(1,5-Diphenylthiocarbazone)  C13H12N4S M.W. 256.32 Assay min 98.0% Specific Absorptivity at 605nm min 1522 Relative absorbtion (A 605 nm/at 445 nm; chloroform) min 2.5 Sulphated ash max. 0.2% Heavy metals (Pb) max. 0.001% (Reagent for lead, mercury and zinc)