Official method used in the analysis are not required to perform validation of the test method (Method Validation), but use and suitability of the methods should be checked against the actual environment.
If using the official method of analysis. No need to check the accuracy of the test method (Method Validation), but the available and appropriate method should be checked against the real environment.
In case of using official method in analysis. No verified test methods (Method Validation), but the available and appropriate how should check with the environment.