The method that suits your sample preparation must be used. Otherwise LOD LOQ precision and total time are suitable. For me gc with internal standard is better and quick.

for the analysis of oxyfluorfen in natural water , gas chromotographic  technique is widely used and results are accepted by repute journals.

You should be able to request a copy of the method submitted by the manufacturer to the Office of Pesticide Programs, US EPA.

Thank you all for your answers.