Firstly the definition of measurement should be clearly defined prior to the analysis, e.g. is the analysis for total phosphorus (this includes enzymatically released phosphorus from sources other than phytic acid), or phytic acid? 

The Phytic Acid (Total Phosphorus) Assay Kit  measures the total phosphorus released by phytase and alkaline phosphatase. The measurement is given as grams of phosphorus/100 g original material. When measuring for phytic acid the assumption is that all of the phosphorus that was measured is released from phytic acid (IP6) and therefore the amount of phosphorus released is then converted to an amount of phytic acid where phosphorus comprises 28.2% of phytic acid.

Product Page (K-PHYT)