As Dodeca 2E,4E,8Z,10E,Z-tetraenoic acid isobutylamide reference substance occurs as a mixture of two isomers (10E and 10Z) the absolute purity is assigned by quantitative NMR . These show differences in UV absorbance, are poorly resolved in HPLC, and peak areas differ. Isomer composition may also vary between different batches. Thus, batch to batch continuity cannot be proven by HPLC-UV. Even if absolute purity of two batches is identical, the peak areas obtained in HPLC can differ significantly. If the isomer composition of the analyzed sample differs, then additional uncertainty will be introduced. For these reasons we strongly recommend to use this reference standard for qualitative purposes only and to be aware of the analytical challenges. Nonetheless, we provide quantitative data and a certified purity value on the COA. More detailed information will be given on the documents accompanying this reference substance.

来源	Echinacea sp.
归类	Nitrogen-containing Compounds