1Dynamic light scattering instrumentPre-operation preparation

Environmental Requirements

Choose a stable, dry, and temperature suitable location to install the instrument, ensuring that the bottom of the instrument is in smooth contact with the ground, the light path is perpendicular to the ground, and the bottom of the instrument is at least 50cm above the ground.

Avoid air flow, vibration, and strong electromagnetic interference sources (such as large motors and high-frequency equipment) to ensure a stable measurement environment.

sample preparation

Dispersion: The sample should be evenly dispersed in a liquid medium to avoid aggregation or precipitation.

Concentration control:

Protein samples: The recommended concentration for 14kDa protein is 1mg/ml, and the recommended concentration for 28kDa protein is 0.5mg/ml.

Other samples: Adjust the concentration according to the particle size to avoid multiple light scattering (high concentration) or weak signal (low concentration).

Remove bubbles: The sample needs to be centrifuged at 12000rpm for 10 minutes, and the supernatant should be taken to avoid bubbles affecting the measurement.

Sample size: The sample pool has a capacity of approximately 14 μ l. It is recommended to prepare 20 μ l of sample to ensure full filling.

Instrument inspection

Check if the power supply, connecting wires, and optical system are functioning properly, ensuring that components such as the laser, detector, and temperature control module are securely connected.

Preheat the instrument for 10-15 minutes and measure after the system stabilizes.

2、 Operation steps

Startup and software connection

Connect the power supply and turn on the host, temperature control module, and computer power in sequence.

Run measurement software (such as Zetasizer, IRSoft, etc.), click "Connect" or "Hardware" to establish a connection between the software and the instrument, confirm the successful connection, and the icon will turn green.

Sample loading

Rinse the micropipette and sample tank with water to avoid contamination.

Slowly inject the sample into the sample cell using a micro pipette, avoiding scratching the bottom or side walls of the cell with the needle.

Place the sample pool into the sample chamber, ensuring that the arrow is facing towards you, and cover the sample chamber lid.

Parameter Settings

Instrument parameters:

Laser intensity: Adjust according to sample concentration (high concentration samples need to reduce power to avoid signal overload).

Temperature: Set the measurement temperature (such as 25 ℃) and maintain a constant temperature for 120 seconds to stabilize the sample temperature.

Solvent parameters:

Enter the refractive index (RI) and viscosity of the solvent, which need to be updated in real-time as the temperature changes.

Sample parameters:

Enter the refractive index (RI) and absorption index (Absorption) of the sample. For protein samples, select the "Material" type and enter the corresponding parameters.

Measurement parameters:

Measurement time: Set according to the stability of the sample (such as measuring continuously for 3 times, each time for 120 seconds).

Scattering angle: Usually 90 ° (for small particles) or 173 ° (for large particles) is selected.

Data filtering: Set the deviation range (such as Baseline=1 ± 0.003) to filter out abnormal data.

data collection

Click "Start" or "Measure" to start measuring, and the instrument automatically records the changes in scattered light intensity over time.

Avoid touching the instrument or sample cell during the measurement process to prevent optical path deviation.

The red data represents values that exceed the set range and are not used for analysis.

data analysis

Particle size distribution: The software automatically calculates the hydrodynamic radius (Rh) and polydispersity index (PDI) to generate particle size distribution maps (such as log normal distribution and MSD multisize distribution).

Correlation function: Analyze the relationship between light intensity fluctuations and time, and evaluate sample uniformity.

Data export: Save in CSV, Excel, or PDF format for further processing or report generation.

IIIDynamic light scattering instrumentPost operation maintenance

Cleaning and Maintenance

After the measurement is completed, immediately rinse the sample tank with water, blow dry it, and store it to avoid residual sample contamination.

Regularly clean optical components (such as laser windows and detectors) using dust-free cloths or specialized cleaning agents.

Check if there are any debris or dust inside the instrument, and keep the dry tube of the optical path system in a moisture absorbing state (if moisture is absorbed, it needs to be dried and regenerated).

Calibration and Verification

Regularly use standard particles (such as polystyrene latex) for calibration to ensure measurement accuracy.

Check if the instrument connection is normal, if all components are securely installed, and conduct electromagnetic compatibility testing.

Storage and Security

When the instrument is not in use, store it in a dry, ventilated, and non corrosive gas environment, disconnect the power supply, and cover it with a dust cover.

Avoid contact with hazardous chemicals to prevent safety accidents.