Bromophenol Blue, an acid phthalein dye, is utilized both as a tracking dye for electrophoresis and as a pH indicator with a transition range of pH 3 to 4.6.

Instructions
1. Solvent selection: Bromophenol blue is usually dissolved in water, but can also be dissolved in organic solvents such as ethanol or DMSO depending on the specific experimental needs.
2. Electrophoresis tracking: Bromophenol blue is often used as a tracking dye in gel electrophoresis. It migrates with the sample and helps monitor the progress of the electrophoretic separation process.
Concentration: Typical concentrations are 0.01% to 0.1% (w/v).
Directions: The dye is mixed with the sample and loaded into the gel.
3. pH indicator: Bromophenol blue is a pH indicator that can change in the pH range of 3.0 to 4.6. It is yellow at low pH and blue at high pH.
Directions: Prepare a diluted Bromophenol blue solution for monitoring pH changes in buffers or solutions.
Protein detection: Bromophenol blue can be used to detect proteins by binding to the protein, which causes a color change that can be detected by spectrophotometry.
4. Absorption peak: When bound to proteins, Bromophenol blue produces a strong absorption peak at 610 nm. Sensors for chemical detection: Bromophenol blue can also be used as a sensor to detect a variety of compounds such as ammonia, drugs, proteins, and amino acids because it undergoes a color change when bound to these substances.