Objective: To propose updates and amendments for the nitroglycerin tablets quality in the Chinese pharmacopoeia 2020 due to the failure of effective separation of 4 known impurities and nonseparation of free nitrate ion and excipients.
Methods: Related substances were analyzed using gradient elution by HPLC, and free nitrate ion was determined on SAX column by different HPLC method.
Results: Using the improved method to test the related substances and free nitrate ion of nitroglycerin tablets,the content of the maximum individual impurity were not more than 0.5%, the total content was not more than 2.4% and the content of free nitrate ion was not more than 6.3%.
Conclusion: The improved method is accurate and feasible. It provided a reference for the updates and amendments of the quality standard of nitroglycerin tablets in the Chinese Pharmacopoeia 2020.

Objective:To determine the relative correction factor of pre-vitamin D and simplify the calculation method of vitamin D assay.Methods:By studying the calculation method of vitamin D content in drug standards of various countries,HPLC was used to determine the relative correction factor of pre-vitamin D,and the influencing factors of determination were investigated.Results:The relative correction factors of pre-vitamin D at 254 nm and 265nm wavelength were determined by statistical analysis of 7 laboratories in China.Conclusion:Using the pre-vi-tamin D relative correction factor method to calculate the total amount of vitamin D simplified the experimental steps can be simplified by the pre-vitamin D relative correction factor method to calculate the total amount of vitamin D and the random operating errors can be avoided.The method is rapid and accurate,and lay a solid foundation for further improving the standard of vitamin D preparations.