Orthophosphate, phytate, and total phosphorus determination in cereals by flow injection analysis.

VIEIRA, E. C.; NOGUEIRA, A. R. de A.

Orthophosphate, phytate, and total phosphorus determination in cereals by flow injection analysis.

Autores

Descripción

A flow injection spectrophotometric procedure with enzymatic hydrolysis was developed for determination of orthophosphate, phytate and total phosphorus in cereal samples. Phosphorus species were extracted from cereals with 0.05 mol L-1 potassium hydrogen phthalate buffer solution at pH 5.7. Orthophosphate was directly determined in the extracts by molybdenum blue spectrophotometric method. The phytate was hydrolyzed by the enzyme phytase coupled to a solid phase packed into an enzymatic reactor, and the resulting hydrolyzed orthophosphate was also determined by spectrophotometry at 650 nm. After optimization for phosphorus species extraction and enzymatic hydrolysis, a linear calibration graph was obtained up to 196 × 10-6 mol L-1 orthophosphate (P conc) -2.67 + 0.52x, r ) 0.9998). Measurements are characterized by relative standard deviation of 1.6% for a standard of 72 × 10-6 mol L-1 orthophosphate and no baseline drift was observed during 4 h operation periods. It provides 72 measurements per hour, with 2.4 × 10-6 mol L-1 and 7.9 × 10-6 mol L-1 as detection and quantification limits, respectively.