GC question

Chromatography Forum: GC Archives: GC question
Top of pagePrevious messageNext messageBottom of pageLink to this message  By nathan on Monday, December 17, 2001 - 07:19 pm:

Which of these cannot be analyzed by GC?

xylene
naphthalene
nitric acid
tetrachloroethylene


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, December 18, 2001 - 01:41 am:

Somebody thinks that this is a e-net school !!!
Try thinking about the diffeences between all this compounds and then choose the correct answer !!!
It's a piece of cake !!


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, December 18, 2001 - 05:22 am:

You can tell when it's the end of the semester and all the homework questions appear.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, December 19, 2001 - 05:12 pm:

Nathan,

In response to your inquiry, I am not going to make a flippant statement regarding your question nor make ungrounded assumptions about your motivations for asking the question. Instead, I am going to trust that you have a worthwhile and above board need for the information and try my best to give you a serious answer. I thought that was the whole idea of a forum such as this. It does not seem right that one must justify their need for information before it is given on this forum. I have no evidence that you are trying to cheat on a homework assignment. You may be, but I am willing to give you the benefit of the doubt and assume that you are not.

Now, to answer your question. I am new to GC myself so please take this with a grain of salt and follow up with other sources. All of the compounds are volatile and thus at first glance should be GC-able. However, you will notice that nitric acid stands out like a sore thumb -- it is the only acid in the group and it is the only inorganic compound in the group. Acids do not elute well from GC columns and usually must be derivatized to gain any appreciable amount of retention. Also, the inorganic nitric acid is not amenable to the most common detection techniques. Therefore, I believe that nitric acid is the compound that cannot be analyzed by GC.

Again, I am not completely sure of this. It would be good if a more experienced chromatographer could answer this question definitively. I am curious myself and I promise, I am not a student trying to cheat on a homework assignment. If you need the proof, I will fax you a copy of my B.S. degree.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, December 20, 2001 - 06:29 am:

Dear Anonymous,

Generally when the questions are simple ones that can be answereed by opening any basic reference the assumption is made that the person posting the question is trying to complete an assignment in the easiest possible manner. This may not be true, but more often than not it is. Sorry if you are offended by others who are tired of seeing this. One of the big clues is a question like the original posting that does not start out "I am trying to do ..." or "I am having trouble with ...".

Also, having a B.S. degree does not mean you are not a student trying to cheat on a homework assigment.

In answer to the original posting, all can be analyzed by GC, but only three commonly are. There are many better, easier ways to do nitric acid.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Fred on Thursday, May 2, 2002 - 07:01 am:

Nitric acid cannot be analysed by GC. If anybody does please give me the column specification and GC conditions.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, May 2, 2002 - 10:14 am:

Hmmm, that's an interesting speculation. Nitric acid = HNO2, BP 83C. So why can't it be analysed by GC? Okay, it chews up any real column. But maybe you could fill a glass column with silica and get a separation (from what?) on that. Detection - it chews up the detector. Minor details! After all, you wouldn't actually inject much of the stuff. Maybe an electrolytic conductivity detector? Maybe just conductivity without elecrolysis. Have to read up on that again.
Oh, well, back to work.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By What's your Name on Saturday, May 18, 2002 - 07:54 am:

The chemical formula is HNO3, Nathan! Don't believe these guys, man. They are pulling your leg. Actually, I can tell you what you should do.

Think hard and choose the correct answer...

Nathan, Hey nathan....He is gone...

PS: Why are all your well wishers anonymous, Nathan.


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