著者

Nahoko Uchiyama Junko Hosoe Naoki Sugimoto Kyoko Ishizuki Tatsuo Koide Mika Murabayashi Naoto Miyashita Kengo Kobayashi Yoshinori Fujimine Toshiyuki Yokose Katsuya Ofuji Hitoshi Shimizu Takashi Hasebe Yumi Asai Eri Ena Junko Kikuchi Kohei Kiyota Kazuhiro Fujita Yoshinobu Makino Naoko Yasobu Yuko Yamada Yoshiaki Iwamoto Toru Miura Koji Mizui Katsuo Asakura Takako Suematsu Ai Kohama Yukihiro Goda

出版者

The Pharmaceutical Society of Japan

雑誌

Chemical and Pharmaceutical Bulletin (ISSN:00092363)

巻号頁・発行日

vol.69, no.1, pp.118-123, 2021-01-01 (Released:2021-01-01)

参考文献数

11

被引用文献数

10

---

Quantitative NMR (qNMR) is applied to determine the absolute quantitative value of analytical standards for HPLC-based quantification. We have previously reported the optimal and reproducible sample preparation method for qNMR of hygroscopic reagents, such as saikosaponin a, which is used as an analytical standard in the assay of crude drug section of Japanese Pharmacopoeia (JP). In this study, we examined the absolute purity determination of a hygroscopic substance, indocyanine green (ICG), listed in the Japanese Pharmaceutical Codex 2002, using qNMR for standardization by focusing on the adaptation of ICG to JP. The purity of ICG, as an official non-Pharmacopoeial reference standard (non-PRS), had high variation (86.12 ± 2.70%) when preparing qNMR samples under non-controlled humidity (a conventional method). Additionally, residual ethanol (0.26 ± 0.11%) was observed in the non-PRS ICG. Next, the purity of non-PRS ICG was determined via qNMR when preparing samples under controlled humidity using a saturated sodium bromide solution. The purity was 84.19 ± 0.47% with a lower variation than that under non-controlled humidity. Moreover, ethanol signal almost disappeared. We estimated that residual ethanol in non-PRS ICG was replaced with water under controlled humidity. Subsequently, qNMR analysis was performed when preparing samples under controlled humidity in a constant temperature and humidity box. It showed excellent results with the lowest variation (82.26 ± 0.19%). As the use of a constant temperature and humidity box resulted in the lowest variability, it is recommended to use the control box if the reference ICG standard is needed for JP assays.