ChemicalName: Mixture of ammonium purpurate and potassium sulfate
Appearance: Pink or reddish purple powder
Absorbance: 0.150 E0.200 (at 525 nm)
Sensitivity: pass test
Storage Condition: ambient temperature, protect from metal
Shipping Condition: ambient temperature
MX is a 1:250 mixture of Murexide and potassium sulfate. Murexide is a metal indicator for Ca, Co, Cu, Ni, Th, and rare earth metals; it is also a colorimetric reagent for calcium and rare earth metals. Murexide is slightly soluble in water, alcohol, and ether. Murexide is unstable in aqueous solution. Its proton dissociation constants are reported to bepKa1=0, pKa2=9.2 and pKa3=10.5. The solution is yellow in strong acidic conditions, reddish-purple in weak acidic conditions, and bluepurple in alkaline conditions. Detection conditions for calcium are pH 11.3, maximum wavelength 506 nm and detection range 0.2-1.2 ppm.
K. S. Balaji, et al., Anal. Chem., 50, 1972 (1978).