Dear all,

I want to prepare a 0.05 M, pH 7 phosphate buffer solution that contain 1% w/v casein and 0.006 M EDTA for proteolytic activity determination. As I know, EDTA and casein only dissolve in a basic solution. My idea is to dissolve EDTA and casein in dibasic first, and then only put the monobasic solution. Is it correct? Can anyone suggest the correct, detail steps to prepare and maintain the concentration?

The statement of my reference is (I want to prepare it without cysteine): The extract (1.0 ml) was mixed with 1.0 ml of a reaction cocktail (contained 1% (w/v) of casein, 0.03 M cysteine, 0.006 M EDTA in 0.05 M phosphate, and a buffer pH 7.0).

Ketnawa, S., Chaiwut, P., & Rawdkuen, S. (2012). Pineapple wastes: A potential source for bromelain extraction. Food and Bioproducts Processing, 90(3), 385–391. https://doi.org/10.1016/j.fbp.2011.12.006

Your help is greatly appreciated and I thank you in advance.