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™ FAM SSL-NHS ester contains a S-S linker that can be cleaved with TCEP or DTT to remove the fluorescein (FITC) fluorophore from the target molecule. 5-FAM has the same fluorophore identical to the common 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.