p-nitroaniline/glycerol: a binary liquid matrix for matrix-assisted laser desorption/ionization analysis

Liquid matrices for matrix-assisted laser desorption/ionization (MALDI) ana lysis offer advantages over solid matrices including increased shot-to-shot reproducibility and the ability to provide conditions more suitable for th e retention of non-covalent complexes, Unfortunately, most of the liquid ma trices available do not absorb at UV wavelengths. A second component to inc rease chromophoric absorption and to permit control over the chemical prope rties of the matrix can aid in overcoming some of the limitations currently faced by the MALDI technique. In the work reported here, a binary matrix t hat combines the advantages of the fluidity and low vapor pressure of glyce rol with the weak basicity and chromophoric properties of p-nitroaniline is evaluated. Both positive-ion and negative-ion spectra are obtained for pro teins, carbohydrates and oligonucleotides, The potential for analysis of ch elates and noncovalent interactions using this liquid binary matrix is also explored.