S 2609 (OTTO) Stigmasterol, 95% Cas 83-48-7 - used as the precursor of vitamin D3. S 2609 (OTTO) Stigmasterol, 95% Cas 83-48-7 - used as a reference standard in determination of phytosterols in dietary supplements by gas chromatography and in frozen leaf samples of Arabidopsis thaliana by GC/MS.