Optical Detection and Charge-State Analysis of MALDI-Generated Particles with Molecular Masses Larger Than 5 MDa

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• 作者：Y. Cai ; W.-P. Peng ; S.-J. Kuo ; S. Sabu ; C.-C. Han ; and H.-C. Chang
• 刊名：Analytical Chemistry
• 出版年：2002
• 出版时间：September 1, 2002
• 年：2002
• 卷：74
• 期：17
• 页码：4434 - 4440
• 全文大小：176K
• 年卷期：v.74,no.17(September 1, 2002)
• ISSN：1520-6882

文摘

Charged polystyrene nanoparticles are generated by matrix-assisted laser desorption/ionization (MALDI) and detected by laser-induced fluorescence (LIF) in a quadrupole ion trap. Employing the LIF technique, observationsof individual fluorescent nanospheres (27 nm in diameterand containing 180 fluorescein dye equivalents) havebeen achieved with an average signal-to-noise ratio of~10. With the trap operating at a frequency around 5 kHz,charge state analysis of the particles reveals that thenumber of charges carried by the spheres is between 1and 10. It suggests a mass-to-charge ratio (m/z) in therange of 10⁵-10⁶ for the MALDI-generated particles. Toeffectively trap such large particles (m > 5 MDa), dampingof the particles' motions by using ~50 mTorr He buffergas is absolutely required. Similar findings are obtainedfor particles with a nominal size of 1 m in diameter,demonstrating that production of charged particles witha molecular mass as high as 10¹² Da is possible usingthe MALDI technique.