Difference Btw Ultrasphere Octyldecyl Silane & XTerra®C18

[Organic_chemist]

I want to know the difference between Beckman C18 RP Ultrasphere Octyldecyl Silane & XTerra®C18 HPLC column

I am analyzing a sample using XTerra®C18 HPLC column( due to availability in my Lab), but I am not getting any peak. The sample is basically metal ion complex having positive charge. May be the sample is stuck inside the column ( my observation maybe wrong)

The actual protocol (reference paper) is using Beckman C18RP Ultrasphere Octyldecyl Silane column.

So, I want to ask that is there any difference between these two column.
Between I am not expert of HPLC columns.
Thanks in advance.

[tkubowicz]

Hello

In general (I repeat "in general" just in case if someone will write that I'm wrong) there is no difference in terms of stationary phase type (they will have different parameters like: carbon load/porosity/bonding rtc but it is completly different story) so you should see peaks coming out from column sooner or later (if they are properly detected of course)

If someone was using your Xterra column with Ion Pair reagents (sulphonates, ammonium salts) it is possible that stationary phase is "loaded" and you have "ionic" stationary phase - ion pair compounds are difficult to remove from colummn.

So I'd recommend to run this method with new column.

Regards

Tomasz Kubowicz

[Organic_chemist]

Hello, tkubowicz

I am using the same protocol of mobile phase ion pairing buffer as mentioned in the reference paper ( 0.05M Triethylammonium phosphate buffer pH 2.5 & Methanol with gradient elution) but with different stationary phase ( with different column).

I have confirmed the synthesis of metal ion complex using TLC but while doing HPLC I am failing to get required peaks. I have repeated the results using different XTerra analytical column column but in-vein.

So, what i concluded that mine XTerra Column ( which we always used for the separation of organic compound from mxiture in my Lab) for this kind of metal ion complex is not suitable.
I have tried different mobile phase system but not even single mobile phase is working.

[tkubowicz]

Hello

Give us more information:
1.Method parameters (gradient, temperature, detector )
2.Compound type (structure)
3.Sample prep (solvents)
4.Paste chromatograms

Regards

Tomasz Kubowicz

[tom jupille]

Those two columns are not even close.

If you use the column selectivity database on hplccolumns.org (http://hplccolumns.org/database/compare.php) -- this is the same database as the "PQRI" database on the USP web site (http://apps.usp.org/app/USPNF/columns.html), you will find that they have a similarity index ("Fs value") of 40. To put this in perspective, Fs values < 5 are considered "plug and play" replacements; Fs values between 5 and 10 are considered "similar".

This really isn't surprising. Even though the bonded phase on both columns is octadecyl, the underlying support material is quite different. The Ultrasphere column is based on silica gel while the Xterra column is a hybrid "BEH" silica which incorporates ethyl linkages in the backbone.

[Organic_chemist]

Hello, Tom Jupille

What I understand that these two column are totally different.
I found lots of reference paper using Ultrasphere Octyldecyl Silane column for this application( that I am using)

It mean the column I am using is not suitable for this application because XTerra supporting material is composed of Inorganic (silica) and organic (organosiloxane) component ( hybrid particle Technology) where as in Ultrasphere column the supporting material is only Silica gel.

[Organic_chemist]

1. The HPLC gradient was made up of an isocratic elution (100% A) for the first 0 ~ 5 min; a linear gradient of 100% A/0% B to 75% A/25% B for 5 ~ 8 min; a linear gradient of 75%A/25% B to 66% A/34% B for 8 ~ 11 min; a linear gradient 66% A/34% B of to 0% A/100% B for 11~22 min; and an isocratic elution (100% B) for 22~25 min.

2. Detector UV & radiodetector.
3. structure of compound ( complex) Tc(CO)3(H2O)3
4. sample pre. solvent Phosphate buffer


Regard

[Gerhard Kratz]

I agree with Tom.
C18 is never the same. Please check the hydrophobicity table.
With ion pair reagent in the mobile phase a XTerra C18 will get modified on the surface like all other silica based C18 phases.
About 500 parameters are important for the silica and the silane on the surface.
If the Ultrasphere C18 is recommended, us it. There are no bad columns on the market. They are all good for certain application. Good luck.

