I've been researching this for weeks now but I still can't find the answer.
I'm going to do an experiment where I calculate the content of calcium in different samples of tofu. The tofu has been squeezed to its bare nutrients already, and while I want to do a simple titration with EDTA and the tofu solution, (EBT as the indicator), so I can easily calculate the calcium content based on the amount of EDTA used.
However, my teacher is telling me a more accurate way is to do a back-titration using MgCl. Does anybody know how this would work? Would I drown the tofu solution with MgCl, and then do the titration with EDTA? But then how would I calculate the calcium content?