(a)Pipet 5mLof the clear
Assay preparationinto a flask,add 25.0mLof isopropyl alcohol,and mix.Pipet 5mLof the isopropyl alcohol dilution into a glass-stoppered,25-mLgraduated cylinder or test tube,and add in succession,mixing after each addition,1.0mLof
Ammonium chlorideammonium hydroxide buffer,1.0mLof sodium acetate solution (1in 5),and 1.0mLof water.Cool to about 25

,then add 1.0mLof
Chlorimide solution,shake vigorously for 10seconds,accurately timed.Sixty seconds,accurately timed,after the addition of the
Chlorimide solution,determine the absorbance at the wavelength of maximum absorbance at about 650nm,with a suitable spectrophotometer,using water as the blank.
[NOTEMake the reading promptly to avoid errors due to fading of the color.
]Designate the absorbance as
AU.