A computer-implemented method includes controlling an instrument to measure a fluorescence emission spectrum of a sample including a first peak emission wavelength and at least a second peak emission wavelength, emitted in response to an excitation wavelength and controlling the instrument to measure an absorbance obtained at the excitation wavelength of the sample. The method may include determining, using the computer, a ratio of the measurements at either the second peak emission wavelength, or a sum of measurements at a plurality of peak emission wavelengths including at least the first peak emission wavelength and the second peak emission wavelength, to the first peak emission wavelength, and calculating, using the computer, a value for a quality parameter based on a combination of at least the ratio and the absorbance measurement. The method may include controlling an associated process based on the quality parameter.