I need help understanding isoelectric point determination for my research.
Background: Im preparing a plant protein to create a coagulant and I need to determine its isoelectric point to identify the range where its surface charge is positive.
I read online that the isoelectric point can be determined by measuring the zeta potential at different pH values then plotting a graph of zeta potential vs pH and finding the intercept. What I've seen online is that adsorbents are dissolved in DI water then mixed with salt solutions at different pH values but my challenge is that my proteins are being extraction from the plants and are in solution.
What's a viable way to determine how much protein solution I should dilute with salt solution since I cant measure out how much protein I need on a mass basis? I've seen some references say that they diluted the protein solution to 1% protein and 99% salt solution, is that reasonable? Maybe I could precipitate the proteins out of solution and dissolve that in my salt solutions.