showed a minor increase in apparent serum protein (0.4 g/L at 3 g/L).
• Dextran interference was eliminated by centrifuging the reaction mixture.
• Within-run and day-to-day standard deviations were 0.1 g/L and 0.4 g/L, respectively.

Conclusions:

• The developed biuret reaction method serves as a reliable candidate Reference Method for total serum protein measurement.
• The method demonstrates high accuracy and minimal interference, making it suitable for clinical laboratory use.
• Further validation can establish this method as a standard for total serum protein analysis.