Overview
EN ISO 5810:1994 specifies a potentiometric method for the determination of chloride content in starches and derived products. The method uses a standard volumetric silver nitrate (AgNO3) solution to titrate a solution or suspension of the sample while monitoring potential change. The procedure is not applicable to cationic starches and to amyloids soluble when cold, because high viscosity prevents correct stirring when titrating.
This method is widely used in laboratory quality control and compositional analysis where accurate chloride measurement is required for regulatory compliance and product specification.
Key Topics
- Principle: Potentiometric titration of a sample solution or suspension with a standard AgNO3 solution; the end-point is taken at the inflection point of the potentiometric curve.
- Reagents: Concentrated nitric acid and standard volumetric silver nitrate solutions (commonly 0.05 mol/L or 0.02 mol/L are cited).
- Apparatus:
- Potentiometer or pH meter with millivolt scale
- Silver/silver chloride indicator electrode and suitable reference electrode
- Variable-speed stirrer, burettes, pipettes and analytical balance
- Sample preparation: Mix sample to homogeneity. Transfer the selected test portion to a titration beaker with 100 mL water and stir to form a solution or suspension; insoluble products require extended stirring.
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Test portion guidance (example masses):