I would like to determine agmatine (C5H14N4 CAS 306-60-5) with LCMSMS. The samples are sport supplements. The processing should be just dilute and shoot . I have not yet succeeded in achieving a chromatographic separation. An eluent with formic acid and methanol or acetonitrile as well as pH 10.1 on a C18 column did not work either. I have also tested an amino column and a HILIC. Unfortunately all without success. Has anyone of you already solved the separation problem - without a derivatization step. The targetconcentration shoud reach down to 1ng/kg. (1g Supplemetpowder dilute in 10ml MeOH/H2O 1:1, 5 min ultrasonicbath, 100µl of clear extract mixed with 900µl Water, vortex -> direct LCMSMS 5µL InjVol)
Thank you for your tips, in advance!
Dirk
Hi Dirk Siekmeier ,
you might find the following articles interesting:
Development and validation of an LC–MS/MS method
for the determination of biogenic amines in wines and beers
Katarzyna Nalazek-Rudnicka, Andrzej Wasik
DOI 10.1007/s00706-017-1992-y
And two Application Notes showing the use of cation exchange chromatography, which can be combined with MS (not shown in the report) after the application of continuous desalting (aka suppression of the high eluent conductivity) as well.
While the first publication relies on the derivatization with tosyl chloride to enhance chromatographic retention, the following two documents benefit from using ion-exchange interactions. In case interested, please let me know, and we could discuss some weird thoughts of mine offline.
I hope there is something in this for you.
Good luck with your research
Detlef.
Thermo Scientific™ Acclaim™ Mixed Mode WCX-1 HPLC Columns with HILIC or ion exchange gradient would be proper. You may also look to Sielc Primiseps for the same interaction.
However, I am not sure 1ng/kg is possible to detect by applying dilute and shoot. What is your instrument and presenting sensitivity? I suggest to prefer enrichment or derivatization instead of dilute and shoot and HILIC chromatography if you don't have to. If you have to use dilute and shoot, post-column derivatization may be an option if your configuration is allowing to perform after HILIC separation.
Do not forget to look at the application and methods based on the analysis of arginine and guanidine since they have similar structures. here is one of the example of mix-mode application to monitor the guanidine;
https://www.sielc.com/Application-HPLC-Application-For-Retention-of-Guanidine-By-Mixed-Mode-Chromatography.html
Since Agmatine is (4-aminobutyl)guanidine, I would try to detect and quantitate the guanidine moiety and it's side groups.
Thank you, dear colleagues for your tips. Please excuse me, I was wrong about the concentration, 1 mg / kg is the value that should be achieved. I calculated in the wrong direction. Thanks to İsmail Emir Akyildiz and Noel W Davies for pointing this out and also to the others who must have recognized the problem. Nonetheless, I think ion exchange chromatiography will be the best way to separate it from agmatine. Unfortunately I have no experience with it and no matching column in the laboratory. I won't be able to report on a solution that quickly. Thanks again and best regards - Dirk
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