Campesterol reference substance is a primary reference standard with certified absolute purity (considering chromatographic purity, water, residual solvents, inorganic impurities).
The reference substance campesterol always contains a certain percentage of its epimer dihydrobrassicasterol. The epimers cannot be separated chromatographically, however, the ratio between campesterol and dihydrobrassicasterol can be determined by the evaluation of the 13C-NMR spectra.
On the certificate of analysis the absolute purity values for campesterol, dihydrobrassicasterol and total sterol content (sum of campesterol and dihydrobrassicasterol) will be given. The chromatographic and absolute purity of the reference substance shown in this quotation refers to the total sterol content.
The reference substance campesterol always contains a certain percentage of its epimer dihydrobrassicasterol. The epimers cannot be separated chromatographically. However, the ratios between campesterol and dihydrobrassicasterol can be determined by the evaluation of the intensity of the respective carbon signals in the 13C-NMR spectra. From this ratio a factor is derived which is included in the calculation of the absolute purity for campesterol, dihydrobrassicasterol and the sum of both sterols.
soluble in methanol; practically insoluble in water
