NOVELTY - Monitoring and optionally optimizing concentration of an additive composition containing component that inherently provide a fluorescent signal or chemically derivatized to provide the signal in a fuel ethanol involves adding a known amount of the composition to the fuel ethanol to create a treated fuel ethanol; measuring fluorescent signal for the component in the treated fuel ethanol; determining the concentration of the composition in the treated fuel ethanol; and adjusting the concentration of the composition in the fuel ethanol based upon the measure fluorescent signal.    USE - For monitoring and optionally optimizing concentration of an additive composition (e.g. denaturants and corrosion inhibitors) in fuel ethanol (claimed). Also useful for fuel ethanol production and is compatible with all grades of fuel ethanol mixtures.    ADVANTAGE - The method is easy, accurate, and precise method to measure additive dosages in fuel ethanol and to definitively adjust the dosage setpoint as needed; controls additive dosages at fuel ethanol manufacturing plants thus significantly reduces operating costs by preventing inaccurate dosing of treatment chemicals; enables fuel ethanol producers to include certificates of analysis with respect to additive dosage for each fuel ethanol shipment; provides accurate measurements of additive dosages in fuel ethanol for compliance with government regulations; provides a versatile method of monitoring and controlling additive dosages in fuel ethanol that is used in both a grab sample analysis scheme and/or adapted to online dosage control with datalogging capabilities; compensates changes in fuel ethanol system characteristics by adjusting additive dosage; and controls additive dosages at fuel ethanol manufacturing plants to eliminate the possibility of out-of-specification product batches and prevent costly reworking of batches to achieve specification and/or government compliance.    DETAILED DESCRIPTION - Monitoring and optionally optimizing the concentration of an additive composition in a fuel ethanol involves adding a known amount of the additive composition to the fuel ethanol to create a treated fuel ethanol, where the known amount is calculated to provide an optimum concentration range for the additive composition in the treated fuel ethanol, and the additive composition includes a component that is either inherently capable of providing a fluorescent signal or capable of being chemically derivatized to provide the fluorescent signal; measuring the fluorescent signal for the component in the treated fuel ethanol at a point subsequent to adding the known amount of the additive composition; determining the concentration of the additive composition in the treated fuel ethanol based upon the measured fluorescent signal of the component at the point subsequent; if the determined concentration of the additive composition is above the optimum concentration range, optionally diluting the treated fuel ethanol by adding a known additional volume of the fuel ethanol, where the additional volume is calculated to bring the concentration of the additive composition in the treated fuel ethanol into the optimum concentration range; if the determined concentration of the additive composition is below the optimum concentration range, optionally adding an additional known amount of the additive composition, where the additional known amount is calculated to bring the concentration of the additive composition in the treated fuel ethanol into the optimum concentration range; and optionally repeating the steps until the determined concentration of the additive composition is within the optimum concentration range. The component of the additive composition is an inert fluorescent tracer, which is not normally part of the additive composition and is added either simultaneously or sequentially with the additive composition in a known proportion. The component does not inherently provide the fluorescent signal and including chemically derivatizing the component in a grab sample with a moiety to enable the component to provide the fluorescent signal, where the chemical derivatization optionally produces a covalent bond or complex formation between the component and the moiety. The additive composition includes additional compounds. The treated fuel ethanol is mixed with gasoline to form a fuel ethanol composition. The fluorescent signal is used to determine total ethanol content in the fuel ethanol composition. An INDEPENDENT CLAIM is included for a digital storage medium having computer-executable instructions stored on the medium, where the instructions are operable to execute the monitoring method.