Hello,

We have synthesized the cyclic peptide (D-Glu(OtBu)-L-Lys(Alloc)-D-Glu(OtBu)-L-Ala)2.

LC-MS shows a mixture of linear and cyclic peptides.

There is only one peak by HPLC (reverse phase, H2O + 0.1% TFA & CH3CN + 0.08% TFA) and modification of the %eluants did not allow to see 2 peaks.

After cleavage of the tBu groups, we can still not distinguish 2 peaks by HPLC.

Any advice to separate the cyclic peptide from the linear peptide is welcome!

Thanks a lot.