traction Buffer - 1L Final Concentrations SDS/NaCl Extraction Buffer - 1L

100ml 1.0M Tris-HCl pH 7.5 0.1M Tris-HCl pH 7.5 200ml 1M Tris-HCl pH 7.5 = 0.2M (200mM)

100ml 0.5M EDTA pH 8.0 0.05M EDTA pH 8.0 50ml 0.5 EDTA pH 8.0 = 0.025M (25mM)

125ml 10% SDS 1.25% SDS 50ml 10% SDS = 0.5%

675ml ddH2O 50ml 5M NaCl = 0.25M (250mM)

*add 200μl 10mg/ml RNase 0.002mg/ml RNase 650ml ddH2O

after heating to 65°C

I know this is years too late, but you can very often get an approximate idea about the buffer composition from the material safety data sheet (MSDS). For buffer AL, it says guanidine hydrochloride 30-50%. Then there is also some maleic acid, which is probably part of the buffer they use. When we recently isolated genomic DNA from animal tissue and we ran out of buffer AL (or rather: nobody could find it after we had moved into new lab space), we replaced buffer AL with an unbuffered 40% guanidine hydrochloride solution and the isolation went fine.

Here the link to the MSDS: https://sds.qiagen.com/ehswww/QIAGENwww/result/report.jsp?P_LANGU=E&P_SYS=4&P_SSN=20051&P_REP=00000000000000000121&P_RES=37212

Concerning the notion that "you are not supposed to know the composition of buffers supplied by manufacturers along with their kits", I think this is a very dangerous idea. If things do not work as expected, it is very difficult to troubleshoot if you have no idea about the underlying chemistry that you are using. Let alone about reproducibility if the kit vendor goes out of business. Reproducibility is one of the corner stones of science and you give up a great deal of that if you rely on "black boxes" like proprietary kits. Imho all kits should be fully documented and the added value of a kit should be only in its convienience, but not in its "secret components". BTW there is a student protocol available from Vanderbilt, where the individual components of the Qiagen genomic DNA isolation kit and their functions are explained: https://cdn.vanderbilt.edu/vu-wp0/wp-content/uploads/sites/267/2019/06/19164057/Lab2_DNA_19June2019.pdf