By Kati on Thursday, December 26, 2002 - 03:49 am:

I have been working with HPLC for a few years but I have no experience in GC. Is there any basic literature of GC theory and how it works, as Snyder & Kirkland in HPLC?
Are there any "practical GC method development" courses equivalent for the HPLC courses?
Thank you the answers in forward!

Kati

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By Anonymous on Thursday, December 26, 2002 - 01:10 pm:

I am assuming that are now or soon will be operating a GC. Most manufacturers offer courses similar to what I think you are interested in. Also, Restek (a manufacturer of GC and HPLC columns) offers a seminar that gives a general overview in GC theory. This seminar travels around the country or they can come to you. Their website is www.restekcorp.com . Hope this helps.

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By siva on Sunday, March 2, 2003 - 11:18 pm:

I have been working with GC for a few years but i have facing problem with estimation acetic acid content LOQ/LOD. It is very difficult to get the cosistency results with respect to system to system and column to column.

So, please clarify any theoretical background is there.

Thank you the answers in forward

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By Anonymous on Monday, March 3, 2003 - 05:27 am:

One excellent way of determining Acetic acid content is with NMR spectroscopy.

My NMR experts have told me that it was too difficult until they actually tried it.

Boy, were they surprised.

Acetic acid at low levels is very sensitive to slight changes in matrix and injector-column-detector conditions.

Titration or NMR are better analytical techniques for trace amounts.

Rodney George

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By Haslina on Friday, April 4, 2003 - 12:55 am:

I am doing research in production of ethanol in water standard.I'm using GC-FID for this purpose.My problem is, I did't get a consistence result everytime I run the sample. I also don't know the best column temperature for this sample.I also obtained a not nice peak shape;tailing and broadening. Can you help me solve this problem?

Thank you in advance.

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By Anonymous on Friday, April 4, 2003 - 05:42 am:

There are many methods in the literature for this ancient application. Go to any GC column manufacturer web site and look for yourself.
You can use packed colums or capillary columns.
You do not tell anything about what you are doing except you are using FID. How can this community help you correct what you are presently doing unless you give us more information?
Help us help you, please, in any future postings.

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By lina on Sunday, April 6, 2003 - 08:52 pm:

Sorry for not giving you an enough information.I'm doing a research in production of ethanol in water.Before I produce the standard, I need to validate my analysis method.I verify the standard using the method below but the value I get giving a big difference with the standard value.I'm using GC-FID with capillary column.I used Methyl Ethyl Ketone as an internal standard.My instrument setup for the analysis is below;
Split ratio: 100:1
Injector temperature: 250°C
Oven temp: Int 70°C Hold 1 min
Final 120°C Hold 1 min
Carrier gas flow: 2 ml/min
Detector temp: 230°C
I hope you can give a correction and advice regarding my method.

Thank you for your time and do ask me if the information is insufficient.

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By Anonymous on Monday, April 7, 2003 - 06:41 am:

What kind of injection liner are you using? How much are you injecting? Do you have enough expansion volume in the injector to handle the size of your injection? Are you getting high or low results for your standard? Are you using the proper FID response correction factors for your analytes? Have you tried to inject a smaller amount? Have you tried to lower the injection temperature to 125°C to reduce carrier solvent expansion and possible degradation of the alcohol? Are you using slow or fast injection technique? Manual or autosampler injection? Have you changed your septa? Have you verified you have no leaks in your system and that the spitter is operating consistently?

Good luck

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By column826 on Thursday, May 29, 2003 - 06:00 pm:

Water has one of the largest vapor volumes of the common laboratory solvents. For water injections, the injector liner may be too small to accommodate the vaporized mixture, so the excess vapor will "backflash" outside of the injection port. This vapor mixture condenses on cooler surfaces resulting in a loss of sample. In the case of water, losses can be minimized by setting the injection port temperature to between 150 and 220°C (lowering the expansion volume) or using a smaller injection volume.

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By Anonymous on Friday, September 12, 2003 - 10:13 pm:

hello sir i want gc theory and literature

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By Michelle on Tuesday, December 23, 2003 - 03:25 pm:

I need to analyse nitrogen gas. I tried using GC with a TCD detector and helium as the carrier gas. Currently I am not getting any peaks. I detected leaks in the gas line, and fix those, still no peaks. I suspect that may have caused some damage in the column. However I am not sure where to start troubleshooting to confirm my suspicions. Or could I be using incorrect settings? Please advise.

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By Rodney on Monday, December 29, 2003 - 06:43 am:

Are you certain you have a working detector?

If you double your flow rate of carrier you should see a change in baseline signal, do you?

Be certain you are balanced with your reference cell. A little more information is helpful for those who would like to help you, GC model, type of TCD: Gow-Mac or Agilent, thermister or hot wire, sample size injected, etc.

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rgeorge@sial.com

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By Michelle on Sunday, January 4, 2004 - 08:30 pm:

Re the message posted Dec 23, here are some more information. I am using a HP5890A series GC with an Agilent detector.
Sample size = 10uL
Detector temp. = 180
Injector temp = 50
Oven temp = 50
Carrier flow rate = 30 mL/min
Gases analysed = nitrogen,oxygen, carbon dioxide
Carrier gas = Helium (lab grade 99.9999%)

I checked both the detector and the filament and they seem to be fine.

