In regards to:
Does anyone have a ready reference to a titration method to determine the concentration of the peracetic solution. Post 354166
(wacko_reaco: "stability of peracetic acid", Methods Discourse) I know it is an old question, however I do not think anyone has acutally answered this effectively.
This is the method I used to use:
Materials Needed:Micropipettor/Tips
Analytical Balance
Glass Beaker 200mL
5%H
2SO
4Cracked Ice/Bath
Magnetic Stirrer/Stir Bar
Burette
Ferroin Indicator
Ceric Ammonium Sulfate (.1N)
Potassium Iodide Solution (10%)
Sodium Thiosulfate (.1N)
Startch Indicator Solution
Method:Pipette 200 µl of Peracetic Acid into a tared, clean, glass, beaker. Record weight in grams, (i.e. .220g)
Add 50 mL of 5% H
2SO
4to beaker and place in ice bath and start magnetic stirring.
Add three drops of Ferroin indicator to beaker (this will turn the solution to a salmon color)
Titrate with .1N Ceric Ammoniun Sulfate until the disappearance of the salmon color.
Add 10mL of 10% Potassium Iodide Solution to beaker.
Add 3mL of Starch Indicator Solution to beaker.
Titrate with .1N Sodium Thiosulfate until the appearance of an orange solution (record volume of Sodium thiosulfate used)
I usually perform the assay in duplicate, (if you are anal enough to go this far you might as well do it correctly)
Calculation:(mL of Sodium Thiosulfate)(Normality of Sodium Thiosulfate)(3. =
%
grams of sample
Example:Weight of 35% Commercial PAA: .220g
Burette reading at start: 8
Burette reading at finish: 28.5
Total mL of Sodium Thiosulfate used: 20.5
(20.5)(.1)(3. = 35.4% Peracetic Acid
.220