[chisti_2k]

How can I determine a given sample of STPP (Sodium Tripolyphosphate/ Na5P3O10) is Food Grade or Technical Grade ?

[STPP Expert]

Hi that is easy .
U need determinated As(arsenicum)  content in the sample.
technical grade content is up to 10-20 ppm, Food grade is about 1 ppm.
That is main diferens ,if STPP is made from termical PA.
If it's made from L/L PPA you can check also Fe content if that is easy for you .TG STPP content 50-80 ppm Iron afront of 5-10 ppm for FG.