"Goldberg Validations": Refractometric Protein Concentration Calibration of Pooled Source Plasma and Validation of Clinical Serum Protein Refractometers

Anderle Heinz,Zlabinger Stefan,Herbinger Karin,Weber Alfred

doi:10.35840/2633-8912/2418

Abstract

Conflicting historical data for the specific refractive index increment dn/dc of human plasma/serum protein have warranted an experimental re-calibration for citrated source plasma for fractionation. Measurements by <em>Dumas</em> combustion and digital refractrometry applied the pharmacopeial protein-nitrogen ratio of 6.25. The non-protein matrix was separated by centrifugal ultrafiltration. Refractometric data agreed excellently with <em>Dumas</em>-based protein concentrations.

Highlights

We have described the refractometric calibration of albumin and of purified immunoglobulin G based on nitrogen-based protein concentration values [1]
The present work demonstrated the practical benefits of digital refractometry
The dn/dc value obtained for pooled plasma (0.0001942 mg/mL) is considerably higher than the single literature value as given at the beginning of commercial plasma fractionation [2], but practically the same as the value stated for plasma first in 1928 (0.000195 mL/mg) [10], as the experimental result determined by the permeate subtraction technique in 1923 for human serum [7], and as the value of dialyzed serum given in 1952 (0.000193 mL/mg) [12]

Summary

Introduction

We have described the refractometric calibration of albumin and of purified immunoglobulin G based on nitrogen-based protein concentration values [1]. In the first 50 years of refractometry, defibrinated blood serum had been a much more common sample material than blood plasma. Analytical attention towards the latter has arisen only with the introduction of pooled plasma for transfusion [16], and the establishment of the coldethanol plasma fractionation [17]. Several theses at European hematological departments had focused on the application of refractometry on plasma and serum samples, these apparently did not find wider distribution and attention (Supplemental Material)

Methods

Results

Conclusion