Colloidal Stability Characterization

Our Platform for Stability Analysis

Alfa Chemistry strives to develop a standardized procedure to characterize those instabilities that affect the properties of colloids. Our technology platform has a variety of characterization methods to evaluate the stability of colloidal materials. Each method has its advantages and limitations. Our methods include but are not limited to:

• UV–vis Absorbance Spectroscopy
  Monitoring beam absorbance at specific wavelengths to study colloid stability by changing the effective beam absorbance over time.

Fig.1 The colloidal stability of the magnetic suspension in polar solvents:absorbance intensity changes with time^[2]

Limitations: Concentration measurements require calibration curve or other a priori information.

• Dynamic Light Scattering (DLS)
  By observing the scattered light, the particle size, molecular weight and zeta potential of the colloidal dispersion system were determined. The stability of the colloidal sample is reflected by the slight change in the detected average particle size.

Fig. 2 (a) Scheme of a light scattering setup. (b) Exemplary DLS data by the accompanying software. ^[4]S

Advantages: short detection time, small sample volume required, wide range of dispersants available for detection.

Limitations: Spherical, monodisperse NPs yield best results. Non-spherical particles approximated as spheres causing errors.

• Phase Amplitude Light Scattering(Zeta Potential)
  Limitations: Spherical, monodisperse colloidal particles yield best results.High electric fields can affect sample.
• Turbidimetry
  Limitations: Colloidal particles must not exhibit absorbance at detection wavelength. Accuracy lost at high colloidal particle concentrations.
• Nanoparticle Tracking Analysis(NTA)
  Limitations: Not suitable for high con- centrations of colloidal particles.
• Analytical Ultra Centrifugation (AUC)
• Gravimetric Analysis

Why us?

• Comprehensive and rich characterization methods
• Accurate test results and short cycle
• Advanced testing equipment
• Professional testing and analysis engineers

References

1. Jarray A, et al.Stearic acid crystals stabilization in aqueous polymeric dispersions. Chemical Engineering Research & Design. 2016, 110:220-232.
2. Lee S Y, Harris M T. Surface modification of magnetic nanoparticles capped by oleic acids: Characterization and colloidal stability in polar solvents. Journal of Colloid and Interface Science. 2006, 293(2):401-408.
3. Ray T R, et al. Quantitative Characterization of the Colloidal Stability of Metallic Nanoparticles Using UV–vis Absorbance Spectroscopy. Langmuir. 2015, 31(12):3577.
4. Falke S, Betzel C. Dynamic Light Scattering (DLS): Principles, Perspectives, Applications to Biological Samples[M]. 2019.

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