Solution C (hydrogen peroxide, 8.8 mol l
ÿ1): hydrogen
peroxide was used as supplied by the manufacturer
i.e. acid-stabilised to pH 2.0±3.0.
Solution D (ammonium acetate 1.0 mol l
ÿ1): 77.08 g
of ammonium acetate was dissolved in 900 ml of
water. The solution was acidified to pH 2.0 with
concentrated nitric acid and made up to 1 l