Product A2661 is tested for the suitability of cell culture applications. Please see the product specification sheet to view the testing done on this product:
https://www.sigmaaldrich.com/specification-sheet/SIGMA/A2661
Product A6625 is not tested for the suitability of cell culture applications. Please see the specification sheet to view the testing done on this product:
https://www.sigmaaldrich.com/specification-sheet/SIGMA/A6625