Flushing Cu mobile phase

[mark.owens]

Dear users,
I have a method using copper in the mobile phase and was looking for guidance on flushing the system to make sure all of the copper has been removed from the system. Could I please get input on the best method/mobile phase to flush the system with?
Regards,
Mark

[DR]

I'd be inclined to pull the column and flush w/ some 2-3N HNO3, followed by lots of water.

[Karen01]

I assume you are using a chiral column... and I'm probably running a similar one...

What we do is take the column off, flush the system well with water and then with organic in preparation for a different column/mobile phase...

We don't see an issue... What is the problem you see?

- Karen

[mark.owens]

I assume you are using a chiral column... and I'm probably running a similar one...

What we do is take the column off, flush the system well with water and then with organic in preparation for a different column/mobile phase...

We don't see an issue... What is the problem you see?

- Karen

Karen,
I haven't seen an issue yet. Last time I tried the nitric acid flush suggested by another reader here, but it took several hours to flush all of the nitric from the system so I was looking for an alternate flush procedure to make sure the copper was gone. I am actually determineing EDTA and DTPA on a RP column and have nightmares about the copper carrying over into another column and analysis.
Thanks for your reply,
Regards,
Mark

[prepcolumn]

For EDTA: try HAMILTON PRP-X100, 4.1 x 150mm 10μm, 250 nm, pH:3.5 buffer:acetonitrile (75 : 25) after complexation of EDTA with ferric chloride..

Good luck

[Consumer Products Guy]

I am actually determineing EDTA and DTPA on a RP column and have nightmares about the copper carrying over into another column and analysis.

Mark, we do EDTA and DTPA on a C8 column using copper in the mobile phase, and don't see any real issues. I feel for this that it's best to dedicate a column for this assay, but that may be more because the mobile phase we use is aqueous.

We flush the system and column with HPLC H2O for 15 minutes at 2 ml/min., then pump through with about 20% HPLC methanol or 20% acetonitrile.

[mark.owens]

I am actually determineing EDTA and DTPA on a RP column and have nightmares about the copper carrying over into another column and analysis.

Mark, we do EDTA and DTPA on a C8 column using copper in the mobile phase, and don't see any real issues. I feel for this that it's best to dedicate a column for this assay, but that may be more because the mobile phase we use is aqueous.

We flush the system and column with HPLC H2O for 15 minutes at 2 ml/min., then pump through with about 20% HPLC methanol or 20% acetonitrile.

Would it be possible for you to share your method for the EDTA/DTPA? Will send you my e-mail address if it is OK for you to share.

[Consumer Products Guy]

Would it be possible for you to share your method for the EDTA/DTPA?

Unfortunately, that is considered proprietary, from a supplier of chelating chemicals. All I can share is that the mobile phase is a mixture of quaternary ammonium surfactant and copper sulfate at pH 4.2 with acetic acid/NaOH (no organic solvent) and samples are made up in dilute copper sulfate. RP-8 and UV detection is used.