Why does the "Pharmacopia" stipulate that the photoresistive liquid particle counter is used to measure the particles in the liquid medicine? When measuring What aspects should be paid attention to?

Both the United States Pharmacopoeia and the Chinese Pharmacopoeia use the photoresist method to detect particle items. This is because the photoresist method detects particles. Measuring particles has the characteristics of simplicity, rapidity and high sensitivity. Compared with the photoresist method, the resistance method is frequently operated and small .The orifice tube is easy to block, the stability of the instrument is poor, the sensitivity is low, and the equilibration time is too long.

  When measuring, it should be noted that the concentration of the suspension should not be too high, otherwise there will be overlap and continuous counting of particles passing through the optical path.

affect the counting results. In addition, stirring should be able to suspend the particles without generating air bubbles, otherwise the air bubbles .  Also counted as "grains".