I am trying to measure the concentration of a Volatile Organic Compound (VOC) inside a liquid using Gas Chromatography (GC). The liquid contains particles that cannot be sent to a GC, so I am using the head-space method (allowing the organic compound to evaporate into the gas above the liquid--- see this link:http://www.chem.agilent.com/Library/applications/5990-3285EN.pdf)--
I let the contents of the liquid equilibrate with the air in the vial at 50 C-- and then I use the air as feed for the GC. However, the concentration in the air is rather small ~ 10-20 ppm. Is there a technique that can be used to increase the concentration of the VOC's?
I have wanted to use a smaller vial to collect my liquid, but the liquid splashes about and contaminates the cap of the vial, which makes me scared to inject a needle into it as I may wreck the needle.
I tried to repeat the experiment with the vial at a higher temperature ~70 C. This lead to the needle clogging. I am unsure of the cause of the needle clogging but I suspect it may have something to do with water evaporating and taking some of the polymer particles with it. Once in the needle, the particles could get dry and solidify.