Requirements stated in USP <788>, EP 5.1 and JP 17 demand that injectable solutions are effectively monitored for microcontamination, specifically non-soluble particulates. Potential sources of particle contamination include the manufacturing environment, personnel, and packaging components. In this blog, we examine the history of particulate control in injectables and counting solutions that meet standards set by pharmacopoeias.
Particle counters use lasers which provide intense light to count very small particles. All lasers have a finite lifetime, but that lifetime can be extended or shortened based on how the laser is used. Your cost of ownership will decrease if the laser lasts longer.
Most Optical Particle Counters use a light source to illuminate a sample volume, an optical system to collect the particle’s scattered light pulse, a process to convert the scattered light into an electrical signal, and electronics to correlate particle size with the scattered light pulse. While the specific design varies greatly between manufacturers (and while the instruments vary with different sensitivity and flow rates), the fundamental principles of optical particle counter operation are quite similar across the industry.
When monitoring larger size particles, extinction optical particle counting is the typical method used for accurate results. The refractive index difference between microcontaminants and the liquid media being measured can be explored in an effort to determine the related extinction response. At submicron particle ranges, the index contract between a particle and the liquid media is important. The interplay of refractive index contrast and particle size analysis in liquids can be explored and described with the aid of Mie theory.