I am going to work on vitamin E ( α-Tocopherol, g-Tocopherol) analysis by RP-HPLC with UV detector.
Svereal papers states that vitamin E working standards are prepared and corrected daily according to their absorbance values E (1 cm/1%) α-tocopherol 75.8 at 292 nm , γ-tocopherol 92.8 at 298 nm, δ-tocopherol 91.2 at 298 nm.

Why? Is this necessary? Do we have to correct it daily?


Thank you