Using sol–gel/crown ether hybrid materials as desalting substrates for matrix‐assisted laser desorption/ionization analysis of oligonucleotides

Abstract

This study demonstrates the feasibility of using sol-gel/crown ether hybrid materials as sample substrates that reduce the intensity of the signals of sodium ion adducts of oligonucleotides during matrix-assisted laser desorption/ionization (MALDI) analysis. 2-Hydroxymethyl[15]crown-5 and 2-hydroxymethyl[18]crown-6 were added as dopants during the sol-gel process to generate desalting substrates for MALDI sample deposition. The results demonstrate that the sol-gel/crown ether hybrid materials effectively suppress the formation of sodiated oligonucleotides during MALDI analysis. The largest detectable molecular size for an oligonucleotide was a 100-mer, and the detection limit for an oligonucleotide 36-mer was ca. 20 fmol.

Selective or Class-wide Mass Fingerprinting of Phosphatidylcholines and Cerebrosides from Lipid Mixtures by MALDI Mass Spectrometry

“…For example, sol-gel/ crown ether hybrid material was used to reduce the sodium adduct ion signals of oligonucleotides. 8 Lastly, lipid analysis in the negative ion mode could reduce the spectral complexity since most species were detected in the form of…”

Using solvent‐free sample preparation to promote protonation of poly(ethylene oxide)s with labile end‐groups in matrix‐assisted laser desorption/ionisation

“…Different procedures have been reported to reduce or eliminate salt contaminants in samples, solvents or on the target plate. Amongst them, recrystallization of the matrix, washing the MALDI plate, direct desalting on the probe tip or use of dopants (crown ether, cation exchange resin beads) aimed at trapping residual cations in sample have been proposed 29–32…”

Adduct simplification in the analysis of cyanobacterial toxins by matrix‐assisted laser desorption/ionization mass spectrometry

“…The use of the cyclic polyether 18‐crown‐6 to complex sodium and potassium ions in solution has been shown to dramatically reduce cation adducts during the analysis of trypsin digests31 and intact bacterial cells 32, 33. Crown ethers have also been incorporated into a sol‐gel material to generate a desalting substrate for MALDI sample deposition 34. Other conditions tested for suppression of cation adducts include addition of surfactants26, 28 and ammonium salts29, 35, 36 to the matrix, and the use of ionic liquids in place of solid matrices 37, 38…”

“…32,33 Crown ethers have also been incorporated into a sol-gel material to generate a desalting substrate for MALDI sample deposition. 34 Other conditions tested for suppression of cation adducts include addition of surfactants 26,28 and ammonium salts 29,35,36 to the matrix, and the use of ionic liquids in place of solid matrices. 37,38 Some researchers have taken the opposite approach and attempted to force the formation of particular cation adducts through the addition of metal salts.…”