Because it seems like it depends on the laboratory, but i really like to know if buffers (Tris, Phosphate, Krebs or McEwen) are not specific to a type of organ
If yes, what is this specificity characterise with
Definitely it's not related to the organ. It depends first of all on the pH you want to maintain - because the effective buffering ranges of, say, citrate buffer, phosphate buffer, glycine-NaOH buffer are very different. Phosphate is great if you want to buffer at pH 7 but not much good if you want pH 8.5. The pH you choose depends on what you want to measure e.g. if it is an enzyme activity you want to know the optimum pH and perhaps also the stability of the enzyme in that buffer. It is important to bear in mind that enzymes don't always enjoy the same buffers. Thus at pH 7.5 both Tris and phosphate are good buffers but some enzymes are quite unhappy in Tris (i.e. they inactivate) and others just love Tris and are not so happy in phosphate. So try buffers out and see what work best for you. Also make sure you take into account that other things you add to your mixture should be pH-adjusted if they are at high concentration - an acidic substrate could overwhelm the buffering capacity of your chosen neutral pH buffer for example.
oh thank you very much for explanations Paul. I was really completely lost !!
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