sorry for late, Thank you for the notification of such problems
the quality control department will know as well as in the standard treatment products the best forever.
1. From the inspection standard 0.05m EDTA there may be products with production since the month 9 / 2014 (lot no.490472) At the last time of 6 months. But we do have not infromation this from customer, and this product can only produce 5 bottle.
2. I have sent by attached documents were all produced 5 bottle only this lot.
3. We will attach a document to method Standardization and Validation sample 0.05M EDTA
4. I suggest the compare chemical 0.05 M EDTA ,it should be done compared with the 0.05M EDTA only (the same concentration)
For the preparation of standard compounds with other examples that. We continue to follow international standards are given.
preparations of standard used in titrated every sample.