Lab Report - Particle Size Analysis (Metasizer and Zetasizer)

INTRODUCTION
Particle size analysis is a laboratory technique to determine the size range, average or mean size of
particle in a sample. Eg, in powder or liquid.

This can be perform with a variety of techniques or methods. Particle size analysis methods can be categorized based on several different criteria :-
-Size range of analysis
-Wet or dry methods
-Manual or automatic methods
-Speed of analysis

Example of particle size analysis methods in:-
-Sieve method
-Microscope method
-Coulter counter
-Laser light scattering method
-Dynamic light scattering method
-Sedimentation method

OBJECTIVE
-To able to use the instruments to analyse particle size.
-Able to use different methods of particle size analysis to determine particle size and size distribution of different products.
-Able to analyse and interpret the data obtained in the experiment.
-To determine the best method to measure particle size for each product.

MATERIALS 

Gaviscon Suspension (Sample B)

Cod Liver Oil emulsion (Sample C)

Polystyrene nanoparticles from Malvern, U.K. (Sample D)

Distilled water

METHODS 
1.  The Malvern Zetasizer or Mastersizer  was powered up.

      2.  The software was launched.

      3. The cell was loaded and the measurement was run.  

      4.The results were viewed.

      5. The cell was removed from the machine.

      6. The cell washed

RESULTS

1.  Fill in the table below:

No.	Particle size, µm			Size Distribution
	Cod Liver Oil®	Gaviscon®	Polystyrene nanoparticles	Cod Liver Oil ®	Gaviscon®	Polystyrene nanoparticles
1.	21.105	35.969	105.9	0.645	1.01	0.024

2. Draw the shape of peak(s) obtained for each sample. Give your comments.

Comments:

            As the three samples were analyzed using MalverZetasizer and Metasizer, the result show that the largest particle size is the polystyrene nanoparticles which is the value is 105.9µm. while the smallest particle size is the Cod Liver Oil suspension with 21.105µm.

            In size distribution parameter, the largest value belongs to the Gaviscon suspension with 1.01. While polystyrene nanoparticles has the smallest size distribution with 0.024.

DISCUSSIONS 

1. Describe TWO (2) parameters which should be provided when using Malvern Zetasizer® and         Mastersizer®.

Two parameters that should be provided when using Malvern Zetasizer and Mastersizer are particle size and size distribution. Particles size is important because it will influence stability of suspension, reactivity or dissolution rate and viscosity. While size distribution is important because in light scattering method it will give volume weight distribution. Volume of particle will be contributed by each of the particle which is equivalence to the mass if the density uniform. Thus, relative contribution will be proportional to size of distribution.

2. Discuss the appropriateness of using the above methods to analyse the samples.

The Mastersizeruses the technique of laser diffraction to measure the size of particles. It does this by measuring the intensity of light scattered as a laser beam passes through a dispersed particulate sample. This data is then analyzed to calculate the size of the particles that created the scattering pattern.The method can be used on all powders containing less than 10% fat.A typical system is made up of three main elements which are optical bench, sample dispersion units and instrument software.For the optical bench, a dispersed sample passes though the measurement area of the optical bench, where a laser beam illuminates the particles. A series of detectors then accurately measure the intensity of light scattered by the particles within the sample over a wide range of angles.Then for the sample dispersion units (accessories).Sample dispersion is controlled by a range of wet and dry dispersion units. These ensure the particles are delivered to the measurement area of the optical bench at the correct concentration and in a suitable, stable state of dispersion. Third one is Instrument software which controls the system during the measurement process and analyzes the scattering data to calculate a particle size distribution.

3. Suggest another method to measure particle size, if both methods are not suitable to analyse particle size any of the samples.

Another method to measure particle size is by using microscope. Primary particles are vacuum dispersed in air or liquid on object glass prior to image analysis and magnified up to *1000. Microscopy and digital image analysis can be used for Determination of particle size distribution.Particle Analytical applies  microscopes equipped with objectives for 40 to 1000 times magnification and a macroscope with objectives for 3.5 to 90 times magnification. A digital camera enables live recording of images. The images are processed with Image-Pro Plus software from MediaCybernetics. The measurement of the particles is thus operator independent and reproducible. All images are stored for complete documentation. The primary particles are dispersed in liquid or in air by vacuum dispersion on object glass prior to image analysis.

4. Explain the principle of Malvern Mastersizer® and Zetasizer® operation on measurement of particle size. (Please include the Frounhofer and Mie Theory).

     Laser diffraction measures particle size distributions by measuring the angular variation in intensity of light scattered as a laser beam passes through a dispersed particulate sample. Large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles. The angular scattering intensity data is then analyzed to calculate the size of the particles responsible for creating the scattering pattern, using the Mie theory of light scattering. The particle size is reported as a volume equivalent sphere diameter.

5. Describe the advantages of using the above methods in analysing particle size.

Malvern Mastersizer uses laser light scattering method. Advantage of using this method are:-

•   It has a wide and dynamic range in measuring particle size, between approximately 0.1 and 2000 microns.
•   This technique allows for the whole sample to be measured by analyzing the diffraction of light when it pass through every particle in the sample.
•   Results can be obtain in a very short time.
•   Technique is repeatable so to obtain the most accurate measurements.

On the other hand, Zetasizer uses dynamic light scattering method. The advantage of this method includes:-

• Provide an accurate, reliable and repeatable particle size analysis in a short time
• Simple or no sample preparation, high concentration, turbid samples can be measured directly.
• Simple set up and fully automated measurement.
• Size measurement of sizes < 1nm.

CONCLUSION

Based on the objectives, we are able to know how to use instruments in analyzing particle size and also use different methods of particle size analysis to determine particle size and size distribution of different products. From the results, we are able to interpret the data obtained.