The ISO/TR 13097 outlines guidelines for the stability characterization of dispersions. The stability of dispersions is closely linked to its shelf life. The guideline specifies different methods to analyze the stability, one of them is the optical measurement of the backscattered and transmitted light.
ISO/TR 13097: Application and Use
The ISO/TR 13097 technical report provides guidelines for the stability characterization of liquid dispersions. Dispersions are suspensions, emulsions, foams, and combinations of these systems.
Stability can be described as the ability of a dispersion to resist changes such as:
- creaming or flotation
- sedimentation
- flocculation, agglomeration, coagulation
- aggregation
- coalescence
- phase separation
- Oswald ripening
- phase inversion
These changes are also called "destabilization phenomena".
The shelf life is defined 'as the lifetime of a product (food, medicine, inks, cosmetics, etc.) during which there are no changes or variations greater than allowed by the product specification'. This document is particularly important for manufacturers aiming to optimize the performance, quality, and longevity of liquid dispersions. The stability of dispersions is a crucial parameter in many industries, such as cosmetics, food, pharmaceuticals, agrochemicals, paints, and other material sciences.
ISO/TR 13097: Experimentation
Methods
According to the ISO 15989, a water contact angle measurement can be conducted with a Contact Angle Meter, or Goniometer, which must include the following components:
- Visual Observation: This method involves observing the sample over time for visual signs of instability. It can be subjective, requiring regular monitoring over long periods, and results may vary depending on the operator's judgement.
- Instrumental Methods:
- Optical methods to measure changes in dispersion by recording transmission and backscattering intensities of light.
- X-ray transmission and tomography
- Acoustic and electroacoustic spectroscopy
- Measurements of electrical properties
- Correlative methods
- Methods to accelerate the analysis of the long-term stability allow to analyze very stable dispersions in an accelerated manner. However, the report mentions that such methods often induce additional destabilization phenomena to the dispersion.
The MS 20 Dispersion Stability Analysis System from DataPhysics Instruments can be used for optical measurements of light transmission and backscattering.
Procedure and Calculation
It is recommended to test the dispersion in its original state. The report distinguishes two different kinds of analyses, the comparative analysis and the predictive analysis.
- The comparative analysis can be used for quality control purposes. A sample is thereby compared to a well-studied reference product, using the same method and criteria.
- The predictive analysis is used when one needs to establish the shelf life of an unknown product for recommended storage, display and usage conditions.
The ISO/TR 13097 was last updated in 2013.
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