Hydrocodone [July 4, 2004]

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

3 posts Page 1 of 1
By Anonymous on Sunday, July 4, 2004 - 06:04 pm:

Hi
I am testing the assay for Hydrocodone.
The problem I am having is the tailing is above 1.00, which is requried. The mobile phase is Phosphate ammonium monobasic and water and MeOH and water. Any suggestion will be helpful.

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By Anonymous on Tuesday, July 6, 2004 - 09:44 am:

1.00 seems like an overly strict requirement since it implies that the peak is perfectly symmetrical or fronting. What is your tailing actually running?

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By DR on Wednesday, July 7, 2004 - 08:48 am:

Hydrocodone - tails at least a little in every method I've seen for it. Maybe in plasma samples (very low conc.) it would be okay, but for any pharma run, expect some tailing.

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By al on Wednesday, July 7, 2004 - 01:37 pm:

try a couple of things (I am assuming this is a USP method):

with a C8 column (which is what I assume you are using) the maximum operating temperature is 60ºC. First, check the temperature of your heater to make sure that it is what the equipment says it is. Try dropping the temperature to 54ºC (within the 10% USP allows). This will prevent the column from losing its endcapping.

increase the flow rate

increase the sampling rate

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By Zelechonok on Wednesday, July 7, 2004 - 02:50 pm:

If you want completely eliminate tailing of compounds like Hydrocodone you may consider to use column technology that was specifically developed for retention of very basic compounds. The idea is to use RP column with embedded positive surface charge rather than negative which is typical for most silica based columns even end-capped. This positive charge eliminates completely any ion-exchange interaction of the basic analytes with acidic silanol residues. Some examples are:

http://allsep.com/makeChr.php?chr=Chr_065

http://allsep.com/makeCmp.php?cmp=Cmp_110

http://allsep.com/makeChr.php?chr=Chr_047

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By HW Mueller on Wednesday, July 7, 2004 - 11:41 pm:

Completely?

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By allen on Thursday, July 8, 2004 - 02:38 pm:

USP has postponed the April 1, 2004 revision to Hydrocodone Bitartrate. You can go back to the original method in 27. If you need documentation, go to USP.org, and look at the right of the page for postponed documents
HILIC
Chromatography Forum: LC Message Board: HILIC
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By Tristan on Sunday, July 4, 2004 - 08:46 am:

G'day all,
I am relatively new to liquid chromatography and only have experience with RP-HPLC. I have noticed in a few conversations that HILIC is mentioned/recommended. In what situations is HILIC best? Can someone please suggest some references or reading material on this subject?

Thanks all!!

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By Chris Pohl on Saturday, July 10, 2004 - 02:33 pm:

HILIC is just another name for normal phase chromatography (it's supposed to stand for: Hydrophilic Interaction Chromatography). The acronym for this should have been HIC but this acronym was already taken for another technique: Hydrophobic Interaction Chromatography (previously known as Salting Out Chromatography). There are quite a number of references on normal phase chromatography but I would recommend you start with Snyder and Kirkland's book on HPLC.

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By Einar Pontén - SeQuant AB on Sunday, July 11, 2004 - 02:12 am:

I don't agree! HILIC does mean something else than "normal phase".

In HILIC you use a hydrophilic stationary phase (as in normal phase) and a water soluble mobile phase (as in reversed phase). That offers you a tool to retain very hydrophilic and water soluble compounds, like carbohydrates, amines, alcohols, acids.

A recent paper is:
"Determination of neomycin by LC-tandem mass spectrometry using hydrophilic interaction chromatography"
Oertel, R., Renner, U., Kirch, W.,
J Pharm Biomed Anal 35(3) 633-8, 2004

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By tom jupille on Monday, July 12, 2004 - 09:55 am:

But the fact is that the term "normal phase chromatography" has been applied to the type of system you describe for *at least* the past 20 years (carbohydrates using amino bonded-phase columns with water/acetonitrile mobile phase). If tagging a useful technique with a new name helps to popularize it, fine, but we should at least recognize the relationship (IMHO).

How about just recognizing HILIC as a subset or special case of normal phase?

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By Einar Pontén - SeQuant AB on Monday, July 12, 2004 - 03:20 pm:

OK, you are correct there are not that sharp borders between techniques. However, for a lot of chemists and a long time "normal phase" has been identified as a technique where solvents immicible with water are most common. HILIC is based on the use of solvents commonly used in reversed phase.

By they way, "HIC" mentioned above is better described as "salting out chromatography" although the new name might have popularized it...
By Zivd on Friday, July 2, 2004 - 05:47 pm:

Dear Friend!
i am working on identified the active material in root exudate that attract kind of worm, i did several tests and know i want to do one of the separation method. ( according to my tests my active material is cation charge, is adsorption to RF colona is not destroid in High Temp )
which kind of separation method i have to use?
Thank you very much for your time.
I appreciate it allot.
Ziv

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By Alexander on Wednesday, July 7, 2004 - 06:45 pm:

Ziv,

Put your mixture on a big TLC plate and run it in a polar system. Dry it down at room temperature not to degrade the attractant and let the worms to crawl to the plate. Carefully check with a pencil the area that the worms crowded, cut the band and isolate the attractant.

I do it all the time with my mosquitoes. Always works
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