spirit blue spirit blue spirit blue or opal blue ss is a dye with formula c37h30cln3. it is used as an indicator in agar for detection of lipase activity in bacteria. spirit blue names iupac name 4--n-phenylaniline hydrochloride other names opal blue ss, hsdb 466, solvent blue 23 monohydrochloride identifiers cas number 2152-64-9 y chebi chebi:86483 y chemspider 15674 y echa infocard 100.016.766 pubchem cid 16534 unii 690do205ax y comptox dashboard (epa) dtxsid3027457 properties chemical formula c37h30cln3 molar mass 552.12 g·mol−1 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references