Particle Size Distribution Analyses - Light Obscuration Photozone
Light Obscuration, also referred to as Photozone and Single Particle Optical Sensing (SPOS), is an analytical technique of high resolution capable of detecting a small percentage of outliers. It can also be used to obtain an overall size distribution, when operated with proper technique. An important consideration when choosing Light Obscuration is the concentration of the sample presented to the instrument. The sample must be in a dilute form (either as received or prepared by PTL) for analysis. The technology works by passing a dilute stream of particles in a liquid suspension between a light source and a detector. The light source in this case is a laser diode, which illuminates the individual particles in the stream and results in a shadow or blockage of light on the detector. This light blockage is termed obscuration. The detector measures this reduction in light intensity and using a calibration curve; processes the signal to determine the size of the particle. For smaller particles (i.e. approximately <2 µm) a light scattering detector measures the increase in light intensity scattered over an optimized range of predetermined angles. The signal is also counted as a single event, thus this technique is able to provide true particle counts as it analyzes individual particles. The results can be reported on a Number and/or Volume weighted basis, using the classic assumption of Equivalent Spherical Diameter.
Light Obscuration is another widely accepted particle sizing technique in many fields. Fields ranging from pharmaceuticals to hydraulic/lubrication applications can utilize the particle counting and sizing capabilities of Light Obscuration. The technique is recognized by the ISO, USP and ASTM for example as an appropriate method for measuring the size and number of particles in samples such as: injectables, ophthalmic solutions, industrial oil/lubricates and even dilute waste/process water studies. Numerous carrier fluids, both organic and inorganic can be used with the instrumentation. PTL has utilized Light Obscuration to solve numerous pharmaceutical and industrial problems for clients over the years.
Below is a list of the Light Obscuration instruments available at PTL. Please contact us to discuss if your sample and project could benefit by Light Obscuration analysis…
Particle Sizing Systems AccuSizer Model 770
Statistical analysis on a volume and number basis (lower detection limit 1µm)
Statistical analysis on a volume and number basis (lower detection limit 0.5µm)
Click here for a typical AccuSizer 770 sample report.
Particle concentration in a liquid suspension is charged additionally.
Click here to request a quote or for more information on Light Obscuration particle testing.
Industries Served
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Abrasives Serving the abrasive industry over the last 2 decades, the most common testing performed for this field is particle size and shape analysis. The world of abrasives can encompass a host of varying...
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Dietary Supplements Concurrent with the U.S. Food and Drug Administration’s final rule establishing regulations to require current good manufacturing practices (cGMPs) for dietary supplements, PTL can offer cGMP services...
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Environmental Testing Services Particle size, particle concentration and other physical characterization analyses are critical to many environmental applications. Regulatory agencies in the environmental sphere demand strict compliance...
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Medical Devices Advances in biomedical implant and device technology continue to present new challenges in the area of physical testing. Particle Size Distribution, Surface Area and Porosity measurement data are...
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Pharmaceutical Testing Services Supporting drug development with pharmaceutical testing is some of the most exciting work we do. As a premier cGMP contract service laboratory, PTL partners with pharmaceutical scientists to identify...
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Beauty / Cosmetics Testing PTL’s analytical staff has years of experience designing test methods and performing analysis for cosmetic, skin care, fragrance and personal hygiene samples. Whether your company needs a third...
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