[Organic_chemist]

I check the column database and compared two column but still I can't able to figured out the difference between two column. I am not expert of HPLC column so kindly share your experience and expertise.


http://tinypic.com/m/jpfqea/3

[tom jupille]

I don't want to sound condescending, but if you are brand new to HPLC, you are unlikely to understand the explanation. Suffice to say that those two columns are quite different; a method developed using one is unlikely to work on the other.

If you want to pursue it, the explanation of the "PQRI" parameters is here:
http://www.usp.org/pqri-approach-column-equiv-tool

For a grounding in the basics of column chemistry, check out the "Fundamentals of HPLC" course (registration is free):
https://www.analyticaltrainingsolutions ... ls-of-HPLC

[lmh]

This is still worrying me. My (admittedly very limited) experience of C18 columns is that, at least with gradient methods, even if the peaks shift around a lot, an analyte that elutes from one C18 column will always elute somewhere from another. The method may fail through loss of resolution, horrible coelutions and possibly bad peak-shapes, but it won't generally fail through complete loss of the peak(*). This is a metal ion complex - has it fallen apart during analysis? Has the choice of solvent messed up its detection somehow? What is the detector, anyway? Puzzled...

(* although in an isocratic method, complete loss isn't too hard to achieve)

[mattmullaney]

Hi Imh,

You'd be shocked at what can happen with C18 phases...I've seen too many troubles that when I hear "Oh, all C18 columns are just the same..." I scoff. You're correct about isocratic methods...you have to be careful to ensure that everything (as much as can be derived) elutes off of the column. Makes some good sense to develop methods with broad gradients ending in high %Organic composition to me...or to do the "old-school" isocratic development by starting at 10:90 water-to-organic and stepping backwards in %Organic by 10% or so. When I did extractables work at Gore, hardest thing was to ensure that all of the substances in the mix I put on the column actually came out...and sometimes I used C5 or C3 phases. Some stuff, they're just really hydrophobic.

[mattmullaney]

Hi Organic_chemist,

To clear things up to me, was the Waters XTerra an RP phase (so-called polar-embedded phase, carbamate functionality) or an XTerra MS phase (C18 without a polar-embedded group)?

Tom is absolutely correct, though. I'd not use either in place of the Ultrasphere...base material is very different, XTerra is made up of a hybrid organic-silica backbone while Ultrasphere is silica only (type B). If you would like I could send links to Synder's work describing all of those parameters at hplccolumns.org...suffice it to say I've used this site a ton and you can rely on the predictions made.

As to the XTerra RP vs. the XTerra MS, I had to learn this difference the "hard way" trying to separate monodechlorovancomycin from vancomycin B. Won't make that mistake again anytime soon!

[Organic_chemist]

Hi, Imh & Matt

Now I start getting peak but peak is very broad and shape is not good after trying different solvent system and buffer with different gradient elution.


My column is XTerra RP phase, supporting material is composed of Inorganic (silica) and organic (organosiloxane) component ( hybrid particle Technology)

I know xTerra MS RP where supporting material is silica type B. Some paper also used this column for the analysis of metal ion complex. But most of the paper utilized Ultrasphere Octyldecyl silane column. So, what I think that the column i am using is not suitable for particular application.

Regards,

[mattmullaney]

Hi Organic_chemist,

Hard for me to say. What I know is that the XTerra RP phase has a carbamate group embedded between the base hybrid organo-silica material and the C18 ligand. Perhaps it could cause a "drag" on the complex. When I did some work with metal-EDTA chelates, and with the PET agent 68-Ga Edotreotide (another fancier sort of EDTA chelate), the columns employed have silica-only based stationary phase w/C18 ligand. I think you may be on to something, but maybe because of the polar-embedded group as opposed to the hybrid organo-silica.

Just a guess. Ultrasphere is silica-only, and not polar groups embedded within.