USP <787> Subvisible Particulate Matter in Therapeutic Protein Injections

The new USP <787> SUBVISIBLE PARTICULATE MATTER IN THERAPEUTIC PROTEIN INJECTIONS test can be used as an alternative to USP<788>. USP <787> is meant for therapeutic protein injections, making changes for smaller test product volumes and smaller test aliquots. Here is a summary of how to test a sample following the new USP 787 procedure:

Follow the same standardization steps as described in USP <1788>

• Volume accuracy
• Flow rate
• Sensor resolution
• Calibration
• Count accuracy

Two system controls tests are recommended

• Blank test: measure five aliquots of degassed particle-free water, the count must be less than 1 particle/mL > 10 µm.
• System suitability verification; analyze the USP particle count reference standard and pass the count limits

Sample preparation

• If there is enough volume test individual units
• If the volume is too small, mix units and combine the contents to obtain the required volume (typically 0.2-5.0 mL)
• Degas the sample and gently mix again


• Analyze four aliquots
• Count the particles in the size range of interest, including >10 & 25 µm
• Disregard the first result and average the second two

Pass/Fail criteria

If the container volume < 100 mL;  less than 6000 particles/container > 10 µm and 600 particles/container > 25 µm

If the container volume > 100 mL; less than 25 particles/mL > 10 µm and 3 particles/mL > 25 µm. Also not exceed the per container limits for the < 100 mL  criteria above.

The AccuSizer FX Nano system is ideal system for performing the USP <787> test for the following reasons

• Passes all standardization and system suitability tests
• Sensitivity down to 0.15 µm
• Higher concentration limit
• Accurate sample volume down to 250 µL

Aggregated IgG protein before and after filtration as measured on the AccuSizer FX Nano









Download the Protein Aggregation application note AN 708.