Preconcentration and separation of all proteinogenic amino acids by hyphenation of isotachophoresis and capillary electrophoresis mass spectrometry.

MELTZER, T.; HUHN, CAROLIN; RATH, P.; KLER, PABLO A.

Cork

Simposio; 31st International Symposium on Chromatography (ISC2016).; 2016

Isotachophoresis (ITP) is an electromigrative separation technique which is often applied for preconcentration of analytes and removal of sample matrix. Its application is generally restricted to analytes of high to intermediate effective electrophoretic mobility and thus often not applicable for weak acids and bases as the mobility window is impaired by H+ or OH- at very low or high pH values required to sufficiently charge the analytes. Thus, the preconcentration of all proteinogenic amino acids is impossible in aqueous ITP as some analytes are excluded from the isotachophoretic stack and migrate zone-electrophoretically in the terminating electrolyte.To enable an ITP preconcentration of all proteinogenic amino acids as cations, a non-aqueous electrolyte system using the aprotic solvent dimethylsulfoxide (DMSO) was developed by Kler et al.[1]. Mass spectrometry (MS) and capacitively coupled contactless conductivity detection (C4D) were applied to monitor the ITP processes. By ITP-MS, different capillary inner diameters and changes in the electrolyte system were examined. In this study, we use this ITP system as the first dimension in ITP/CE-MS implemented in a modular setup for on-linecolumn-coupling of ITP and CE-MS using a microfluidic glass interface with intermediate C4D detection. We here show the possibilities and limitations for the effective ITP preconcentration of proteinogenic amino acids before CE-MS analysis varying injection parameters, capillary inner diameters and lengths in the first dimension. Matrix effects and matrixremoval is investigated using high salt conditions.