GC/MS analyses can be carried out on a Shimadzu GC‑MS‑QP2010 apparatus equipped with a ‑5 column (60 m × 0.25 mm i. d., film thickness of 0.25 µm). Helium can be used as carrier gas at a constant column flow 1.2 ml/min at 173 kpa inlet pressure and injector volume was 1.0 µL. The test run can be performed according to a set temperature programming, which is  maintained from 100°C to 200°C with constant rise of 5°C/min and then held isothermal at 200°C for 6 min. Further, the temperature get  increased by 10°C/min up to 290°C and again held isothermal at 290°C for 10 min. The injector and ion source temperatures should keep  270°C and 250°C, respectively. The crude and active bands (AB‑1) and (AB‑2) (2 mg/ml) can be dissolved in methanol (HPLC grade, Merck, India) and are injected with a split ratio of 1:10. Mass spectra were taken at 70 eV; a scan interval of 0.5 s and fragments from 40 to 950 Dalton. The identification of  natural product components can be done  based on the comparisonof their relative retention time (tR) and mass spectra with those of commercial standards (for the main components) and on the gas chromatography (GC) retention indices (RI) determined relative to n‑alkanes (C8-C32). The final confirmation of constituents can be made by computer matching of the mass spectra of peaks with the Wiley and National Institute Standard and Technology (NIST) libraries mass‑spectral database. For sampling in injection port you will need 5-10 microlitere volume, if you want for extraction purpose, you should 

You could also used “headspace SPME”, for the PAH extraction from your solution. In this case, you do not introduce the SPME fiber in the solution but simply expose it in the headspace of your closed system for a certain amount of time (~1h). The PAHs will equilibrate between the air and the water phase and get adsorbed in your SPME. Then you do a thermal desorption in your GC/MS

We have been using SPME for PAH extraction. It strongly depends on which compounds are you aiming for. With headspace SPME you only aim for the low MW ones, which by the way are considered to have a lower carcinogenic potential. We did not succeeded in extracting anything above the MW of Pyrene (202) by using headspace SPME (PDMS 100microm). Perhaps another PDMS fiber with a thiner stationary phase could aim for a bit higher MW, but I do not think so.

https://www.researchgate.net/publication/23652275_Analysis_of_polycyclic_aromatic_hydrocarbons_in_solid_matrixes_by_solid-phase_microextraction_coupled_to_a_direct_extraction_device

Temperature and time conditions should be optimized. For higher MW compounds the different equilibria during the extraction take longer.

If you carry out the extraction by immersion, PDMS is definitively the best phase for PAH. Beware of the amount of solvent (hexane will dissolve the stationary phase of the fiber). The volume it takes from the solution  is almost negligible.

Article Analysis of polycyclic aromatic hydrocarbons in solid matrix...

Thanks all,  

I am using Thermo brand GC/ MS and  SPME, Supelco Brand and I am carrying out the extraction by immersing the Fiber in water. In the analysis of SPME standards I got a Huge Peaks of PAHs in comparison with the standards of the analysis of PAH in Dichloromethane ( normal analysis) for example the 100ppb (SPME) gave me 24 ppm based on liquid hydrocarbon analysis curve and Dr Jorge Ruiz Carrascal says "The volume it takes from the solution is almost negligible." 

You're absolutely right. I mixed up with the headspace: the recoveries by immersion, specially with PDMS and for the high MW PAHs can be 100%. There is a nice and easy explanation in this tutorial:

http://www.gerstel.com/pdf/p-gc-an-2001-08.pdf

Sorry for the wrong explanation 

It seems that the discussion is very interesting 

actually, I carried out the standard analysis as a normal analysis (0.1 micro L, Split-less option) from PAH-Dichloromethane solution. is that means the fiber of SPME takes more than 0.1 micro L and gives me this high concentration  and then I should carry the quantitative on  a new standards based on the SPME analysis  and the question still presents itself ; Does this have any effect on the sensitivity of Mas spectrum or not??Jorge Ruiz CarrascalJavier Castro-Jiménez

Dear Ahmed,

You said you injected 0.1 micro L in your GC/MS?. This volume is very small, normal injections are 1 micro L. Which are the PAHs you want to quantify?. I would also suggest preparing your standard solutions in hexane (if your target PAHS dissolve well) because is better solvent than DCM for CG analysis.

First, you have to consider the concentration you have in your standard solution to calculate how much PAH is actually extracting the SPME. For sure that all PAHS together do not sum up 0.1microL. As you could see in the link I included in my previous answer, it can be almost 100% . 

As for the effect on sensitivity, for sure, it has. AS any other detector, above a certain concentration you do not have any longer a linar response. And on top of that, the life of the MS will be very much shortened with this huge peaks.