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Development of a novel sheathless CE-ESI-MS interface via a CO2 laser ablated opening
Journal Contribution - Journal Article
A new and easy to construct sheathless capillary electrophoresis electro spray ionization mass spectrometry (CEESI-MS) interface was developed that offers several advantages compared to traditional liquid junction interfaces. The fabrication of the device only requires a CO2 laser engraver that most groups working with microfluidshave access to. It only takes a few seconds to create a CO2 laser ablated opening in the bare-fused silica capillaries and the opening can be placed as close as a few mm from the spray tip. The capillary is puncturedthrough a silicone tube such that the opening is directly placed inside this tube, which also serves as a liquidreservoir for the make-up liquid. Electrical contact required for both CE separation and ESI is established via theliquid in this reservoir which is in contact with the electrode of an external high voltage power supply. Thedeveloped CE-ESI-MS interface is capable of analysing both small molecules and biomolecules such as peptidesin physisorbed PEG polymer brush coated capillaries. Proof-of-principle of the interface was demonstrated byanalysing a tryptic digest of BSA. Further, a range of drugs of abuse were also investigated. The examined smallmolecules (pethidine, nortriptyline, methadone, haloperidol and loperamide) have a quantification limit (LOQ)of 150 ng/mL and a detection limit (LOD) of 40 ng/mL (except for loperamide: LOD = 80 ng/mL). Finally, weused our novel CE-MS interface for the analysis of the Aβ40 peptide. This is a member of the beta-Amyloidpeptide family, involved in the development of Alzheimer's disease. A LOQ of 9 μg/mL was obtained for Aβ40,corresponding to 23 fmoles in a sample volume of 11 nL.
Number of pages: 8