Monitoring Particulate Contaminationin Medical Devices


Mark Bumiller give a recent presentation on Nanoparticles in Drug Delivery, he has now produced a Application Note on the use of Accusizers for Monitoring Particulate Contamination in Medical Devices.

Read the Article here

A detailed knowledge of the PARTICLE size distribution important in solid oral drug products such as tablets, semi-solids (suspensions) and sterile liquid products)– impacting on heterogeneity, transport and efficacy , and as a critical quality.

There are two main approaches particle sizing and particle counting. Much has been made that many particle sizing methods are ensemble techniques, inferring particle size from the interaction of a population particles with a physical processes, i.e. scattering of light.  There have been heated arguments over the relative capabilities of these methods compared to individual particle characterization such as particle counting, which can distract from the real purpose of characterization.

In considering what is required it is best to consider a particles population of being like football crowd. Ensemble methods picture the whole crowd, from it you can determine which team they support and probably the current score. However in order to determine it is necessary to take a picture of each individual fan.

There are  wide range of techniques are available to determine particle size distribution; however Laser diffraction is the most popular particle sizing method today and universally used,. This is due to ease of use and proven precision. Laser diffraction is an ensemble particle sizing technique.

Not all particle size needs are met by laser diffraction. There is a limit of detection problem where up to 1to 3% by volume of large particles within the tail of a particle distribution can go undetected, i.e. small quantities of outsized or foreign particles.

Accusizer is a single particle optical counter (SPOS) combined with particle sizing. Counting and sizing is achieved by a combination of light extinction (1.5 to 400 μm) and light scattering (below 1.5 μm). An auto dilutor to automatically finds’ the optimum measurement particle count rate, while making the instrument easier to operate.

A counting technique such as SPOS will give a number weighted distribution where each particle is given equal weighting irrespective of its size. This is useful where knowing the absolute number of particles of a given size is important – in foreign particle detection.

Although ensemble techniques are frequently faster than counter or single particle techniques, counting enables; a wide size range; the counting individual particles and the unique ability to detect very small numbers of contaminants or outliers.

The Accusizer offers high size and number resolution and the capability to detect extremely small qualities of out of spec particles which is critical in some applications. It can do this quickly and with high confidence and accuracy.