Picolinic acid as a matrix for laser mass spectrometry of nucleic acids and proteins

We found that picolinic acid is a very good matrix for matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry of Oligonucleotides, proteins and tRNA. Among the Oligonucleotides, picolinic acid was shown to be effective for homo-oligonucleotides, d(G)40 and d(C)60, and for mixed-base Oligonucleotides up to 190 Bases. In the case of the single-stranded Oligonucleotides, and of double-stranded ones as well, only parent ions corresponding to single-stranded DNA were observed. The efficiency for MALDI of Oligonucleotides using the picolinic acid matrix was superior to that using 3-hydroxypicolinic acid. MALDI of transfer RNA phenylalanine-specific (tRNA(Phe)), a 76-base ribonucleic acid, was detected with a signal-to-noise ratio of > 10. By comparison with 3-hydroxypicolinic acid the results with picolinic acid are notably superior for all Oligonucleotides.