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Sample pretreatment on a microchip with an integrated electrospray emitter
Author(s) -
Lindberg Peter,
Dahlin Andreas P.,
Bergström Sara K.,
Thorslund Sara,
Andrén Per E.,
Nikolajeff Fredrik,
Bergquist Jonas
Publication year - 2006
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500763
Subject(s) - electrospray , wafer , chromatography , coating , microbead (research) , materials science , common emitter , graphite , chemistry , analytical chemistry (journal) , nanotechnology , mass spectrometry , composite material , optoelectronics , biochemistry
This study presents a microbead‐packed PDMS microchip with an integrated electrospray emitter for sample pretreatment prior to sheathless ESI‐MS. We prove the concept of analytical functions integrated onto a cm‐sized area of a single bulk material. The microchip consists of two PDMS substrates replicated from SU‐8 fabricated silicon wafer masters, bonded together after oxidation by corona discharge treatment. The channel within the microchip contains a grid structure that was used to trap 5 µm hypercross‐linked polystyrene beads. The beads acted as a medium for sample desalting and enrichment. Electrical contact for the sheathless ESI process was achieved by coating the integrated emitter with conductive graphite powder after applying a thin layer of PDMS as glue. The coating as well as the bond of the PDMS structures showed excellent durability. A continuous spray was obtained from the microchip for over 800 h in a long‐term electrospray stability experiment. Desalting and enrichment of neuropeptides from a physiological salt solution was successful by loading the sample onto the packed beads, followed by a washing and an eluting step. The results were obtained and evaluated using a TOF MS. An LOD of approximately 20 fmol (loaded onto the beads) for angiotensin II was obtained from a sample of neuropeptides dissolved in physiological salt solution.