Ring test for low levels of N-(2-hydroxyethyl)valine in human hemoglobin

Hemoglobin adducts are useful for the identification and quantification of electrophilic agents in vivo. A modified Edman degradation method has been extensively used for monitoring exposure to ethylene oxide through gas chromatographic-mass spectrometric measurements of hydroxyethyl adducts to the N-terminal valines in hemoglobin. In a ring test, four laboratories using different versions of the method analyzed eight human globin samples with low adduct levels from ethylene oxide. Measurements of the same adduct by a radioimmunoassay were also included. Strong correlation between the measurements by the different laboratories shows that the method in principle works well. However, there were some systematic quantitative differences.