I want to assay for phytic acid content in Sorghum bicolor seeds but the lab I contacted for the work says they can only assay for total phosphorous content.
The Phytic Acid-Total Phosphorus Relationship in Barley, Oats, Soybeans, and Wheat.
G. M. Lolas, N. Palamidis, and P. Markakis. Copyright 1976 by the American Association of Cereal Chemists, Inc.
The following correlation coefficients were found between phytic acid content and total P content of four seed types: 0.9612 for barley, 0.9103 for oats, 0.9852 for soybeans, and 0.9682 for wheat. This high correlation may be used for the estimation of phytic acid content through the simpler total P determination.
I believe if you took about 36 samples of various types of grain sorghum and ran determinations your relationship could be used to determine phytic acid from the Phosphorus determination which would be useful.