High-resolution droplet-based fractionation of nano-LC separations onto microarrays for MALDI-MS analysis.
We present a robust droplet-based device, which enables the fractionation of ultralow flow rate nanoflow liquid chromatography (nano-LC) eluate streams at high frequencies and high peak resolution. This is achieved by directly interfacing the separation column to a micro T-junction, where the eluate stream is compartmentalized into picoliter droplets. This immediate compartmentalization prevents peak dispersion during eluate transport and conserves the chromatographic performance. Subsequently, nanoliter eluate fractions are collected at a rate of one fraction per second on a high-density microarray to retain the separation with high temporal resolution. Chromatographic separations of up to 45 min runtime can thus be archived on a single microarray possessing 2700 sample spots. The performance of this device is demonstrated by fractionating the separation of a tryptic digest of a known protein mixture onto the microarray chip and subsequently analyzing the sample archive using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Resulting peak widths are found to be significantly reduced compared to standard continuous flow spotting technologies as well as in comparison to a conventional nano-LC-electrospray ionization-mass spectrometry interface. Moreover, we demonstrate the advantage of our high-definition nanofractionation device by applying two different MALDI matrices to all collected fractions in an alternating fashion. Since the information that is obtained from a MALDI-MS measurement depends on the choice of MALDI matrix, we can extract complementary information from neighboring spots containing almost identical composition but different matrices.
Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland.
Simon K
SK
Küster
Martin
M
Pabst
Konstantins
K
Jefimovs
Renato
R
Zenobi
Petra S
PS
Dittrich
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D046228:Microarray Analysis / Q000295:instrumentation*; D036103:Nanotechnology; D011492:Protein Hydrolysates / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D011492:Protein Hydrolysates