Arsenazo III 

Arsenazo III is an azo derivative of chromotropic acid, a metal chrome dye, a chelating agent, and a cation complexing agent. Arsenazo III forms stable 1:1 complexes with Ca²⁺, Mg²⁺, Sr²⁺, Ba²⁺, K⁺, and Na⁺, and its binding affinity for Ca²⁺ depends on pH, alkali metal cation concentration, and buffer parameters. Arsenazo III serves as a colorimetric indicator for micromolar ionized Ca²⁺ in cells^[1][2].

Arsenazo III (0.74-193000 μM) forms stable, spectrally distinct complexes with alkaline earth metal ions (Ca²⁺ > Sr²⁺ > Ba²⁺) and K⁺ in buffered aqueous solutions, with a Ca-dye dissociation constant of 0.74 μM at pH 7.4 under low-ionic-strength conditions, and measurable changes in absorbance that enable quantitative determination of free Ca²⁺ concentrations^[1].
Arsenazo III (30-40 μM; 20°C, pH 7.0, 7.4, or 7.6) has an apparent calcium binding affinity that depends on buffer type and concentration, decreasing with increasing buffer concentration and varying across imidazole-Cl, K-Hepes, and Tris-Cl at the same concentration and pH^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

776.37

C₂₂H₁₈As₂N₄O₁₄S₂

1668-00-4

Solid

Brown to black

560

530

O=S(C1=C(/N=N/C2=CC=CC=C2[As](O)(O)=O)C(O)=C3C(O)=C(/N=N/C4=CC=CC=C4[As](O)(O)=O)C(S(=O)(O)=O)=CC3=C1)(O)=O

Room temperature in continental US; may vary elsewhere.

4°C, protect from light

*In solvent : -80°C, 6 months; -20°C, 1 month (protect from light)

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month (protect from light). When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

• [1]. HY-D0202-1.pdf  [Content Brief]

  [2]. HY-D0202.pdf  [Content Brief]