This all depends on what SPME fiber phase it is and how the fiber was used.  Refer to the Solid Phase Microextraction Troubleshooting Guide, see link.

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Supelco/General_Information/1/t101928.pdf

Hello Sagarika - SPME fibers are reusable and it can be used multiple times. I would like to add to previous comments that SPME can also extract while in storage or while in-between extractions.  Thus, it is a good idea to check this (by analyzing SPME after typical storage conditions or after typical waiting times.  Air in the lab, air in the storage can be contaminated.  Thus, it is recommended that SPME fibers are desorbed immediately before extractions, if there is a concern that they might be exposed to interfering compounds. 

One strategy that worked for us, especially for field applications, is to fold a clean (baked out) aluminum foil around SPME assemblies (to the point that it looks like a flat bubble gum wrapping), pressing out air out of it and folding and creasing the ends.  Such an isolated SPME can be stored in a clean sealed jar for transportation to/from field.  This could also be used to store SPME in a generally dirty/unknown environment. 

In the past, we also used Teflon plugs to seal the very tip of SPME needle.  They were made from 1/4 inch section of Teflon rod with bored ~0.5 mm hole for needle insertion.  We described it in:

Koziel, J.A. and J. Pawliszyn. 2001. Air sampling and analysis of VOCs with solid phase microextraction. Journal of the Air & Waste Management Association. 51, 173-184.

I hope it helps,

Jacek

The stability and re-usability of the fibre depends also on desorption temperature and on the matrix. According to our experience the stability depends on:  head space >water>polluted water>biological fluids

Thank you Bruce , Mohamed Abdel-Rehim, Jacek , Hilal and Jan   for you answers. I really appreciate your help.

Our experience with plant material as sample is that you can use a PDMS/DVB/CAR fiber up to 1000 times. PDMS fiber with wine several 100 times. We monitored the performance with internal standard or control samples.

Thanks Georg. Can you tell me how long were you able to store it before discarding it? I mean for how long can I use it after the first use?

See also earlier question and answers:

https://www.researchgate.net/post/How_many_time_we_can_use_one_SPME_fiber_assembly