Alkylated Hydroxychalcone: A Novel Matrix for Peptide Analysis by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry.

In matrix-assisted laser desorption ionization mass spectrometry, a suitable matrix is often selected for the analyte. Herein, we first developed a novel matrix, alkylated hydroxychalcone (AHC), which has properties similar to alkylated trihydroxyacetophenone (ATHAP) (Anal. Chem., 85: 9444-9448, 2013) developed as a matrix for hydrophobic peptides. However, the sample-to-sample reproducibility was low because of the poor crystallinity of AHC. The crystalline morphology of AHC changed when AHC/2,5-dihydroxybenzoic acid (DHB) was used as a binary matrix. As a result, the use of AHC/DHB improved sample-to-sample reproducibility and increased sensitivity for hydrophobic peptides. Mass imaging indicated that these results were due to an increased number of sweet spots wherein the analytes were detected as ion peaks, in a matrix/analyte crystal spot.