Fluorescence-based methods have many advantages for biological detections in terms of sensitivity and convenience. Many biological molecules can be readily labeled with a fluorescent tag for fluorescence imaging and flow cytometry analysis. However, most of the existing fluorescent tags are used to permanently labeling biological targets from which the added fluorescent tags cannot be cleaved for further downstream analysis, such as mass spectral analysis or another detection mode. AAT Bioquest’s ReadiCleave™ linkers enable fluorescent tags conjugated to a biological target from which the added fluorescent tag can be removed when needed. ReadiCleave™ iFluor® 488 SSL-NHS ester contains a S-S linker that can be cleaved with TCEP or DTT to remove the iFluor® 488 fluorophore from the target molecule. iFluor® 488 has almost identical spectra of Alexa Fluor 488 with high fluorescence quantum yield and improved stability compared the traditional FITC dye. The cleavage can be carried out by adding DTT or TCEP solution and incubating from room temperature to 65 °C for 1-10 min.