Our Amplite™ Fluorimetric Glutathione Assay Kit provides an ultrasensitive fluorimetric assay to quantitate GSH in sample. The proprietary non-fluorescent glutathione sensor used in the kit becomes strongly green fluorescent upon reacting with a GSH compound, which has the spectral properties almost identical to those of fluorescein and can be easily read by a fluorescence microplate reader at Ex/Em = 490/520 nm. The kit can detect as little as 1 picomole of GSH in a 100 µL assay volume (10 nM). In addition, both absorption and emission spectra of the glutathione adduct are pH-independent, making this assay kit highly robust. The assay can be performed in a convenient 96-well or 384-well microtiter-plate format and easily adapted to automation without a separation step.