Determination of related substances in telmisartan by HPLC
Objective:To establish an HPLC method for the determination of the related substances in telmisartan.Methods:Waters Symmetry Shield RP8(150 mm x4.6 mm,3.5 µm)column was adopted.The mobile phase A was 0.1%phosphoric acid solution(pH was adjusted to 3.0 with triethylamine),and the mobile phase B was acetonitrile.The gradient elution was performed.The flow rate,column temperature and wavelength were 0.8 mL·min-1,25 ℃ and 230 nm,respectively.Results:The resolutions between the peaks of telmisartan and nine known impurities were greater than 1.5.The limits of quantitation of all impurities were less than 40 ng·mL-1,and the limits of detection of all impurities were less than 10 ng·mL-1.The standard curves of telmisartan and its impurities were linear within the range 30-600 ng·mL-1,and the correlation coefficients were all greater than 0.999 5.The average recovery rates of impurities Ⅰ-Ⅸ were 93.8%,99.8%,97.5%,99.2%,99.8%,98.3%,98.4%,99.2%and 99.7%,respectively,and the RSDs of 9 results were all less than 2.0%.Changing the flow rate,column temperature,wavelength,mobile phase ratio and pH did not affect the detection results of the related substances.The results of maximum single impurity were 0.02%in three batches of telmisartan,and the results of total impurities were less than 0.10%.Conclusion:The method is highly specific,sensitive,precise and accurate,and can be used for the determination of related substances of telmisartan.