Advantages of pressurization in capillary electrophoresis/electrospray ionization mass spectrometry

In this paper we present a simple interface for coupling capillary electrop horesis (CE) to mass spectrometry (MS) which can operate without significan t user intervention. The use of a dedicated interface allows rapid changeov er between CE/MS and liquid chromatography (LC)/MS, which is particularly i mportant as CE and LC are often used on the same mass spectrometer, The sui tability of the interface construction is illustrated on a triple quadrupol e mass spectrometer and a high-resolution time-of-flight mass spectrometer with compounds such as peptides, vitamins, and carbohydrates. Separations o f these compounds are also used to evaluate the robustness of the CE-MS int erface under pressurized and nonpressurized modes of operation. The simulta neous application of pressure and voltage overcomes two of the major proble ms commonly encountered when coupling CE to MS, i.e. unreliable long-term o peration and protracted analysis times due to the long separation capillari es needed to connect to the mass spectrometer, Concomitant application of h igh voltage and hydrostatic pressure significantly reduces analysis time wi thout compromising the overall separation. It was observed that pressurized CE exhibits less run-to-nm-variations, leading to run-to-run repeatability better than 0.5% for migration time and below 5% for peak area with the MS as detector.