RP-HPLC solvent B with 0.09% TFA
Trifluoroacetic acid, neat (TFA)
Add 600 ml of acetonitrile to a 1-liter glass-stoppered cylinder. Add 400 ml H2O to a second 1-liter cylinder, then combine the two. Add 0.9 ml of neat trifluoroacetic acid (TFA) and mix the solution thoroughly.
Use HPLC-grade acetonitrile, TFA, and H2O. Final concentrations are 60% acetonitrile/40% H2O (v/v) containing 0.09% (v/v) trifluoroacetic acid.
(The volumes of organic solvent and H2O must be measured in two different cylinders and then combined because of volume contraction upon mixing, which may be up to 30 ml/liter prepared solvent. Failure to do so can lead to substantial errors in mobile-phase composition.)
