Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 50-27-1, Whether you call it Estriol, (16alpha -17Beta)-Estra-1 -3 -5(10)-triene-3 -16 -17-triol , Follicular Hormone - Hydrate or Oestriol you can be assured the Estriol products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.