We demonstrate the application of a handheld fluorometer optimized for UV excitable assays. We demonstrate the measurement of metabolic products as yeast cells germinate in dextrose solution. In particular we measure NADH which is produced during cellular respiration. The handheld fluorometer consists of a CMOS active pixel sensor with in-pixel CDS, coupled with a custom chromophore-polymer emission Alter and a UV LED as the excitation source. The handheld fluorometer is able to detect as little as 10 muM of NADH, and in its present format should be applicable to any fluorescence assay with UV excitation and visible emission wavelengths.