High-Reactivity Matrices Increase the Sensitivity of Matrix Enhanced Secondary Ion Mass Spectrometry

• Published in: Analytical chemistry (Washington) Vol. 83; no. 21; pp. 8308 - 8313
• Main Authors: Svara, Fabian N, Kiss, Andras, Jaskolla, Thorsten W, Karas, Michael, Heeren, Ron M. A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.2011
• Subjects: Analytical chemistry; Chemistry; Coumaric Acids - chemistry; Desorption; Exact sciences and technology; Gentisates; Mass spectrometry; Peptide Fragments - chemistry; Peptides; Sensitivity and Specificity; Spectrometric and optical methods; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrometry, Mass, Secondary Ion; Performance evaluation; Choice; Peptides; Ion beam; Secondary ion; Standard; Matrix assisted laser desorption ionization; Laser desorption; Mixture; Fragmentation; Improvement; Signal; Absorption; Proton affinity; Sample; Use; Secondary ion mass spectrometry; Absorption coefficient; Method; Wavelength; Sensitivity; Ionization; Laser; Yield; Gas phase; Mass spectrometry; Physicochemical properties
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac202222h

Secondary ion mass spectrometry (SIMS) is a desorption/ionization method in which ions are generated by the impact of a primary ion beam on a sample. Classic matrix assisted laser desorption and ionization (MALDI) matrices can be used to increase secondary ion yields and decrease fragmentation in a SIMS experiment, which is referred to as matrix enhanced SIMS (ME-SIMS). Contrary to MALDI, the choice of matrices for ME-SIMS is not constrained by their photon absorption characteristics. This implies that matrix compounds that exhibit an insufficient photon absorption coefficient have the potential of working well with ME-SIMS. Here, we evaluate a set of novel derivatives of the classical MALDI matrices α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB) for usability in ME-SIMS. This evaluation was carried out using peptide mixtures of different complexity and demonstrates significant improvements in signal intensity for several compounds with insufficient UV absorption at the standard MALDI laser wavelengths. Our study confirms that the gas-phase proton affinity of a matrix compound is a key physicochemical characteristic that determines its performance in a ME-SIMS experiment. As a result, these novel matrices improve the performance of matrix enhanced secondary ion mass spectrometry experiments on complex peptide mixtures.