title: Liquid chromatography-matrix-assisted laser desorption/ionization mass spectrometric imaging with sprayed matrix for improved sensitivity, reproducibility and quantitation.
abstract: Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging (MSI) has been employed as a detection method for both capillary electrophoresis (CE)-MALDI and liquid chromatography (LC)-MALDI analyses. Based on our previous studies, here we report a new interface to couple LC with MSI by employing an automated matrix sprayer. The LC trace is directly collected on a ground stainless steel MALDI plate and dried. The matrix is sprayed on the MALDI plate using a programmable matrix sprayer. With the highly uniform matrix layers produced from the sprayer, the MS image signal quality is significantly improved with enhanced signal-to-noise ratios for analyte peaks. With the programmable matrix application and imaging MS data acquisition, the new LC-MSI platform exhibits highly stable and reproducible performance. A total of 87 bovine serum albumin (BSA) tryptic peptides and 295 putative neuropeptides from blue crab pericardial organs have been observed with LC-MSI analysis, exhibiting better performance in terms of peptide coverage than regular LC-MALDI with discrete spot collection and our previously reported LC-MSI interface with the matrix being delivered by a capillary. In addition to relative quantitation with isotopic labeling as we have previously demonstrated, we performed the first absolute quantitation using the new LC-MSI platform and obtained accurate quantitation results for neuropeptides, indicating great potential for quantitative analysis of complex samples.
authors.affiliation: School of Pharmacy, University of Wisconsin, 777 Highland Avenue, Madison, Wisconsin 53705, USA. lli@pharmacy.wisc.edu.
authors.forename: Zichuan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Kuang
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D003386:Brachyura; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods* / Q000592:standards*
chemical_list: D012710:Serum Albumin, Bovine