CE and hydrogen-deuterium (H/D) exchange MS are useful tools in the analysis and characterisation of peptides. This study reports the facile coupling of these tools in the H/D exchange CE-MS analysis of model and pharmaceutically important peptides, using a sheath flow interface. The peptides varied in mass from 556 (leucine enkephalin) to 1620 Da (bombesin), and in charge state from 0.33 (leucine enkephalin) to 3.0 (substance P). The application of a BGE composed of ammonium formate buffer (25 mM, pD 3.5 in D2O (>98% D atom)), a sheath liquid composed of formic acid (0.25% v/v in D2O) and ACN (30:70 v/v), and dissolving the samples in a mixture of ACN/D2O (50:50 v/v) facilitates complete H/D exchange. Because of complete H/D exchange the ESI mass spectra produced are easy to interpret and comparable to those obtained from LC-MS analysis. The CE-H/D-MS approach has the advantage of requiring lower volumes of deuterated solvents. The b- and y-series fragments produced by using in-source decomposition correspond to those predicted. With the peptides studied, the complete exchange H/D exchange observed with both the molecular and fragment ions helps to confirm both amino acid composition and sequence.
- hydrogen-deuterium exchange