A NEW PARAMETER FOR CHECKING THE SUITABILITY OF ALPHA-TOCOPHEROL STANDARDS

The quality of an a-tocopherol standard can be checked easily by measu ring the UV absorbance at minimum (255 nm, A(min)) and maximum (292 nm , A(max)) wavelengths in n-hexane. If the quotient A(min)/A(max) excee ds 0.18, the standard contains less than 90% alpha-tocopherol and the determination at 292 nm will yield inaccurate results.