Detection of 7-N,N-dimethylaminosulfonyl-4-(2,1,3-benzoxadiazolyl) carbamoyl amino acids generated by post-column desulfuration in the simultaneous determination of the sequence and d/l-configuration of peptides using a fluorogenic Edman reagent, 7-N,N-dimethylaminosulfonyl-4-(2,1,3-benzoxadiazolyl)