Transfer a sample solution containing no more
than 500 mg Zn(II) to a 25 ml volumetric flask,
add 2 ml of 1104 mol l1 XO and 1 ml of
1103 mol l1 CPC, adjust the pH of the
solution to 5.5, dilute to the mark with distilled
water, mix well and allow to stand for about 30
min.