Methods for Product Assay Methods for Residual Peroxide Determination Additional Information

Ceric Sulfate Titration

Principle

Hydrogen peroxide content is determined by titrating with standardized ceric sulfate to pale blue endpoint using ferroin indicator.

Scope of Application

This procedure is appropriate for characterizing 1-30% hydrogen peroxide content in either aqueous solutions or equilibrium mixtures (e.g., Caro's acid or peracetic acid). Higher concentrations may be determined by diluting the sample.

Interferences

None likely.

Safety Precautions

Please consult Safety and Handling guidelines, particularly as relates to personal protective clothing and footware. Neoprene or PVC aprons are recommended, as are monogoggles and neoprene rubber gloves. Sample bottles containing H2O2 should not be stoppered, but rather vented or covered loosely with aluminum foil or paraffin film. Solutions withdrawn from a sample bottle should not be returned to that bottle but should be flushed down the drain with plenty of water. Any spills should be flushed with water immediately as should any combustible materials which come into contact with the product. Do not use adsorbent media to clean up H2O2 spills.

Reagents

1. Ceric Sulfate (0.1N). Standardized.
2. Ferroin indicator. Weigh 0.174 gms FeSO4. 7H2O into a 100-mL beaker. Add 25-mLs distilled water and stir to dissolve. Weigh out 0.37 gms of o-phenanthroline monohydrate and add to the ferrous sulfate solution. Stir to dissolve.
3. Sulfuric acid (1:19). CAREFULLY and with constant stirring add 50 mLs concentrated sulfuric acid (sp.gr.1.84) to 950 mLs distilled water.

Procedure

1. Measure 150 mLs of sulfuric acid into a 500 mL conical flask, and add sufficient crushed ice to maintain the temperature below 100 deg-C during the first titration.
2. Add 2 - 3 drops of ferroin indicator and titrate with ceric sulfate (0.1N) to a pale blue color.

3. From the chart below, weigh to within 0.1 mg a suitable mass of sample into a glass weighing bottle. Let the mass taken be W gms.

   Expected H2O2 Content (wt.%)	Suggested Sample Weight(gms)
   1 - 3	5 - 15
   3 - 10	1.5 - 4.5
   10 - 30	0.5 - 1.5

4. Add the weighed sample to the cold contents of the conical flask and mix.
5. Titrate with ceric sulfate to a blue end-point. Let the amount of titrant required be A mLs. Retain flask.

Calculation

Hydrogen Peroxide, wt.% = (A) x (N) x (1.701) / W
Where: N is the normality of ceric sulfate.