detection of unknown peaks in Gas Chromatography

[a s reddy]

situation is regular analysis is done for Natural Gas and by some other reason if an unknown componant is ingressed in to the sample, how can it be detected? are there any methods avilable..........

[Don_Hilton]

If it was totally unknown, you may have to try a number of methods. First step: understand the sample. What is the source of the contaminant and what concentration range are we looking for? Give as much detail as you can about the problem. This may help to narrow down possibilities.

Given that this is a component in a gas sample, GC seems like a good choice. If the contaminant is likely to be an organic compund -GC-FID may detect it. But, wihtout any clues as to what the contaminant may be, even this is a guessing game.

[chromatographer1]

Generally NG analysis is done with a TCD which responds to almost everything.

Generally NG analysis is done with a reverse column step (backflush to detector) which sends any analyte larger than C6 to the detector. So nothing volatile should be missed in the analysis.

About the only volatile analyte that may be missed at low levels is water vapor, but in larger concentrations even it should be detected.

Your general question is difficult to answer comprehensively with so little detail offered. Do you wish to discuss? Please give a lot more details than you have so far.

best wishes,

Rod

[Bricevan]

Sorry to make an off-topic post.

Rod please contact me at bricevan -at- wasson-ece.com. We would like to solicit your help regarding a special packed column phase. Thank you.

[chromatographer1]

Brice,

My contact information is in my profile.

Rod

[a s reddy]

If it was totally unknown, you may have to try a number of methods. First step: understand the sample. What is the source of the contaminant and what concentration range are we looking for? Give as much detail as you can about the problem. This may help to narrow down possibilities.

Given that this is a component in a gas sample, GC seems like a good choice. If the contaminant is likely to be an organic compund -GC-FID may detect it. But, wihtout any clues as to what the contaminant may be, even this is a guessing game.

" dear Sir,
this was the question i was posed in an interview. it was told that there are two methods by which the unkonown companat will be detected.to my best of knowledge it is guessing game and FID will give some clue even that too if you know the what will be the contaminant..."

[Don_Hilton]

Interview questions have many agendas hidden behind them. One is to see if your knowledge of the field is sufficient to do the job. Another is to see how well you can handle a problem. You may be asked a question that does not really have an answer - just to test your analytical skills in getting to the solution of the problem. (Or, will the canidate try to bluster his/her way through the answer to the unanswerable question.)

And if you were given only the detail that you have passed on, the interviewer may have been looking to see what addtional information you would seek to obtain about the sample before selecting an analytical method.

Some of this will depend on where this question fits in the context of the whole interview.