An aliquot of 0.4 ml of sample, standard (phytic acid solution in 0.2 M HCl) or blank (0.2 M HCl) were added to 0.8 ml of ferric solution (0.05 g of FeCl3 in 500 ml of 0.2 M HCl) in an airtight stoppered vial and was heated for 1 h in a glycerol
bath at 80 C with agitation at 10g.