It’s no surprise that there are many technologies available to analyze subvisible particles. Particle sizing and characterization are critical components of many processes across a wide range of applications. For example:
- Municipalities monitor drinking water supplies to detect and quantify taste and odor causing algae.
- Pharmaceutical companies analyze particles in parenteral drug formulations to help ensure its efficacy and safety.
- Food and beverage companies use particle analysis to control the quality of their ingredients and end product.
- Ocean researchers use particle analysis to study and document microscopic life in the earth’s oceans.
The list could go on and on...
So, what is particle analysis anyway? It involves looking at a small portion of a substance (particle) and separating it into its components parts (analysis). The basic goal is to determine the constituents of a mixture.Typical measurements of particles that are of interest to scientists and engineers include, particle size distribution, count, shape and concentration. For simplicity, results of a particle analysis are typically reported graphically, with particle size plotted against some other variable. Particle size is often stated as equivalent spherical diameter (ESD), which is an estimated value based on the volume of the particle.
There are many ways to analyze particles. Manual microscopy and volumetric particle analysis are popular techniques. While seemingly straightforward for particle size, when shape and/or morphological data is needed, a more in-depth analysis is required to truly characterize a particle. Today, we’ll take a closer look at the FlowCam® dynamic imaging particle analysis (DIPA) system and its usefulness. Including:
- How dynamic imaging particle analysis works
- Direct particle measurements
- Data processing – filter & sorting
How Dynamic Imaging Particle Analysis Works
DIPA uses digital images to measure the size and shape for each particle. Essentially, the operator in classical microscopy is replaced by a computer to extract the information from the images.
The sample containing the particles streams by the microscope optics in the flow cell, and thousands of particle images are captured per second.
In order to freeze the moving particles in space, a strobed illumination source is combined synchronously with a very short shutter speed in the camera.
As each frame of the field of view is captured, the software, in real time, extracts the particle images from the background and stores them.
Direct Particle Measurements
In an imaging-based system, particle measurements are made directly from an image of the particle. Since the system’s optics are fixed and the magnification is known, distance measurements on the image can be directly converted to real distance measurements on the object.
No assumptions are made about a particle’s shape and multiple measurements are made for each particle. Plus, you can view the image, to ensure that the data is being properly interpreted. Common measurements include:
- Equivalent spherical diameter (ESD)
- Length, width, and aspect ratio
- Area and volume
- Circularity and elongation
- Edge gradient
- Intensity, average intensity, and sigma intensity
Data Processing – Filter & Sorting
The FlowCam DIPA system offers VisualSpreadsheet® software, which enables you to sort and filter your data based on any of the measurements (or combination of measurements) acquired for the particles. Then it displays the results in both tabular format and visually in the form of the particle images themselves.
You can interact with the scattergram created to quickly select particles of interest from any of the configurable graphs.
You can also build filters with the FlowCam to isolate particles of a particular type automatically in the sample.
Multiple filters can be created, saved, and reused, which allow you to separate a sample into its component parts based upon particle properties.
One filter type is a value filter. For example, you can choose particles within a specific size range that are long and skinny. The other type is a statistical filter, where you can click on several images that are of a particular type, and the software finds images similar to those selected.
The FlowCam VS series is ideally suited to a typical laboratory environment, and can be configured in a variety of ways to fit your specific needs and application.
We invite you to see the FlowCam difference. Send us your sample (we'll need at least 100 mL) and discuss your specific needs. Once received we'll analyze your sample and present you with a free report of the results.