An Integrated Approach to Desalting and Concentrating Peptide/Protein Samples for MALDI MS Analysis

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Weibin Chen, Peter J. Lee, Edouard S. P. Bouvier, Jeffrey W. Finch, John C. Gebler[Waters] Jeff Brown, Emmanuelle Claude, Dominic Gostick, James Langridge[Micromass]
ASMS 2002; Orlando; 4 June 2002
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Peptide, Protein, Ovalbumin, Desalting
Matrix-assisted laser desorption and ionization mass spectrometry (MALDI-MS) is a powerful tool for protein identifications. This has been mainly due to its ease of use and relatively insensitivity to biological matrixes resulting from sample preparations. However, it has been demonstrated that the success rate of protein identification can be greatly enhanced by improving the sensitivity of analysis and by removing the contaminants contained in the biological samples. Traditionally, a micro-column packed with reverse-phase materials such as ZipTipTM is often used as a final desalting and concentrating step prior to MALDI analysis.1 Because micro-columns can process sample as little as submicro-liters, this processing method is well suited to proteomics research where available sample volume for analysis is often very limited. However, as an additional step in sample preparation, desalting of the samples is often time consuming and will lead to sample loss. We developed an innovative sample preparation technology for MALDI analysis of biological samples. It integrates both sample desalting and sample concentrating functions into a MALDI plate, and therefore allows sample preparation directly on the plate, thus considerably simplifying sample preparation process. Samples containing commonly used salts or detergents were evaluated, and results are compared with alternative MALDI sample preparation method. Furthermore, it is demonstrated that analysis of peptide mixtures (artificial mixture and protein digests) performed by the plate shows excellent sensitivity – with at least one order magnitude improvement over standard stainless steel plates.

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