Non-Colorimetric EDTA Quantitation

[Nalizer]

I need to quantitate EDTA in my drug product. Google shows bunch of calorimetric approached with Cu, Fe, etc and a few references with IP. Can anybody provide with the idea how to do this by reverse phase or ion-exchange HPLC

Thank you very much

N.

[Consumer Products Guy]

We assay for EDTA using RP-8 column and UV detector after complexing the EDTA with Cu, and it works quite well. Unfortunately, the procedure is proprietary, so I can't share any more details, but it was developed using information from an EDTA supplier, so check with those.

[Noser222]

We do a method where we complex the EDTA with Iron and then use ion-pair reverse phase. The mobile phase is 20 mM Acetic Acid/Sodium Acetate, pH 3.6, with 1 mM Tetrabutylammonium Bromide, and 5% Methanol. Detection is at 254 nm

Here is a reference that is similar:

Loyaux-Lawniczak, S., Douch, J., Behra, P. Fresenius J Anal Chem 364, 727-731 (1999)

[rhaefe]

Cu-EDTA or Fe-EDTA complexes can also be seperated on an anion exchange column. Application notes here:

http://www.hamiltoncomp.com/cgi-shl/pro ... pplist2184


Robert Haefele
Hamilton Company
rhaefele@hamiltoncompany.com

[Nalizer]

Thank you everybody.

I was looking for a reverse phase methods without Ion Pairing Reagent, as I have bunch of compounds in my sample.

Robert,

what is the capacity for Hamilton methods you are using very low concentration of EDTA and sulfuric acid. What will happen if concentration of EDTA is high?

Regards,

N

[lfeeley]

Has anyone given you the answer you are looking for?
I have tried about 8 different methods to determine EDTA in polymer.
I have 5 columns with greater the 4k backpressure now.
I would LOVE the answer to this. I believe that the EDTA is bonding to the metal in the column. My next attempt will be pH gradient. I am at a loss for why such a simple thing is not working.

[Noser222]

lfeeley,
What kind of polymer are you analyzing? We analyze for EDTA in a polymer, but fortunately we can digest the polymer with an enzyme. I think your backpressure is caused by polymer getting stuck in the column...not the EDTA.

[Mark Tracy]

While working on analysis of a different chelator by ion chromatography, I found that adding calcium carbonate to the mobile phase and the sample greatly improved peak shape and retention time stability. That way random trace metal contaminants in the system were masked by a controlled amount of the calcium. Zinc probably would work also.

[lfeeley]

Your suggestions were great. I apreciate it.
FYI in the end, I modified a hamilton method using PRP X-100. First step is to dissolve my samples in base pH10.8 to open the EDTA. Next, filter them using YM3 cutoff filters to separate the EDTA from the polymer. Next I take the filtrate and treat it with Iron Chloride. I tried Nickle, Iron and Copper and Iron gave me the strongest response weight to wieght even if only slightly.
That is it for sample prep. The mobile phase is 3mM Sulfuric Acid.
I can detect to 30 ppm in a sample.

[Einar Ponten]

It is very simple to retain EDTA on a ZIC®-HILIC column using standard conditions. For concentrations commonly used in formulations a UV detector may be sensitive enough, but otherwise HILIC is perfectly well suited for LC-MS ESI.

[dpr]

We have an EDTA (total as edta) method on a Dionex IC.

An AS10 column.

There is also a voltametric method that would allow total and free edta to be determined (Metrohm application notes)

[jdlh199]

We have a method for the determination of EDTA in water/biological samples. We use a C18 column, 10cmx3mm and a 20ml/L TBAH buffer adjusted to pH3.5 with formic acid. Flow is 0.8ml/min with backpressure of about 1000psi with a clean column.

We prep samples by derivitisation with an iron solution and inject 30ul. UV is set at 256nm, EDTA peak is ~2.75 mins and we get an LOD of about 5ppm.

We also have an LC-ICPMS method that is essentially the same method but replaces iron with a rare earth element, with ICPMS detection. LOD is 50ppb.

[Bryan Evans]

We have an EDTA method using our Unison UK Phenyl column:

http://www.imtakt.com/TecInfo/TI261E.pdf