Abstract: Apparatus and methods for combining multiple modes and methods of optical detection, postprocessing, and/or feedback loops in bioanalytical measurements. The methods may include (1) positioning a composition at an examination site in a multi-mode instrument; (2) detecting light transmitted form the composition using the multi-mode instrument in a first optical measurement mode; (3) detecting light transmitted from the composition using the multi-mode instrument in a second optical measurement mode, the second mode being different than the first mode; and (4) computing a quantity related to a property of the composition using the light detected in at least one of the optical measurement modes. These steps may be performed on one or more samples, simultaneously and/or sequentially. The quantity may relate to photoluminescence, chemiluminescence, absorption, and/or scattering, among others.