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Physical stability assessment of pharmaceutical emulsions by Diffusing wave spectroscopy (DWS) (CAT#: STEM-MB-0853-WXH)

Introduction

Emulsions are broadly used in pharmaceutics either as intermediate products or as final dosage forms. Such disperse systems are only kinetically stabilized and therefore early detection of physical instability is highly desirable. DWS provides a highly attractive method for stability analysis of pharmaceutical emulsions because it requires only low sample volumes, is rapid and non-invasive.




Principle

Diffusing-wave spectroscopy (DWS) is an optical technique derived from dynamic light scattering (DLS) that studies the dynamics of scattered light in the limit of strong multiple scattering. DWS is able to give information about the local dynamics of particle dispersion in a highly turbid medium. It has been widely used in the past to study colloidal suspensions, emulsions, foams, gels, biological media, and other forms of soft matter. If carefully calibrated, DWS allows the quantitative measurement of microscopic motion in a soft material, from which the rheological properties of the complex medium can be extracted via the microrheology approach.
The technique of DWS depends on the scattering of light from highly turbid suspensions. A sample of the suspension is illuminated by light from a laser and the incoming photons are multiply scattered. This scattered light is detected and subjected to autocorrelation analysis.

Applications

• Diffusing Wave Spectroscopy (DWS) is an advanced light scattering technique, which is primarily applied for microrheology and particle sizing.
• DWS has been applied in biomedical and clinical areas, especially in monitoring cerebral blood flow (CBF).

Procedure

1. Sample Preparation
2. Diffusing Wave Spectroscopy Testing
3. Data analysis

Materials

• Diffusing wave spectroscopy (DWS) instrument
• DWS RheoLab