So I was doing some redox titrations for a school assignment to find iron concentration levels in various supplements, for some reason unknown to my teacher as well as me, the endpoint could not be found. I was using potassium permanganate, the pink colour would come, but disappear 20-30seconds afterward. I took the reading and did the calculations neccesary to find we had surpassed the theoretical value by over 600%.
I was wondering is their a better method for determining Iron concentration?