Chemical Reaction Of Lead-free Gasoline Additives MTBE And TBA With Biological Macromolecules In Vivo Studied By AMS

The addition of oxygen containing compound to gasoline may remarkably increase the anti-knock ability as well as the burning efficiency of gasoline for the light duty vehicles. Hence, that reduces the exhaust emission of CO, O₃ and volatile organic compounds (VOCs) and greatly improves the air quality in environment. Because methyl tert-butyl ether (MTBE) possesses some marked merits, such as low cost, good miscibility with gasoline, low vapor pressure and boiling point in blending and easy production and transportation, nowadays it has been a most worldwide used gasoline additive substituting for the lead-containing anti-knock additive for the light duty vehicles. Tert-butyl alcohol (TBA) is soluble in organic solvent. While blending with methanol it can also be used as an additive to increase the octane value of gasoline. It is noted that TBA is one of the in vivo metabolites of MTBE.In the present thesis, we report the dose response and time course of the adduction of MTBE and TBA with the biological macromolecules, DNA and proteins at the molecular level using the ultra-sensitive Accelerator Mass Spectrometry (AMS). The experimental results are presented in four items as follows:1. The MTBE-DNA adducts in mouse liver/lung/kidney were measured with AMS. We, for the first time, observed the definite adduction of MTBE with DNA of mouse liver, lung and kidney in a positive dose-response relationship. In addition, a good linear correlation between the liver/lung/kidney DNA adducts level with Hb (hemoglobin) adducts level was observed. Thus, we suggested that MTBE-Hb adducts could be a good surrogate of MTBE-DNA used as a biomarker for MTBE exposure. Besides, MTBE-SA adducts could also be used as a biomarker for MTBE exposure.2. The time course of the MTBE-DNA adducts of mouse liver/lung was measured. The MTBE-DNA adducts level in liver/lung peaked at several h post dosing. After that the concentration decreased rapidly until 5 d, then declined slowly. The decay of adducts implies that the MTBE-DNA adducts can be partly eliminated by the DNA repair.