Content Handbook J
Outline of method
Fenoxaprop-ethyl is a racemic mixture, containing equal amounts of fenoxaprop-P-ethyl (R-enantiomer) and fenoxaprop-M-ethyl (S-enantiomer). Hence two methods are used to determine the chemical and the enantiomeric purity.
The first analytical procedure determines the fenoxaprop content of the sample and the method determines the sum of both enantiomers. This method may also be used for the determination fenoxaprop racemic mixtures. The active ingredient is determined by normal phase HPLC using a silica stationary phase and gradient elution, UV detection and external standardisation.
The second part describes the determination of the enantiomeric purity. Fenoxaprop-P-ethyl is separated on a chiral phase (mobile phase isooctane: propan-2-ol-trifluoroacetic acid) from the other enantiomer and the enantiomeric ratio is determined using UV detection.
The method is usable for TC and EW-formulations.