I already tried the standard solutions and tried to inject directly to the GC, but I did not get good results. Any ideas?
Can you give some more details? What did you do exactly and what do you mean with 'not so good
first tried to get calibration curve by external standard and i did it with direct injection of my standard solutions to the GC, but didn't get linear calibration curve!
after that i choose internal standard method for calibration, unfortunately got deviation more than 2% for my results!
Gc seems to be a simple straight forward technique, at least at first sight. There are plenty of opportunities for trouble.
The liner needs to be compatible with the solvent, the injected amount and of coarse with the analyte. The column and temperature regime for the hole system needs to be optimized for the job at hand, if the peak of interest is not pure quantification will be a nightmare. The fid is the best part in the system, it is in my opinion the most robust detector avaible..
You could first try to run a reference methode to rule out equipment problems, then switch to a standard application for your column using an easy solvent like hexane or so. Change one parameter at the time to arrive at your final application.
Have a critical look at the calibration curve's, pass trough zero?, completely linear or only at low concentrations (could be overloading). Don't trust your judgment on linearity, have a look at the residuals.
Before You will start calibration procedure, check Your GC instrument. Check if the column is apropriate to the solution used to the calibration, check the flows of gases, temperatures of injector, column, detector, check possible leaks of gases and if You are sure the GC instrument is ready to analysis start with calibration procedure.
i agree with Euzebuisz D. but after you have done all the physical check to be sure,some system actually comes with " system check'' which can be performed,if all the components PASS this test...then you ensure to use the right column, standards and begin your calibration
I would like to know the calibrbration of detector.Perhaps all of u guys have suggested the procedure of calibration with respect to sample being analysed.It would give of course correct analysis for the sample in question.However,so far I remember people do calibration for the detector type used in GC.At present I donot remember that.Can anybody suggest.
Hi Amritanshu Kumar, Yes you are right. We stated as regards to samples been analysed, but if you look at my response I draw you attention to system check. Detector Calibration is something that can be done once in six months depending on the frequency of use. And you may want to do so if you observe there is no consistency in the results, or change in response in other cases you may need to perform simple routine maintenance like for GID cleaning the jet .
The detector are usually calibrated at the point of installation. But you can check the link below for a simple FID calibration procedure. I hope this helps. https://www.pharmaguideline.com/2010/11/gc-calibration.html?m=1
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