Your question asked if there were OTHER methods which did not involve GC or HPLC, so my suggestion is to focus on the different chemical or physical properties of the two samples to find a method to measure them. RI, IR, viscosity, density and so on.

GC/MS is by far the best, however, if unavailable, there are other ways...

if you add a mass spectrometer to a GC setup as GC-MS, this should give you very high sensitivity and selectivity for volatile compounds

Your question asked if there were OTHER methods which did not involve GC or HPLC, so my suggestion is to focus on the different chemical or physical properties of the two samples to find a method to measure them. RI, IR, viscosity, density and so on.

GC/MS is by far the best, however, if unavailable, there are other ways...

Thank you so much for your valuable suggestions @Stefanie Maedler ,

@Noel W Davies , @William Letter

GC or GC-MS is the most convenient and efficient method, is easy to get in any Chemistry Department. Alternative method should be chemical analysis and hard to perform for all volatile once.

Ananya,

Purge and Trap GC/MS is the traditional method (I assume you're talking about liquids and not solids) for getting VOCs out of drinking water/waste water. If it's in a solid matrix then a Head Space analyzer hooked up to the injector line on a GC/MS is the method of choice.-Paul D. Dodson

Thank you @Jian-Xu Zhang and @Paul Dodson for your valuable suggestions.

Dear Aranya, it would be good to know more specific details, for example, is the sample solid? Is there an idea of the composition interval of the two volatile compounds? Are the interactions between the two volatile compounds and the solid matrix different? If it is a solid sample and the percentage of volatiles is important, you could consider using a thermogravimetric analysis technique. With a preliminary thermogram, the feasibility of moving forward with this idea could be evaluated.