An evaluation of ethylene glycol-based liquid specimens for use in quality control.

We investigated the analytical acceptability of ethylene glycol-based control sera by preparing sets of aqueous and ethylene glycol-based specimens that had added uric acid, calcium, creatinine, glucose, urea, sodium, and potassium. Ethylene glycol caused a significant systematic proportional bias in procedures involving dialysis, but had no discernible effect on methods not involving dialysis. The extent of bias was proportional to the concentration of ethylene glycol, was independent of protein concentration, and differed according to the type of dialysis system used. We conclude that ethylene glycol-based control materials can have useful applications in clinical chemistry, but caution must be exercised in their use with analytical systems that employ dialysis.