2,6-Dibromoquinone-4-chloroimide is a colorimetric dye for the detection of phenolic compounds. It produces an indigo dye upon reacting with phenolic compounds at a pH of approximately 9.4. 2,6-Dibromoquinone-4-chloroimide has been used as a Gibbs reagent for the colorimetric detection of phenolic compounds. It has also been used in chromogenic reactions for the quantitative colorimetric detection of aflatoxins, causing colorless aflatoxins to become green with an absorption band at 673 nm.
4-Di-2-ASP, a styryl pyridinium fluorescent dye, serves as an essential mitochondrial marker. It effectively and specifically labels pulmonary NEBs (neuroepithelial bodies) [1].
4-Methylumbelliferyl 2-sulfamino-2-deoxy-α-D-Glucopyranoside (4-MU-α-GlcNS) is a fluorogenic substrate of heparin sulphamidase. Heparin sulphamidase cleaves 4-MU-α-GlcNS to yield 4-MU-α-GlcNH2, which is then cleaved by α-glucosaminidase to release the fluorescent product 4-MU, which displays an emission maxima of 445-454 nm. The excitation maxima for 4-MU is pH-dependent: 330, 370, and 385 nm at pH 4.6, 7.4, and 10.4, respectively. 4-MU-α-GlcNS has been used to quantify heparin sulphamidase deficiencies associated with Mucopolisaccaridosis IIIA and other lysosomal disorders.