ChemicalName:3-[3-(2,4-Dimethylphenylcarbamoyl)-2-hydroxynaphthalen-1-ylazo]-4-hydroxybenzenesulfonic acid, sodium salt
Appearance: Dark red or dark reddish brown powder
Absorbance in 55% EtOH (0.027 mmol/l): ≥0.500 (around 605 nm)
Absorbance in 60% EtOH (0.055 mmol/l, Mg complex): ≥0.200 (around 505 nm)
MW: 513.50, C25H20N3NaO6S
Storage Condition: ambient temperature
Shipping Condition: ambient temperature
XB-I is a colorimetric reagent for Mg detection. It is slightly soluble in water and alcohol, and readily soluble in aqueous alkaline solution. The aqueous solution of XB-1 is red, and turns reddish-violet in the presence of Mg at pH 9 (maximum wavelength: 510 nm, molar absorptivity: 49,000, detection range 0.02-0.4 ppm).
C. K. Mann, et al., Spectrophotometric Determination of Magnesium with 1-Azo-2-hydroxy-3-(2,4-dimethylcarboxanilido)naphthalene-1 E(2-hydroxybenzene). Anal Chim Acta. 1957;16:155-160.