| Abstract
| - An array of emitters has been developed for increasingthe sensitivity of electrospray ionization mass spectrometry (ESI-MS). The linear array consists of 19 chemicallyetched fused-silica capillaries arranged with 500 μm(center-to-center) spacing. The multiemitter device has alow dead volume to facilitate coupling to capillary liquidchromatography (LC) separations. The high aspect ratioof the emitters enables operation at flow rates as low as20 nL/min/emitter, effectively extending the benefits ofnanoelectrospray to higher flow rate analyses. To accommodate the larger ion current produced by the emitterarray, a multicapillary inlet to the mass spectrometer wasalso constructed. The inlet, which matched the dimensions of the emitter array, preserved ion transmissionefficiency. Standard reserpine solutions of varying concentration were electrosprayed at 1 μL/min using themultiemitter/multi-inlet combination, and the results werecompared to those from a standard, single-emitter configuration. A 9-fold sensitivity enhancement was observedfor the multiemitter relative to the single emitter. A bovineserum albumin tryptic digest was also analyzed, and asensitivity increase ranging from 2.4- to 12.3-fold for thedetected tryptic peptides resulted; the varying responsewas attributed to reduced ion suppression under thenanoESI conditions afforded by the emitter array. Anequimolar mixture of leucine enkephalin and maltopentaose was studied to verify that ion suppression is indeedreduced for the multiplexed ESI (multi-ESI) array relativeto a single emitter over a range of flow rates.
|
