The initial concentration of a drug decomposing according to first order kinetics is28 units/mL. The specific decomposition rate, k, obtained from an Arrhenius plot is 2.09 × 10-5 hr-1 at room temperature, 25°C. Previous experimentation has shown that when the concentration of the drug falls below 15 units/mL it is not sufficiently potent for use and should be removed from the market. What expiration date should be assigned to this product?