Particle Counting & Sizing Using Light Obscuration in Compliance with USP 787, 788, & 789

The light obscuration method is a high-resolution analysis technique for particle counting and sizing used in various pharmaceutical applications. In this method, a solution containing particles is drawn through a tube by a syringe. Light from a laser is shined through the tube onto a detector. When a particle passes through the laser light, it casts a shadow onto the detector. The corresponding drop in signal from the detector is then used to determine the equivalent circular diameter of the particle, and the number of drops is counted to determine the number of particles in the sample. A multi-point calibration ensures accurate counts across a wide range of particle sizes.

Ebatco’s NAT Lab is equipped with a Beckman Coulter HIAC 9703+ Light Obscuration Particle Counter, which is purpose-built for parenteral product testing and allows for quick, automated particle counting in compliance with USP 787, USP 788, and USP 789. The instrument can be configured to use different volume and flow rates, which allows for testing of small and large volume injections. SOPs can be programmed directly into the machine, allowing for easy availability of regulatory standard testing and automatic PASS/FAIL detection.

Typical Experimental Results

Particle distribution for a mixture of 10 and 20 µm latex spheres.

Syringe Wash Test in reference to USP 787 with Different Types of Syringes.

Applications

Instrument: Beckman Coulter HIAC 9703+ Liquid Particle Counter

Instrument Key Specifications

For more information, please read our application notes:
All application notes can be found here

USP Standards