In situ generation of high Aum clusters ions for mass calibration
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| Year of publication | 2016 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Gold clusters can be generated by Laser Desorption Ionization (LDI) of various gold nanomaterials e.g. gold nano-particles (AuNPs) of various geometry, or gold foil. In our study, Aum clusters generated from flower-like AuNPs were used for internal calibration of peptides1. A simple and effective method for in situ generation of high and stable gold cluster ions (Aum+ and Aum-) were developed. Then, the application of these clusters in external/internal calibration of mass spectra in both positive and negative ion modes was evaluated. The high efficiency of generation of clusters from AuNPs up to m/z 50002-3 has also been demonstrated although these high-mass gold clusters can be easily decomposed to low-mass clusters or even they can explode. Therefore, we aimed 1) to stabilize AuNPs by optimizing the matrices and the use of additives, 2) to extend the mass range towards high masses and 3) to obtain peaks with sufficient intensity and resolution to be usable for internal/external calibration of TOF or Q-TOF mass spectrometers. Among the different additives examined, citric acid/ammonium citrate buffer stabilizes AuNPs in aqueous solution and allows a reproducible generation of high-mass Aum clusters presenting high peak intensities and good resolution. We developed a simple and fast LDI method for the generation of gold clusters. These clusters present peaks, across the whole mass range up to m/z 17 000 in positive and up to m/z 6 000 in negative ion mode, with sufficient signal to noise ratios without using interfering matrices. Our results demonstrated that gold cluster ions can be used in precise in situ calibration in both low and high mass range. This calibration that can be carried out over high mass range without the use of interfering matrices is particularly suitable for MS of peptides and small proteins as well as for low molecular compounds such as metabolites, resulting in the development of more rapid and precise MS methods in biomedical research and diagnostics. |