protein in phosphate buffer precipitate out after added Acetonitrile

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mofeifei
mofeifei's picture
protein in phosphate buffer precipitate out after added Acetonitrile

I want to analyze BSA by using RP-HPLC. Usually my BSA protein will just be in water solution. After adding acetonitile before HPLC, there is no precipitation. But recently, my protein need to be in phosphate buffer pH 6.8. So when I mix it with Acetonitrile, it precipitate out. What should I do?

Also, I have heard that protein will precipitate out with acetonitrile. Then why most of the analytic method are using acetonitrile?

Waiting for the answers..............Thanks a lot.

Neznika
Neznika's picture
you don't need to add

you don't need to add acetonitrile to a sample before HPLC. How much acetonitrile did you add to protein solution?

mofeifei
mofeifei's picture
Without acetonitrile in my

Without acetonitrile in my sample, the peak will split into three. But with acetonitrile (50%) mixed with my sample, I got a pretty good looking peak.