Application of DNA-binding polymers for preparation of DNA for analysis bymatrix-assisted laser desorption/ionization mass spectrometry

The susceptibility of matrix-assisted laser desorption/ionization mass spec trometry (MALDI-MS) to the presence of salts in a sample, especially salts of alkali metals, requires careful and often tedious desalting procedures w hich complicate and slow the throughput of MS-based methods. A novel approa ch to sample preparation was developed based on the extraction of DNA out o f solution onto a solid surface with an attached DNA-binding polymer, such as polyethyleneimine or polyvinylpyrrolidone. The observed binding is stron g enough to sustain washing, and, as a result, desalting and concentration can be performed in a single fast step. After DNA has been immobilized on t he surface and supernatant solution removed, subsequent addition of MALDI m atrix releases material from the surface, which co-crystallizes with matrix . The mass spectrometric analysis is then performed directly from this supp ort. Analysis of oligonucleotides and three-fold multiplexed SNP typing rea ctions performed by this method shows improved sensitivity and excellent re solution for various DNA fragments, together with high tolerance to various buffer components, such as alkali metals and surfactants. Simplicity and s peed make it attractive for high-throughput sample preparation and analysis of oligonucleotide mixtures by MALDI-MS. Copyright (C) 2001 John Wiley & S ons, Ltd.