Formation of reactive species that lead to hemoglobin adducts during storage of blood samples.

In monitoring exposure of ethylene oxide or its precursor, ethene, by the measurement of hydroxyethylation of N-terminal valines in hemoglobin, sometimes high, deviating adduct levels were developed during storage of the samples. The time dependence indicated that consumption of a protective factor was involved. The studies show that the effect is specific to certain structures such as hydroxyethyl. Possible mechanisms of the effect were studied in simulation experiments. The artefact formation was enhanced by lyophilization of samples, possibly due to formation of free radicals. H2O2 was weakly effective in producing the artefact. In the presence of Cu2+, H2O2 and methionine hydroxyethyl adducts were formed, possibly in association with ethene production. Until an effective protective factor has been identified it is suggested that, prior to preparation for analysis, samples should be stored as precipitated globins at less than or equal to -20 degrees C. Under these conditions the adduct level is stable for years.