M-Methyl Red CAS 20691-84-3

1. m-Methyl red CAS 20691-84-3 is primarily used as a pH indicator in analytical chemistry, exhibiting a distinct color change from red at pH 2.0 to yellow at pH 4.0 .
2. m-Methyl red serves as a key reagent in acid-base titrations, particularly for detecting endpoints in reactions involving weak bases and strong acids.
3. In microbiology, m-methyl red is employed in the MR-VP test to differentiate bacterial species based on their ability to produce mixed acids via glucose fermentation; a red color indicates a positive result.
4. Researchers utilize this azo dye in environmental monitoring to assess water acidity and in general laboratory settings for visual pH assessment within the acidic range .

1. m-Methyl red CAS 20691-84-3 must be stored in a tightly sealed container in a cool, dry, and well-ventilated environment, protected from light and moisture .
2. m-Methyl red is classified with acute toxicity (oral, Category 5) and may be harmful if swallowed; it can also cause skin, eye, and respiratory tract irritation.
3. Personnel must wear chemical-resistant gloves, tightly fitting safety goggles with side-shields, and protective clothing when handling this substance to prevent contact with skin and eyes .
4. Keep m-Methyl red away from incompatible materials such as strong oxidizing agents, strong acids, and alkaline substances; avoid formation of dust and aerosols during handling .

1. Isolate the spill area immediately, ensure adequate ventilation, and wear full personal protective equipment including chemical-resistant gloves, safety goggles, and a suitable dust respirator .
2. Collect m-Methyl red by sweeping or vacuuming without creating dust using spark-proof and non-sparking tools, and place into suitable closed containers for disposal .
3. Avoid creating dust clouds during cleanup to prevent respiratory exposure; prevent the product from entering drains or water courses as discharge into the environment must be avoided .
4. Dispose of collected material as hazardous waste according to local, state, and federal environmental regulations, preferably through licensed chemical destruction or controlled incineration .

1. m-Methyl red CAS 20691-84-3 is not classified as highly flammable under typical fire conditions (NFPA fire rating of 0), but may decompose when heated to high temperatures.
2. Use m-Methyl red dry chemical powder, carbon dioxide, alcohol-resistant foam, or water spray to extinguish fires involving the product .
3. Firefighters should wear self-contained breathing apparatus in pressure-demand, MSHA/NIOSH approved, and full protective gear when handling burning m-methyl red due to hazardous decomposition gases generated by thermal decomposition .
4. Hazardous decomposition products formed under fire conditions include toxic fumes of carbon monoxide, carbon dioxide, and nitrogen oxides.