Gentamicin Analysis HPLC - UV

[Fábio]

Dear
In google "Determination of Gentamicin Released From Orthopedic Carrier System by a Novel HPLC Method"
I used the same condition that method, but it no worked.
Have you ever seen this method and could help me?

Thank you very much

Best regards

Fábio

[Vlad Orlovsky]

gentamacin has no UV activity, any impurity in gentamicin will mislead you. You need to use ELSD, LC/MS or derivatization to make it UV active

Something like this:

http://www.sielc.com/Compound-Amikacin.html

I look at the article and they measure UV at 280 nm! How this even possible to monitor amino sugar at 280 nm, unless they are doing indirect detectiion

[gapeev]

That's absolutely correct, gentamicin has very low absorbance rendering HPLC-UV useless for all practical purposes.

Some time back I was asked to help choose a gentamicin supplier. Gentamicin was to be a component of some novel drug formulation.

It turned out that as of ~2010 there were only four manufactures, so I was told, three of them were from China. I set up a generic LC-MS run and turned out that all four samples were not pure, softly speaking. The expected gentamicins (I used plural as there are several formed during fermentation) yielded abundance of ions and flat UV. There were other compounds with substantial UV signal and that what what the paper authors were apparently looking at. Let's call it compound X.

In the paper they claim LOD to be ~1ppm. That's strange, if this impurity content is about 5%, then LOD for compound X becomes ~50 ppb. Is it reasonable even for strong UV absorber?

That's unfortunate such a paper got published.

[Fábio]

Dear friends
I am very grateful to you who helped me with their answers.
Thank you very much.
Still on the subject gentamicin, ...
Do you know some method gentamicin content (HPLC - UV) by derivatization with 1-fluoro-2,4-dinitrobenzene?
Could you provide me ?
Thank you very much.
Best Regards.
Have a good week.
Fábio

[oscarBAL]

Hi Fabio; what is the level that you need to quantitate? If UV is your lonley option... then I would prefer to do Indirect UV than Derivatization as Vlad mentioned; reason is simplicity and espicificity.

sorry for my spelling

[JMB]

See below (available on-line, free) for exptl. details of derivatization with 2,4-DNFB of an amino-bisphosphonate (alendronate)
N.B. this is not an HPLC method !!


Chemistry Central Journal
April 2012, 6:25,
Open Access

Validated spectrophotometric methods for determination of Alendronate sodium in tablets through nucleophilic aromatic substitution reactions

Mohamed I Walash,
Mohamed E-S Metwally,
Manal Eid,
Rania N El-Shaheny

» Download PDF (306 KB) » View Article

As already stated, your gentamicin is very likely to be a mixture and you will need to resolve the components by HPLC. Doing a lit. search for indirect UV-detection ion chromatographic method for alendronate (without derivn.) reveals several procedures. However, ion-chromatography may not resolve the isomers adequately.

Depending on time/cost constraints, you may want to pursue the derivatization procedure initially to assess the chromatographic complexity of your analyte. If your analyte is "clean", then an indirect-UV IC method may be acceptable.

Please let us know what does/does not work.