It depends on the composition of the volatiles and whether the concenetration is high enough for your system to detect. What is initial temperature of the GC run? If it is too high, more than one component may come as one peak.

Thanks for reply.

I am starting from 35 C. holding for 3 minutes and then with ramp of 2 C/min to 40 and then hold for 2 min. Then with 4 C/min to 180 C hold for 5 min and finally to 220 C with 10 C/min.

I am expecting 10--15 compounds. Mostly are alcohols, Ketones, Esters and some Benzenoids.

Colum is fine, but the collection time and SPME fiber may influence your result.  How long did you collect volatiles? Pink SPME fiber would be a better option for you.

Collection time is 40 minutes. 

I have pink fiber (PDMS/DVB). I can try from that fiber.

DB5-ms is a non polar column. Would it be good to separate alcohols, ketones, esters?

in my oppinion the colunm may be ok but can use other column as 624.

In that case you may try column with polar stationary phase (carbowax, or OV-225). If you know the compounds you are looking for, you can try GC/MS in SIM mode.

Thanks for the answers.

I'll have to differ with the previous answers. The column is not fine. DB-5 is a 5% diphenyl, 95% dimethyl polysiloxane that is widely used for non-polar compounds. If you want to use it for chemicals that have active polar functional groups like alcohols and esters then these have to be derivatised to non-polar derivatives first. That's why you are not seeing many compounds in your chromatograms. SInce you use SPME injection and don't seem to have a separate extraction, cleanup protocol for your samples. I suggest that you change the column to something suitable for these polar compounds. A quick look at the guide of any commercial company (e.g. Agilent, Thermo, Restek...etc) will tell you what is their column for separation of polar compounds including low molecular weight volatile alcohols. 

I am agree with Mohamed Abou-Elwafa Abdallah. Your target compounds are polar. So you should use the polar columns to get the better separation. You should opt for another column rather than derivatizing the analytes.

I analysed essential oils (liquid phase) and I had no problems. I had the same column as you. In chromatogram, I had about 50 peaks and also polar compounds like alcohols or acetates. When I sampled gas phase of essential oils, the number of peaks decreased (peaks of polar compounds lost) due to less volatility of polar compounds. So I think, the problem would be in the concentrations of gas samples.

Thanks... every comment is valuable for me.

If I rather use head-space instead of SPME, would it increase the chance of detection? My aim is to get the volatiles of healthy and fungus-infected berries.