Effects of dextran on five biuret-based procedures for total protein in serum

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 31; no. 12; pp. 2018 - 2019
• Main Authors: Barnes, DB, Pierce, GF, Lichti, D, Landt, M, Koenig, J, Chan, KM
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.12.1985; American Association for Clinical Chemistry
• Subjects: Adult; Analysis of complex biological substances; Analytical, structural and metabolic biochemistry; Autoanalysis; Biological and medical sciences; Biuret; Blood and biological fluids; Blood Proteins - analysis; Centrifugation; Dextrans; Female; Fundamental and applied biological sciences. Psychology; Humans; Polyethylene Glycols; Urea - analogs & derivatives; Dextran; Assay; Biological fluid; Automation; Automatic analyzer; Clinical biology; Interference; Serum; Serum protein; Biuret method; Blood; Blood plasma
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/31.12.2018

We evaluated the effect of dextran on values for total protein in serum as measured by the biuret method with five widely used automated instruments: the American Monitor Parallel; the Du Pont aca II; the Roche Cobas-Bio; the Kodak Ektachem 400; and the Beckman Astra 8. Dextran concentrations as great as 25 or 30 g/L had relatively little or no influence on total protein measurements by the latter three instruments. Dextran concentrations exceeding 6 g/L caused falsely low results with the aca, whereas the Parallel gave falsely high results when the dextran concentration exceeded 2 g/L. The aca total protein procedure could be protected from the interference by dextran concentrations up to 30 g/L by injecting 0.4-0.8 mL of ethylene glycol directly into the reagent pack before sampling. However, we could not eliminate the interference with the Parallel procedure by any simple means; we thus recommend that it not be used for measuring total protein in serum samples from patients who are being treated with dextran.