Composition of arcanite (potassium sulfate) agricultural grade. Potassium content of random drawn sample? I bought potassium sulfate from this source:
Potassium sulfate granulate
I'm using it as a potassium additive in hydroponics. The composition is listed as K2O = 50%, S = 18%. This equals about 41.5% K (50* (mass of K / mass of K2O) Calculated from mass percentages (mass of K2 / K2SO4) potassium sulfate should contain about 44.9% K and and 18% S. So based on this calculations I concluded that the potassium content is within the margin of error tolerable for fertilizer application. (About 3.4% for potassium)
However after further reading I came across an article which suggested that raw materials should be as homogeneous as possible because otherwise a sample drawn randomly could have huge variations in the content of the chemicals involved. How high could the deviation be with respect to potassium?f I think the source material is arcanite
EDIT: The security data sheet states that the purity of the granulate is guaranteed to be between 90-99%
The deviation can be in range from negligible to huge, depending on the level of nonhomogeneity and locality of the sample.
Note that routine analysis of potentially non-homogenous sources involve sophisticated sampling and sample averaging schema, so the result is representing number.