Determination of Activie Chlorine in detergent

The REX Ti-50 Automatic Potential Titrator allows quick and simple determinations of the activie chlorine of detergent. 

Active chlorine is a compound with bacterial and virus inhibitory properties, usually found in compounds such as sodium hypochlorite (NaOCl) or calcium hypochlorite (Ca(OCl)₂). In cleaning and disinfection products, active chlorine is particularly preferred for the following reasons:

• Destruction of Microorganisms: Active chlorine disrupts the cell wall of microorganisms such as bacteria, viruses and fungi and provides hygiene by killing them.
• Bad Odor Eliminating Feature: Active chlorine provides effective deodorization, especially by oxidizing organic substances that create bad odors.
• Rust and Stain Removal: Active chlorine can prevent metals from oxidizing and help remove some stubborn stains.
• Water Disinfection: In domestic, commercial and industrial cleaning products, activated chlorine is commonly used for disinfection of water.

Determination of active chlorine in cleaning products is carried out to ensure the effectiveness and safety of the product. 

1. Standard Reference

ГОСТ 32386-2013 Товары бытовой химии. Метод определения активного хлора 

GB/T 13173-201 Surface active agents——Test methods for detergents

2.  The Principle

The determination of free chlorine in bleach is possible by a redox titration. The most common and successful method for use in high schools involves taking the sample of bleach converting the hypochlorite ion (ClO^-) to iodine (I₂) by the addition of KI and then titrating the iodine with standardized sodium thiosulfate solution. 

3. Recommended Configuration

1. Ti-50 Automatic Potential Titrator 

• Range：(-2000.00~2000.00) mV
• mV Accuracy：±0.03% or ±0.2mV
• 1 extra burette driver can be installed (optional).
• Replaceable burette with high-accuracy (10 ml or 20 ml selectable).
• Support acid-base titration, non-aqueous aqueous phase titration, constant titration, REDOX titration, precipitation titration, complexation titration
• Support the following titration modes: DET (dynamic equivalence point titration), MET (monotone equivalence point titration), SET (Preset Endpoint Titration) and MAT (manual titration).
• Titration methods, curves and results are displayed in detail
• Includes 213-01 platinum electrode and 217-01 reference electrode

      

      2. Anti-diffusion capillary

      3. Electrodes

•  213-01 Platinum electrode
•  217-01 Reference electrode（The filling solution needs to change to saturated Sodium nitrate solution）

Model	213-01
Name	Platinum electrode
Connector Type	BNC(Q9)
Sensor material	Glass
Dimensions	Φ12×120mm
Measuring unit material	Platinum
Working Temperature	5~50 ℃
Application	REDOX Titration

Model	217-01
Name	Reference electrode
Type of electrode	Saturated double junction calomel electrode
Connector Type	U shape terminal
Fill Solution	Saturated KCl solution (inner solution) + solution (Flexible choose)
junction material	ceramic
Sensor material	Glass
Dimension	Φ12×120 mm
Working Temperature	5~55 ℃

 

4.Procedure:

• Weigh 1g of the foaming detergent (accurate to 0.001g), dissolve it in distilled water, and transfer it to a 250 mL volumetric flask. Add water to the flask until the mark is reached, and mix well.

Note: Adjust the amount of the sample to be weighed according to the content of available chlorine.

• Add 10 mL of 2 mol/L sulfuric acid, 10 mL of 100g/L potassium iodide solution , and 5.0 mL of the mixed detergent to the iodine bottle. The solution will turn brown, cover the bottle, shake well, add water to the rim of the iodine bottle to seal it, and place it in the dark for 5 minutes (for the parallel sample).
• Use the 0.05mol/L sodium thiosulfate standard titration solution to titrate the free iodine.
• Titrate directly with 0.05mol/L Na2S2O3 solution to a single exothermic endpoint.

5.Titration Setting

• REDOX titration
• Sample: DET (dynamic equivalence point titration)

 

6. Titration curve