Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 3326-32-7, Whether you call it Fluorescein Isothiocyanate, Isomer I, FITC or Fluorescein 5-Isothiocyanate you can be assured the Fluorescein Isothiocyanate, Isomer I products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.