Time-dependent modification of Hb A in normal blood incubated with test compounds. Normal blood from healthy donors was incubated with 2 mM test molecules for 24 h, during which aliquot samples were collected, reduced, and stored until batch analysis by cation exchange HPLC. Levels of modified Hb peaked between 2 and 4 h for all compounds followed by a decline, suggesting that the compounds are subject to metabolism by RBC enzymes. For the esters and alkyl ethers, there was ~92% decline in adduct formation at 24 h, similar to 5-HMF (a,b), while the aryl ethers showed only ~70% decline (c).