Trimpin Sarah, Weidner Steffen M, Falkenhagen Jana, McEwen Charles N
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
Anal Chem. 2007 Oct 1;79(19):7565-70. doi: 10.1021/ac070986w. Epub 2007 Sep 7.
A solvent-free homogenization/transfer matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) method is described for the preparation and precise transfer of up to 100 samples simultaneously on a single MALDI plate. This method is demonstrated using a poly(ethylene oxide) (PEO) mixture consisting of different molecular weights (500-6000) and end groups (PEO, dimethoxy-PEO, monomethoxy monomethacrylate-PEO, and dimethacrylate-PEO) that was fractionated using liquid adsorption chromatography at critical conditions. Off-line fractionation is performed prior to the on-target homogenization/transfer solvent-free sample preparation and MALDI mass analysis. The miniaturization of the solvent-free MALDI approach allowed analysis of less than 2 microg per PEO component per fraction corresponding to approximately 200 pmol for PEO 6000. The amounts of polymer sample used for LC separation and the quality of the MS results are equivalent to the "dry spray" method; however, three times more fractions were collected and analyzed with the newly developed hyphenated approach. The off-line method eliminates optimization of, for example, spray conditions or spreading of organic solvents on the MALDI plate that occurs with droplet deposition methods. The widespread applications of MALDI make this solvent-free, multisample method particularly important as it expands the capabilities for obtaining mass measurements with great efficiencies in areas with increased sample numbers. In addition, the solvent-free method is well suited for automated MALDI analysis as it virtually eliminates the "dead-spot" phenomenon.
本文描述了一种无溶剂均质化/转移基质辅助激光解吸/电离（MALDI）质谱（MS）方法，用于在单个MALDI板上同时制备和精确转移多达100个样品。使用由不同分子量（500 - 6000）和端基（聚环氧乙烷（PEO）、二甲氧基-PEO、单甲氧基单甲基丙烯酸酯-PEO和二甲基丙烯酸酯-PEO）组成的聚环氧乙烷（PEO）混合物对该方法进行了验证，该混合物在临界条件下通过液相吸附色谱进行了分馏。在进行靶上无溶剂样品制备和MALDI质量分析之前，先进行离线分馏。无溶剂MALDI方法的小型化使得每个分馏物中每种PEO组分的分析量小于2微克，对于PEO 6000约为200皮摩尔。用于液相色谱分离的聚合物样品量和质谱结果的质量与“干喷”方法相当；然而，采用新开发的联用方法收集和分析的分馏物数量增加了两倍。离线方法消除了例如喷雾条件的优化或液滴沉积方法中有机溶剂在MALDI板上的铺展。MALDI的广泛应用使得这种无溶剂、多样品方法尤为重要，因为它扩展了在样品数量增加的领域高效获取质量测量结果的能力。此外，无溶剂方法非常适合自动化MALDI分析，因为它几乎消除了“死区”现象。
