The released
inorganic phosphate was measured by adding with
750 Al of colour reagent prepared daily by mixing four
volumes of 1.5% (w/v) ammonium molybdate
(Sigma, A7302) in a 5.5% (v/v) sulphuric acid solution
(Carlo Erba Reagenti, 410301) and one volume
of a 2.7% (w/v) ferrous sulphate (Sigma, F-7002)
solution.