DLS Particle Size Analyzer: Overview and Testing Steps

Dynamic Light Scattering (DLS), also known as photon correlation spectroscopy or quasi-elastic light scattering, is a technique used to measure the size distribution of particles (such as proteins, polymers, nanoparticles, etc.) in a solution. In a DLS experiment, a liquid sample is illuminated by a laser beam, and the particles in the solution cause the laser to scatter. These scattered photons are captured by a detector at a specific angle. Due to the Brownian motion of particles in the solution, the intensity of the scattered light fluctuates over time. By measuring these intensity fluctuations, the size of the particles can be calculated.

 

Steps of Dynamic Light Scattering Particle Size Analysis

1. Sample Preparation

(1) Clean the sample bottle or test cell to ensure no impurities, dust, or scratches.

(2) Prepare the sample solution. Pay attention to the degree of dilution, the choice of solvent, and the uniformity of the sample. The sample should fully represent the substance to be analyzed and should avoid bubbles and aggregation.

 

2. Instrument Calibration

Follow the requirements of the instrument for system calibration, including temperature setting, software setting, and initial calibration by using standard particles.

 

3. Sample Loading

Load the prepared sample solution into the test cell or small sample vial. Ensure there are no bubbles, as bubbles can interfere with the measurement results.

 

4. Parameter Setting

Set appropriate parameters on the DLS instrument, such as measurement time, temperature, and laser intensity. These parameters may need to be adjusted based on the characteristics of the sample.

 

5. Measurement

Start the measurement. The instrument records the time change of the scattered light intensity, and the size of the particles is determined by analyzing these data.

 

6. Data Analysis

(1) Use instrument software to analyze the data. DLS usually provides information on particle size distribution, including average particle size and distribution width.

(2) For complex samples, multiple measurements may be needed, or different analysis models may be used to obtain accurate results.

 

7. Results Interpretation

(1) Interpret the obtained particle size distribution results. Consider whether there is aggregation, whether the experiment needs to be repeated, or whether further sample treatment is needed.

(2) Prepare a measurement report, including experimental conditions, parameter settings, and analysis results.

 

After the measurements are finished, remember to clean the sample vial and test cell, and maintain the instrument to ensure accuracy and reliability for the next use.

 

Precautions

1. The concentration of the sample should not be too high to avoid data distortion due to multiple scattering or interactions.

2. Avoid bubbles entering the sample, as they can affect the results.

3. Ensure the equipment is clean to avoid any contaminants affecting the results.