LimsPulse
Dosage-form testing

Liquid Particle Counter (Light Obscuration)

Counts and sizes sub-visible particles in injections by passing the liquid through a narrow light beam. Each particle casts a shadow whose size gives the particle size. Used for the USP <788> particulate matter test.

  • Pharmaceutical (parenterals)
  • Biotech
  • Medical devices
  • Industrial fluids
TROUBLESHOOTING

Common problems, causes and fixes

High blank counts
Likely causes
  • • Dirty glassware or water
  • • Contaminated sensor
  • • Poor environment
What to do
  • • Re-clean glassware; use freshly filtered water
  • • Flush the sensor with detergent then water
  • • Work in LAF and wear gloves
Counts falling between portions
Likely causes
  • • Bubbles settling or dissolving
  • • Particles settling
What to do
  • • Degas properly before running
  • • Stir gently during measurement
Very high counts at small sizes
Likely causes
  • • Air bubbles
  • • Product precipitating
What to do
  • • Degas and re-run
  • • Check product compatibility; consider the microscopic method
Count accuracy check fails
Likely causes
  • • Coincidence errors
  • • Wrong volume
  • • Sensor drift
What to do
  • • Check dilution
  • • Verify syringe volume
  • • Recalibrate the sensor
In LimsPulse · Calibration Management

Keep every Liquid particle counter in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how