Help. about gas chromatography?

why when i run gc for (standard) dha methyl ester identification, there is no peak at all? help.
i use semi polar column for other standard (EPA and ALA) with IT= 70 oC and FT=265 oc? i've no idea what to do.. i've check web site and no solution. :"(

Answer:
I think your oven parameters are probably OK. DHA Me ester's BP is ca 300C, so your range is probably OK, or if anything, a bit low. Has this method worked in the past?

Also, are you sure your detector is working? Is it an FID? Is the flame lit? Are you getting a signal from the detector?

Is your carrier gas turned on and the flow rate set correctly?

Are you manually injecting or using an autosampler? Are you sure a sample is actually being injected by the autosampler? Is the injector needle plugged, and not drawing any sample?
hmmm..what´s the b.p. of the DHA methyl ester? it might be that if it is too low, and the compound is pretty volatile, it comes together with your solvent peak. just reduce the starting temp and the flow of Ar, i would say, see if it comes out.

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