Solid-phase extraction of a carcinogen, 4,4'-methylenedianiline, in serum

Polyurethane (PU) is a material used to make medical devices. During the gamma-ray or autoclave sterilization of these medical devices, PU degrades and a carcinogen, 4,4'-methylenedianiline (MDA), is produced. We studied a pretreatment method for MDA in blood serum by solid-phase extraction. Using Bond Elut C18, phenyl, and cyclohexyl columns, MDA in serum at a concentration of 0.1-10 ppm was 100% recovered with no apparent difference between the columns tested. Elution was carried out with methanol containing 1M MH4OH. The recovery rate of serum MDA with a Bond Elut C8 column was 90%, less than that from the above columns. The recovery of serum MDA from Bond Elut C1, C2, and silica was unsatisfactory. The recovery rate with Bond Elut SCX (strong cation exchange column) proved satisfactory, but the pretreatment of serum was troublesome as both deproteinization and centrifugal separation procedures were necessary in addition to the complicated conditioning procedure of the SCX column. There was no significant difference in recovery rate among C18, phenyl, and cyclohexyl columns, indicating that both pi-pi binding between benzene rings and van der Waals binding would be predominant. Because Bond Elut silica showed a lower recovery rate, the binding of NH2 in MDA with free silanol would not be predominant.