Hi Iman, I am not sure why you are doing vanadium analysis via HPLC.  Is your column an ion exchange column or a normal phase column?  If not, are you running an ICP on the back end of the HPLC? 

For the ghost peak problem, you can always try running an internal standard to confirm the peak is from the sample.

Dear Farrukh, Thanks for your reply.

If you look at my question, I am hoping to do speciation of vanadium V and vanadium IV within my environmental samples.

I am using a polar mobile phase (MeOH and Water) and will try ACN later therefore I am working with reversed phase column

I am planning to run AAS and ICP-MS after finding the correct conditions of concentration an pH for my standard samples.

My question was about how to avoid contamination from previous runs to quantify vanadium in the present run?

I am doing today a full washing procedure and will see how it will go?

Any input as per this regard is very appreciated.

Hi,

If you inject a succession of blanks after a sample, how does respond the unwanted peak? Does it disappear after the 1st blank?

To clean the vanadium, you can try to inject an acidified blank (with a low concentration of nitric acid, for example) between two samples. But be sure the HPLC column supports it before any injection.

Thanks Ogier,

Yes after running the blank after the first sample (Let's say vanadium standard), the vanadium peak is still there. Thus, since I am trying to undergo quantitative characterization and speciation. I am worried about contamination from previous runs. I have looked at few procedure and now:

- I wash the column with water, water:MeOH, MeOH for 20-30 minutes each at the beginning

- Run blank after running the sample.

- I have decided to run one type of sample each time (Per day)

It is time consuming, but I can see that the risk of contamination gets lower and therefore the quantitative results will be more accurate.

Are you using HPLC and vanadium in your research? If so, I will be interested in looking at your results

Thanks again

Sorry for the response delay.

Nope, I'm not currently performing HPLC and Vanadium, just trying to help. ;-)

Do you try to inject more blanks after one sample? For example: you wash the column as you described, then the sample, then a blank water, then a blank water:MeOH, then a blank MeOH.

If the vanadium peak disappear in the 2nd or 3rd blank, you'll be able to run automatically more samples a day.

Good luck in your research.

Thanks.

Effectively washing the column and running he blank few time eliminated the previously observed peak.

Hello,

About washing:

Washing with 80:20 (water:ACN) for 3 hours at 1ml/min and 80:20 for other 3 hours(ACN:water) works fine

Otherwise there are more precise procedure (source: chromacademy)

Reversed phase columns include C30, C18, C8, C4, C1, CN and phenyl stationary phases. To clean and regenerate a reversed phase column flush it with the following volumes of solvent.

20 column volumes of water/acetonitrile (95:5 v/v)

20 column volumes of acetonitrile

5 column volumes isopropanol

20 column volumes hexane

5 column volumes isopropanol

20 column volumes acetonitrile

20 column volumes of water/acetonitrile (95:5 v/v)

Re-equilibrate with the required mobile phase

Be aware that in the case you are using phosphate buffer an overnight washing of the system (removing the column) with 100%water is required. This is done in order to prevent precipitation of salts

To avoid contamination I would suggest to insert an equilibration stage between your samples. The eq. stage is for example 10 minutes in which you use the same composition as the mobile phase emplyed in your method

This stage is very useful to get rid of (any) impurity which may generate confusion during the analysis of your peaks

Regarding the blank I usually run it twice.

It may appen that the first blank is contaminated from the previous user

Kind regards