Preparation of 200 mM amino acid monomer:DMSO:HCl solution
Into 92.5 μL of dimethyl sulfoxide (DMSO) and 7.5 μL of 25% HCl, 3.3 mg of amino acid monomer (Phe, Tyr, Trp,Ile ,or Val) are added and vortexed for 5 minutes until total dissolution is observed.