Chromatography Forum

Hi everyone,
I want to know what is the significance of 1-Hydroxy1-cyclohexene peak in a urine sample.I have extracted the patient urine sample and after derivetizing with BSTFA+TMCS injected it into the GCMS. The chromatogram of the patient shows a peak at Rt 8.9 min that shows 99% match with the above compound and its peak height and abundance is also markedly increased.I have never come across this peak in such higher abundance.I had tried to search about this compound on internet but i didn't got the details.So please somebody help.

Thanks
Chandra

If you found this compund, it would be from enolization of cyclohexanone in the derivitization process. You can take a bit of cyclohexanone, derivatize it and see if you get a corresponding peak. You should see far more cyclohexanone in the mix, however. And, if you have the compund you think, you should see cyclohexanone in the urine sample as well.

I will note that the retention time alone does not tell us much -- the retention time is dependant not only on the compund but also on the column stationary phase, dolumn dimensions, gas flow, and temperture program. A 99% match is a good start - but it is a suggestion. You may have a second or third possibility listed. Be sure all strong ions present in the library spectrum are present in the unknown. And, strong ions preent in the spectrum, not present in the library spectrum are a warning that you have confounding information or a different compund present. And, with urine - I have noticed that there are many compunds in urine that do not show up in spectral libraries - but you will get a "best match" anyhow.

The patient here, is suffering form urea cycle defect, is it possible this compound will excrete in urine of this patient. What is the significance of this compound in urine.

Chandra

You may have identified a chroamatographic peak associated with urea cycle defect, but I would go back and check the identification of the peak. Discussions of cyclohexanone in urien appear to relate to exposure - and the compond is metabolized in the body, so you should see the related metabolites. If you can confirm that the chromatographic peak you are looking at is from cyclohexanol, I would look for sources of possible contamination of the sample - perhaps from plastics being used in sample collection of handling - or recient exposure of the patient to cyclohexanone.

And, you may have identified a chromatographic peak associated with what the patient had for lunch. Be sure that you find this peak in more than one sample and look for time related trends. A compound that shows up once, reaches a maximum and decreases over several hours may be exposure related. A compound that shows up in one urine collection but not in the void prior to that collection or subsequent to that collection may just be a contaminant in that collection. There is a paper that comes to mind that shows the excretion profile of metabolized PAHs with the metabolites bein excreted over a number of urien voids. (Authors in include Li Romanoff and Sjodin - I don't have a copy with me at home.)

I would expect that the product from an ongoing metabolic issue would be found over several days. Again, looking at the time profile within a day may help.