Separation and measurement of desmosine and isodesmosine in vascular tissue hydrolysates by micellar electrokinetic capillary chromatography with a mixed micelle system

A micellar electrokinetic capillary chromatography (MEKC) method with a mixed micelle system for separation and measurement of desmosine (DES) and isodesmosine (IDES) in vascular tissue hydrolysates is described. The mixed micelle system was composed of a zwitterionic surfactant named 3-(N,N-dimethylhexadecylammonium)propanesulfonate (PAPS) and a nonionic surfactant polyethylene glycol dodecyl ether (Brij 35). By using 50 mM Tris–H3PO4 (pH 2.5) containing 40 mM PAPS and 0.5% (m/v) Brij-35 as the optimal running buffer, DES and IDES were baseline separated from each other and from other hydrolyzed components of the vascular tissue. The limit of quantitation (LOQ) for DES and IDES were 3.00 × 10−6 mol/L and 2.75 × 10−6 mol/L, respectively. The relative standard deviation (RSD) of migration times and corrected peak area in terms of the inter-day and the intra-day repeatability were less than 1.7%. Hydrolysate samples of vascular tissues of rats were analyzed with the MEKC method with satisfied results.