Abstract: Objective：To establish a laser light scattering method for the determination of particle size and distribution of dihydroartemisinin APIs. Methods：Samples were prepared to be a suspension with Tween 80 aqueous solution as the dispersant， by vigorously shaking it for 2 min and then ultrasonic processing it for90 s. A Malvem MasterSizer 3000 type laser size analyzer was used with a wet auto-sampler.Sample refractive index was 1.520， absorbency was 0.1， dispersant refractive index was 1.330， shading degree was 10%-25%， stirring speed was 1 500 r·min-1， sample measuring counts was 3， measuring time for background and samples were both 10.0 s. Results：Method validation results：The RSD(n=6) of repeatability for d(0.5) was 6.4%， for d(0.1) was 9.5% and for d(0.9) was 9.8%.The RSD(n=12) of intermediateprecision for d(0.5) was 8.0%， for d(0.1) was 15.3% and for d(0.9) was 11.6%. Robustness： Under the condition of different stirring speed(±10%) and different measuring time(±2 s)， the RSD for d(0.5) were all lower than 4%， for d(0.1) were all lower than 3% and for d(0.9) were all lower than 7%. Solution stability： Within 1 h of sample suspension and sample cell suspension were placed at ambient temperature for， the RSD for d(0.5) were all lower than 3%， for d(0.1) were all lower than 4% and for d(0.9) were all lower than 4%. All the method validation results complied with the requirements of USP<429>. The RSD of measuring results of 3 batches of samples for d(0.5) were all lower than 3%， for d(0.1) and d(0.9) were all lower than 5%， which demonstrated the results was accurate.Conclusion：The established method is simple in operation， accurate and precise， which is applicable for effective control of particle size and distribution of dihydroartemisinin APIs.
    

Key words: font-size:medium, ">Dihydroartemisinin；Laser light scattering method；Particle size；Method validation；USP<, 429>,