Ferula narthax bioss - How to measure the purity by GC/HPLC?

Dear Sir,

I are working on medical plant ASAFOETIDA / Hing (Ferula Narthanx). Different kind of adulternts are added in this product htat available in rock and powder.
Can any body help me in guiding on checking purity measurement and quantification on it as finish produict.
Aslo please suggest which technique will be suitable GC-FID ,HPLC and it set up.
Thanks
harendra

Can anyone assist Harendra with this?

Regards,
Simon