A differential pulse polarographic serum protein assay

Area of Science:

• Analytical Chemistry
• Biochemistry
• Electrochemistry

Background:

• Human serum and albumin exhibit a distinct differential pulse polarographic signal around -0.6 V.
• Accurate quantification of total serum protein is crucial for clinical diagnostics and biochemical research.

Purpose of the Study:

• To investigate the utility of differential pulse polarography for quantifying total serum protein.
• To determine the optimal conditions (pH, concentration) for polarographic analysis of serum and albumin.
• To assess the interference of cellular components and the applicability of bovine serum albumin (BSA) as a standard.

Main Methods:

• Differential pulse polarography was employed to analyze human serum and albumin solutions.
• Experiments were conducted at different pH levels (7.0 and 12.6) and concentrations.
• Standard curves were generated using bovine serum albumin (BSA) to correlate polarographic response with protein concentration.

Main Results:

• A linear relationship between polarographic response and concentration was observed for dilute solutions (< 7 µg/ml) at pH 7.0.
• A near-linear response was achieved up to 70 µg/ml at pH 12.6, although equilibration was slow.
• The polarographic assay using BSA yielded a correlation coefficient of 0.89 for total serum protein.
• Cellular constituents in whole blood did not interfere with the assay.
• The correlation with BSA was not maintained for protease-digested serum or albumin.

Conclusions:

• Differential pulse polarography is a viable method for quantifying total serum protein, particularly at low concentrations and neutral pH.
• Bovine serum albumin can serve as a suitable standard for this assay, provided the serum has not undergone proteolysis.
• The method is robust against interference from blood cells, enhancing its potential for clinical applications.