She could change columns or try the GC/MS, but there is a simpler approach. The solvent (methanol) is soluble in water while the xylenes are not. Therefore, she could use the static (equilbrium) headspace technique by injecting the sample solution into a sealed vial containing water. When the sample is mixed, the xylenes will be almost completely distributed into the vapor phase in the vial while the solvent will remain primarily in the liquid phase. The analyte to solvent ratio will therefore be considerably enhanced and it is possible that she can largely remove the solvent peak from her chromatogram by sampling the headspace (i.e., vapor phase), assuming that the dilution factor is not so great that sensitivity is compromised. If sensitivity is an issue with the FID, it may be necessary to go to the capillary column GC/MS for the analysis.

(Note: a good reference for headspace analysis is the book "Static Headspace-Gas Chromatography: Theory and Practice" by Bruno Kolb and Leslie Ettre (Wiley-VCH, 1997)

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