These products are very comparable in terms of quality. All offer a minimum purity specification of 99%. They have the same CAS number and molecular weight. The differences are primarily in the testing and demonstrated suitability. Product 8.00830 is simply tested for purity, melting point, and identity by IR. Product A3553 and product A9909 are tested for free carboxylate, purity, heavy metals (including Fe and Mg) solubility, and conductivity. In addition, product A9909 is also tested for RNAse, DNAse, Protease, and Exonuclease. Finally, product A3553 is tested for suitability in electrophoresis.
Please see the link below to compare the features and benefits of each item:
https://www.sigmaaldrich.com/product/compare?term=800830&focus=products&page=1&perpage=30&sort=relevance&type=product&products=800830%3AMM%3Asial%2CA9099%3ASIGMA%3Asial%2CA3553%3ASIGMA%3Asial
Product 146072 and M7279 are similar. Product 146072 is a research grade suitable for gel preparation. Product M7279 was tested for molecular biology. There is more testing done for item M7279. Please view the sample Certificate of Analysis for each item:
https://www.sigmaaldrich.com/certificates/sapfs/PROD/sap/certificate_pdfs/COFA/Q14/146072-BULKMKCT3390.pdf
https://www.sigmaaldrich.com/certificates/sapfs/PROD/sap/certificate_pdfs/COFA/Q14/M7279-250G0000238507.pdf