Each biomarker of viability and cytotoxicity has advantages and disadvantages. The choice of which surrogate of health or death to use is greatly influenced by the available detection format and extent of assay time required to reach a result ( Table 2) . Fluorescent formats require short to lengthy incubations with the sample whereas luminescent formats tend to deliver maximal signal windows in a rapid but prolonged fashion. Luminescent formats offer additional utility over fluorescent methods with regard to detection sensitivity, but are also typically more costly to use on a per well basis.