gas chromatography

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choudary's picture
gas chromatography

  i am rajesh, 

im trying to do some biodegradation experiment which invloves extraction and estimation of some hydrocarbons.
my problem is i am getting inconsistent readings in gas chromatography, ideally the hycrocarbon amount shoud decrease with time as per my experment, i am using internal standard (naphthalene) . say for example the paek area of napthalene and hexadecane are 100 and 150 at 0 hours but with extraction of 24 hours sample is coming like 200 and 400. if there is problem with extraction of hexadecane atleast the intenal standard i.e., napthalene peak should reamin stable around 100 though out the experiment. is it because of  error in volume going into the GC or any problem with other parts like detector.

program: 50 to 2500c  at the rate of 5 0c .   injector temp = 2400c   detector (fid) = 2500c.

please help me.