Western Michigan University, Kalamazoo, MI, USA.
J Am Soc Mass Spectrom. 2012 Nov;23(11):1896-902. doi: 10.1007/s13361-012-0468-x. Epub 2012 Aug 21.
Spray desorption collection (SDC) and reflective electrospray ionization (RESI) were used to independently study the desorption and ionization processes that together comprise desorption electrospray ionization (DESI). Both processes depend on several instrumental parameters, including the nebulizing gas flow rate, applied potential, and source geometries. Each of these parameters was optimized for desorption, as represented by the results obtained by SDC, and ionization, as represented by the results obtained by RESI. The optimized conditions were then compared to the optimization results for DESI. Our results confirm that optimal conditions for desorption and ionization are different and that in some cases the optimized DESI conditions are a compromise between both sets. The respective results for DESI, RESI, and SDC for each parameter were compared across the methods to draw conclusions about the contribution of each parameter to desorption and ionization separately and then combined within DESI. Our results indicate that desorption efficiency is (1) independent of the applied potential and (2) the impact zone to inlet distance, and that (3) gas pressure settings and (4) sprayer to impact zone distances above optimal for DESI are detrimental to desorption but beneficial for ionization. In addition, possible interpretations for the observed trends are presented.
喷雾解吸收集（SDC）和反射式电喷雾电离（RESI）被用于分别研究解吸和电离过程，这两个过程共同构成了解吸电喷雾电离（DESI）。这两个过程都依赖于几个仪器参数，包括雾化气流速、施加的电势和源几何形状。每个参数都针对解吸进行了优化，这由 SDC 得到的结果表示，而针对电离进行了优化，这由 RESI 得到的结果表示。然后将优化条件与 DESI 的优化结果进行了比较。我们的结果证实，解吸和电离的最佳条件是不同的，在某些情况下，优化的 DESI 条件是两者之间的妥协。对于每个参数，分别在 DESI、RESI 和 SDC 之间比较了各自的结果，以便得出关于每个参数对解吸和电离的单独贡献的结论，然后再将其结合在 DESI 中。我们的结果表明，解吸效率（1）独立于施加的电势，（2）影响区域到入口的距离，并且（3）DESI 最佳气压设置和（4）喷雾器到影响区域的距离对解吸不利，但对电离有利。此外，还提出了对观察到的趋势的可能解释。
