Best Spin Filter for Proteins / Protein Recovery

[mr2ACD]

Hello,

My lab was having a problem with our spin filter's preservatives creating a ghost peak on our HPLC. We really like them besides this. They have a dolphin tip and do not lose much protein through the filtration process.

Can anyone recommend a great spin filter that is easy to use/is great for working with proteins, specifically antibodies.

Thanks,

Matt D

[ScottHorn]

I've never had any problems with Millipore's Amicon Ultra centrifugal filters, but I'm only doing size exclusion with UV detection, so your mileage may vary. Have you tried pre-rinsing the filter by spinning some buffer through it before concentrating your actual sample? It seems like that would wash out any preservative that's present.

[mr2ACD]

I tried washing the filter out with 200ul PBS today to no avail. Still had the preservative ghost peak.

The filters I am using now are the amicon millipore 1.5ml w/ 0.5ml filter cap.

Also performing SEC and 280 UV detection.

It seems the problem is periodic with these filters. Some lots the preservatives are present and in other lots they are not.

-Matt

[ScottHorn]

Have you tried taking a filter from a lot you know to be bad, running some buffer through it, and injecting just that buffer? That would support your hypothesis that the ghost peak is coming from the filter. It would also indicate that the preservative is soluble in the buffer. If so, enough washing should get it out. Where does this preservative show up on your chromatograms? I'm guessing its a small molecule?

[mr2ACD]

This past week I tried washing with 900ul PBS prior to the injection. I haven't looked at the chromatograms yet. Iwill today.

The molecules show up 40-50 minutes after the injection. So, they show up on the following run.

Good idea to test the buffer. I will try that this week.