Alcians blue carries Phthalocyanine one of the most highly colored chromophores yet known with a molar extinction of 120,000 i.e. AB is detectable at half the molar concentration of popular dyes like toluidine blue, tryarylmethanes (e.g. pararosaniline and the analogous Schiff bases used in PAS stain, Crystal violet in Gram stain) etc.
They have reduced chloride sensitivity, faster maturation, and increased brightness (defined as the product of the extinction coefficient and quantum yield).
Molar absorptivity | Molar teeth of ''T. punjabensis'' at the Museo Civico di Storia Naturale di Verona, Verona | Kirchhoff's law of equality of radiative emissivity and absorptivity |
The Tollens’ test for pentoses relies on reaction of the furfural with phloroglucinol to produce a colored compound with high molar absorptivity.