Many compounds are challenging to analyze because they are isomers (have the same m/z) and also sometimes have the same HPLC retention time. And to make it even more complicated, sometimes there are two chiral forms that have different functions in biology, making it...
Cyclosporin A (CsA) has been a very successful immunosuppressant for preventing organ transplant rejection. It is a large cyclic peptide (11 residues, ~1200 Da) and there are numerous modifications of this drug, some of which are isomers. The challenge of analyzing...