Adjusting the laser wavelength to the optical absorption of novel halogen-substituted MALDI matrices for enhanced MS performance

摘要

Six different halogenated CHCA derivatives with sizably different proton and cation affinities were investigated. Matrices with low proton/cation efficiency can enhance the analytical sensitivity for the MALDI analysis of both peptides and oligosaccharides. Due to the hypsochromic shift in absorption, making full use of the potential of the novel matrices requires adjustment of laser wavelength. Even for standard CHCA matrix an enhanced performance is obtained by adjusting the wavelength. To first order, an inverse relation between threshold energy (to generate a mass spectrum) and the optical absorption of matrix is observed. Minimal sample consumption is observed at peak optical absorption of the matrix. Higher photon energies on the "blue" shoulder of the absorption band increase fragmentation of matrix ions and yield lower pe ptide ion signals. PentaFCCA matrix, employed at 280 nm, produces particular high abundances of cationized oligosaccharides, similarly to standard DHB matrix.