The concept of pH, measuring the acidity or alkalinity of a solution, is fundamental across numerous scientific disciplines. pH indicators are indispensable tools that provide a visual means to gauge these levels. Among the most recognized and widely used is Phenol Red (CAS: 143-74-8), a chemical compound whose color-changing properties are leveraged extensively in laboratories and industries.

Phenol Red, a member of the sulfonphthalein family of dyes, operates on the principle of acid-base equilibrium. Its molecular structure undergoes reversible changes as it gains or loses protons in response to the surrounding solution's pH. At low pH values (acidic), it exists in a protonated form, absorbing light in a way that makes the solution appear yellow. As the pH rises, it loses protons, transitioning to a quinoid structure which absorbs light differently, resulting in a red color in the neutral to slightly alkaline range. Further increase in pH (alkaline conditions) leads to another deprotonation, yielding a highly conjugated system that absorbs light at longer wavelengths, giving the solution a distinct bright pink or fuchsia hue.

The specific pH range where these color changes occur is critical for its application. Phenol Red typically exhibits its full color change between pH 6.8 (yellow) and 8.4 (red/pink). This range makes it particularly useful for monitoring biological systems, which often operate near neutral pH. Its applications are varied: in cell culture, it signals changes in metabolic activity; in microbiology, it aids in identifying bacteria based on their fermentation pathways; and in analytical chemistry, it serves as an endpoint indicator for titrations where the equivalence point falls within its transition range.

For those looking to procure this essential reagent, understanding its source is vital. NINGBO INNO PHARMCHEM CO.,LTD., a reputable chemical manufacturer and supplier based in China, offers high-quality Phenol Red (CAS: 143-74-8) that adheres to strict purity specifications. We provide a reliable supply chain, competitive pricing, and excellent customer service, ensuring that researchers and industries worldwide have access to a consistent and dependable product for their critical analytical needs. Whether you need to buy Phenol Red for research, diagnostics, or industrial applications, our commitment to quality makes us your ideal partner.