ERIOCHROME BLACK T ACS GRADE excellent quality manufacturer , exporter and supplier. Eriochrome Black T, Reagent, ACS, also known as Solochrome Black T, is a complexometric indicator used as an indicator in EDTA titration. As an ACS grade quality reagent, its chemical specifications are the de facto standards for chemicals used in many high-purity applications and typically designate the highest quality chemical available for laboratory use.