SEC MW standards/markers, ~5 kDa, preferably peptides

[Millahh]

Does anyone know of some good, reasonably priced peptides in this mass range that I could use as a MW marker and in some recovery experiments in a validation? The methods is for determination of multimers of a 2.5 kDa peptide, so i'm looking for something ~5 kDa, and maybe something 7-8 kDa as well. No commercial SEC std kit i've found has anything as low as what I'm looking for, and looking up the MW of every known peptide, then pricing them seems a bit...inefficient.

[Vlad Orlovsky]

Insulin can work for you. It is 5808....and you can get it even from drug store

[Millahh]

Thanks!

Come to think of it, I need something around 3 kDa, as well (unfortunately, the B-chain of insulin is a bit pricey).

[Vlad Orlovsky]

You can get insulin for Walgreens or other drug store for about $80 bottle. Bottle has 10 ml solution of insulin (about 3.5 mg/ml) plus other stuff (glycerol, polysorbate, etc.). You might have somebody with diabetes around who can donate you few ml.

[Millahh]

Sigma had a good price...100 mg bovine insulin for $120, so i bought a few bottles.