I have already used my GC vials to perform an experiment in GC ion trap and hence i want to reuse the GC vials again. Is it safe and possible to reuse it?
You can reuse your GC vial but you should make sure that your vial have high quality doesn't eco-grade. you can wash them by use your solvent which you use and do not use ultra sonic.
If you have plans to reuse GC vials it would be a good idea to look into using GC vial inserts. They are generally cheaper than the vials, require less sample, and create a smaller volume of waste when disposing of them. There is also the additional advantage of not having a volume of GC vial washing solvent you now have to dispose of safely.
Even with inserts it is still important to run a blank every few injections in a sequence to confirm there is no carry over contamination.
If the vials you are using are a screw cap type, do not reuse the caps of these vials.
And, in cases where your analyte concentrations are expected to be either very high or at trace level I would always splurge on a new GC vial. Your labor of re-running those samples will cost more in time, materials, and energy than vial recycling would save.