VALIDATION OF THE COULOMETRIC METHOD FOR WATER DETERMINATION IN THE SUBSTANCE OF ROSUVASTATIN
One of the mandatory controlled parameters of pharmaceutical substances is «water». Water content can change with improper storage and lead to the occurrence of such undesirable processes as hydrolysis, oxidation of the drug and the appearance of toxic impurities.The purpose of this study is development and validation of coulometric method for determination of the water content in thesubstance of rosuvastatin by the Fisher method. Material and methods: The object of the study was the pharmaceutical substance rosuvastatin (Amoli Organics Pvt. Ltd., India). The measurements were carried out on the coulometer «Expert-007» («Econix-Expert», Russia) using modified Fisher's reagents: KFI-Anode and KFI-Cathode («Aquametria», Russia). The leakage test of the coulometric cell was carried out by measuring the drift, which did not exceed 0.05 mg H2O/min. The accuracy of the water determination was checked using a standard solution HYDRANAL - Check Solution 1.00 with a content of 1.00 mg H2O/g.Results: The method was validated in terms of the following indicators: specificity, linearity (r = 0.9991) and application range,accuracy and precision (relative standard deviation ( S r) does not exceed 0.02).Conclusion: The validation assessment showed the validity of the coulometric determination of the water content in the sub-stance of rosuvastatin according to the Fisher method.