methyl_ethyl (Guardian) 02-23-04 12:55 No 490576 |
Peracetic Acid Titrative Assay (Rated as: good read) |
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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%H2SO4 Cracked 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% H2SO4to 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)(3.8) = % 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)(3.8) = 35.4% Peracetic Acid .220 Unipolar Mania, It's good for life... |
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terbium (Old P2P Cook) 02-24-04 04:54 No 490731 |
Peracid titration. | |||||||
I don't understand the point of titrating with ceric ion. When I used to determine peroxides we would just add iodide and titrate the liberated iodine with thiosulfate and starch indicator. All those moments will be lost in time, like tears in rain. |
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methyl_ethyl (Guardian) 03-03-04 05:02 No 492553 |
RE: Ceric Sulfate | |||||||
I don't understand the point of titrating with ceric ion. When I used to determine peroxides we would just add iodide and titrate the liberated iodine with thiosulfate and starch indicator. Regarding the titration with Ceric Sulfate: The point of titrating with ceric sulfate first is the titration of H2O2. Since we are interested in the percent peracetic acid, it is not pertinant to us how much free hydrogen peroxide is present. If we we wanted to know how much Hydrogen Peroxide was present in the solution we could derive that from: mL of Ce(SO4)2 X Normality X .017 X 100 = % H2O2 sample weight The assay I describe originally is an assay for the iodometric determination of percent peracetic acid. I believe the method I described is the best method for accurately determining the % Peracetic Acid in Solution. H2O2 + 2Ce(SO4)2 ------> O2 + Ce2(SO4)3 + H2SO4 CH3COOOH + 2 KI + H2SO4 -----> I2 + K2SO4 + H2O + CH3COOH I2 + Na2S2O3 -----> 2 NaI + Na2S4O6 I hope this helps explain the need to titrate the free hydrogen peroxide first before quanitifying the percent peracetic acid. If not please inquire further about the validity of the assay and I will try to explain / justify further. Unfortunately I have not had time to log onto the hive as often as I would like, therefore my response will more than lilkely not be in a timely manner. Sorry.... regards, m_e Unipolar Mania, It's good for life... |
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