FAQ - Liquid Particles

APSS 200 Parenteral Particle Counter

Question
If we set the data as counts per ml (normalized count), then the will the reading be interpreted as counts/ml directly? or what is the difference between raw count and normalized count?

Answer

Regarding an APSS-200 system with a LiQuilaz E20P sensor (2 -125 um)

The data you view is based upon one criterion: do you manufacture Large or Small Volume Injectables (the definition would follow either USP, EP or JP standards)?

Small Volume (SVI) settings need to be: Accumulative, Normalized to Counts per Container.

This is, you need to see particles of size X and larger and this will encompass all particles of that size, and the legislation allows for a certain maximum particles in a single dose, and in SVIs this is deemed to be a unit volume of a container. Now USP/EP will require several (>10) of these containers to be pooled and the SamplerSight software allows for this in the configuration. The difference between Normalized and Raw is that normalized will allow for minor tolerance in a fixed volume, so you could take a 5 mL sample and the results will be essentially an average of the total counts / total volume = counts per unit volume. This is critical for compliance. Raw counts are the actual particles in suspension that are seen during a sample run.

Example:

Sample = 5mL, total counts = 125

Raw counts = 125

Counts / mL = 25

Large Volume (LVI) settings need to be: Accumulative, normalized to counts per mL.

Again, all particles of size x and greater and now due to the volume of dosage the criteria is based upon /mL as it is unknown how much final solution will be delivered.

The environment for both USP and EP needs to be in a laminar flow cabinet, EP define and ISO5 limit. SamplerSight has a calibration wizard included and this again should be followed with the instrument in a laminar flow cabinet.

For more information on understanding results from liquid particle counters I suggest you purchase the book Understanding Liquid Particle Counters.