Sheathless electrospray from polymer microchips.
In this study, sheathless electrospray from polymer microchips with conducting layer on the emitter tip is described for the first time. The electrospray emitter tips were fabricated directly from the end of the microchips that were made of polycarbonate or poly(methyl methacrylate) with injection molding. A variety of tip shapes and conducting coatings were evaluated using an electrospray time-of-flight mass spectrometer run in the sheathless mode. Stable electrospray was obtained both from hand-polished and machine-milled three-dimensional tips coated with either polymer-embedded gold particles or graphite particles as the conducting layer. Sputtered gold, on the other hand, suffered from poor stability mainly due to bad adhesion to the polymer tip. The durability of the different coatings was confirmed with electrochemical experiments under simulated electrospray conditions. The relative standard deviations of the response received from the ion current of the MS analysis were in the range of 3.5-12%. The detection limit for a standard mixture containing five neuropeptides was lower than 0.5 fmol. The low detection limit makes the emitter tips highly attractive for the analysis of low-abundance biological species.
The Angstrom Laboratory, Department of Materials Science, Uppsala University, PO Box 534, 751 21 Uppsala, Sweden.
Malin
M
Svedberg
Andreas
A
Pettersson
Stefan
S
Nilsson
Jonas
J
Bergquist
Leif
L
Nyholm
Fredrik
F
Nikolajeff
Karin
K
Markides
D004563:Electrochemistry; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry; D009479:Neuropeptides / Q000032:analysis; D011076:Polycarboxylate Cement; D011108:Polymers; D019904:Polymethyl Methacrylate; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation* / Q000379:methods*
D009479:Neuropeptides; D011076:Polycarboxylate Cement; D011108:Polymers; C005506:polycarbonate; D006046:Gold; D006108:Graphite; D019904:Polymethyl Methacrylate