Dr. Fukuda et al. from Towa Pharmaceutical Co., Ltd. in Japan developed a test method for simultaneously high-sensitivity testing of 10 typical small amines, precursors of nitrosamines, in more than 200 drug substances. This is known as " the Towa Amine Approach" in Japan. This method realizes good separation and accuracy of amines in many APIs by connecting two different types of columns, an ODS column with anion and cation exchange and another ODS column, and controlling pH and dissolution with three mobile phases. It’s fantastic!
https://pubs.acs.org/doi/10.1021/acsomega.4c06293
