The purpose of this study was to develop monodispersed polystyrene particles as certified reference materials in accordance with the ISO 17034: 2016 and the ISO Guide 35. It can play a significant role especially during the COVID-19 pandemic since several covering items such as filtering facepiece respirators or medical masks must be investigated for the quality of operation by various sizes of polystyrene. The polystyrene particles were prepared in-house by National Nanotechnology Center (NANOTEC) using polymerization of styrene. Each batch was preliminary check for distribution, aggregation and averaged size by using dynamic light scattering. Then polystyrene particles were prepared to 1% solid suspension in deionized water for homogeneity testing, stability assessment and characterization using transmission electron microscope with ImageJ software. The 100 nm polystyrene as an example has been successfully synthesized fulfilled the criteria of size deviation from nominal value less than ± 10 nm and polydispersity index less than 0.05. Then, the particle size of polystyrene was statistically analyzed for screening test with the results of the coefficient of variation less than 10%. Stability assessment consisting of short-term stability testing with three different temperatures and long-term stability testing within 6 months observed was carried out. The results of short-term and long-term stability were presented within the maximum acceptable. The homogeneity tests for within bottle standard deviation and between bottle standard deviation were performed with randomly sampling. The results of homogeneity tests satisfied the criteria and therefore assigned the value as the certify value. Consequently, the certify value of 105.5 ± 4.6 nm of monodispersed polystyrene particles has been successfully developed as Thailand reference materials which were similar level of quality and accuracy to the standard commercial products.

本研究的目的是根据 ISO 17034: 2016 和 ISO 指南 35 开发单分散聚苯乙烯颗粒作为认证参考材料。它可以发挥重要作用，尤其是在 COVID-19 大流行期间，因为过滤面罩等几个覆盖项目呼吸器或医用口罩必须通过各种尺寸的聚苯乙烯进行操作质量调查。聚苯乙烯颗粒由国家纳米技术中心 (NANOTEC) 内部使用苯乙烯聚合制备。使用动态光散射对每批产品的分布、聚集和平均尺寸进行初步检查。然后将聚苯乙烯颗粒制备成 1% 固体悬浮在去离子水中进行均匀性测试，使用带有 ImageJ 软件的透射电子显微镜进行稳定性评估和表征。以 100 nm 聚苯乙烯为例，已成功合成，满足尺寸偏离标称值小于 ± 10 nm 和多分散指数小于 0.05 的标准。然后对聚苯乙烯的粒径进行统计分析，进行筛选试验，结果变异系数小于10%。进行了由三种不同温度下的短期稳定性测试和观察到的 6 个月内的长期稳定性测试组成的稳定性评估。短期和长期稳定性的结果都在可接受的最大值范围内。瓶内标准差和瓶间标准差的均匀性检验采用随机抽样的方式进行。同质性测试的结果满足标准，因此将该值指定为认证值。因此，105.5 ± 4.6 nm 的单分散聚苯乙烯颗粒的认证值已成功开发为泰国标准物质，其质量和准确性水平与标准商业产品相似。