After
that, an aliquot (30 ll) of the reaction mixture was dissolved in a
3:1 (v/v) H2O–MeOH solution (2.91 ml), and a 10% aqueous
solution of NH4SCN (30 ll) and 20 mM FeCl2 in 3.5% HCl (30 ll)
were added; after 3 min of incubation at rt, the absorbance was
measured at 546 nm against the corresponding blank.