Hope this added information will help you advice me accordingly

Thank you for your help

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By Anonymous on Monday, January 5, 2004 - 04:59 am:

How did you check your detector and filament?

What voltage signal do you see?

Is the detector turned ON?

Sorry if these seem childish questions, but assuming your detector is working correctly, to not have any peaks means you are not really injecting sample onto the column, or the column is not connected to the detector, or there is a huge leak in your system.

Basic trouble shooting procedures found in your GC manual should be followed.

I hope you are using a suitable column and that your hardware is working correctly.

Best wishes,

Rodney George

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By Michelle on Wednesday, January 7, 2004 - 11:07 am:

For some strange reason, I seem to be getting peaks now when I just inject air. However, oxygen and nitrogen isn't separated. There's just one big peak. I checked the column that's there and it's a chromosorb type column....as you said seems as though this isn't a suitable type for the analysis I want to do. Looking at the catalog, carboxen seems to be more suitable.

Do you have any other recommendations? And can you share any reason as to why there was no peaks and now there are peaks?

Thanks again for your help

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By Anonymous on Thursday, January 8, 2004 - 08:01 am:

Chromosorb W (G or P or A either) ie Diatomaceous earth will not separate fixed gases.

Molecular sieve (5A or 13X) or Carboxen 1000/1004 will separate oxygen nitrogen.

Inexpensive, rugged, durable? Buy a simple packed steel or glass column, or micropacked column.

Why is the detector now working? Did you have a huge signal coming off the detector originally?

I suspect (sorry, Michelle) it is operator error.

If you will have carbon dioxide or other larger molecule components in your sample use the 13X packing instead of 5A.

Remember that you have to condition the mole sieve column to remove trapped water etc so the gas solid separation mechanism will be most effective.

Best wishes

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By S MOREAU on Monday, March 15, 2004 - 12:45 pm:

Dear M. HINSHAW,

I'm always interested by your articles in LCGC. But recently, I was surprised by the lack of precision when speaking of fast & comprehensive
GC & GCMS. In an article in LCGC (2002), you demonstrated the importance of the filter time
constant for GC detectors when using fast or ultrafast columns. In your last articles speaking
about such techniques, no comment was made on this parameter ... We know that no apparatus on
the market except the GC2010 from SHIMADZU has a variable value of the filter time constant. So,
what is your opinion about all the publication on
comprehensive GCxGC ?

Sincerely,

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By dromos on Monday, May 17, 2004 - 05:00 am:

Hi, I want to learn which type of columns(type,size, packing,etc.) should use to analyze diamines in GC. please help me.

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By Anonymous on Tuesday, June 1, 2004 - 02:30 pm:

A new technology of gas chromatography with pressure programming of the carrier gas has been investigated and for the first in the world been proposed, based on the gradient pressure movement along the column performing the function pressure - location - time and keeping Dp constant at the ends of the chromatographic column during the whole process of analysis.
( Russia patent N 1658083 Chromatograph of A.S.Hayrapetyan )

Provision of optional conditions by means of keeping the constancy of the linear rate of an imaginary point - the sample zone undergoing analysis being transferred from the injection point to the chromatographic column outlet, with which a maximum column efficiency /Hayrapetyan's Effect/ is attained. Inventor Hairapetian A.

CHROMAB A R OGRAPHY Besides, in difference to two or multistage columns used in gas chromatographs, as in case of the analysis of natural gas under flow, it becomes possible to resolve analytically complex problems on one single column by on each component bar - focusing. Altogether this is not the only advantage of CHROMA BARO GRAPHY. On the contrary new possibilities of its modifications are opened with the aspects of synergism in the field of combined application of the moving gradients of pressure and temperature (CHROMA BAROTHERMO GRAPHY) or moving the pressure – gradient along the column simultaneously with temperature programming affected equally on all the separation column (CHROMABAROGRAPH with temperature programming ). In addition to the other advantaged of scientific value, the possibility of bar – focussing on each component may be considered to solve complex analytical problems on a singular gas chromatographic column, in difference to two or multistage columns.

Chromabarography - a new technology in Chromatography. The newest technology Chromatography - Chromabarography, that protects its flight, at the beginning of XXI century, and retardation at the beginning is baneful not only in sport, but in science and economics as well. I am sure the new technology of Chromatography - Chromabarography - will be useful not only as a high - efficiency method / Hayrapetyan's Effect / of analysis, but will also enrich it as a scientific discipline. Proposing the modern technology by "switching on" the electronic market Internet, I am ready to discuss any question in the frame of the information postulated on the server http://chromatography.free.fr

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By ratna dewi on Tuesday, June 1, 2004 - 10:13 pm:

I'd like to analyze the water content in my sample using gas chromatography (TCD Detector). The sample (liquid) content water, acetic acid,
1-butanol, and butyl acetate. Would you please suggest me what type of column to apply? And also, please give me information the operation condition for this analysis. Thank you

Best wishes,
dewi

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By Lars on Saturday, July 24, 2004 - 05:17 pm:

Dear Anonymous on Tuesday, June 1, 2004

The Shimadzu GC's have had Constant Linear Velocity control for years. GC-17A and GC-2010 models.

That was before the XXI century

Look it up