Schneider Bradley B, Javaheri Hassan, Covey Thomas R
MDS SCIEX, Concord, ON, Canada.
Rapid Commun Mass Spectrom. 2006;20(10):1538-44. doi: 10.1002/rcm.2511.
The motivation of this work was to study some of the properties of nanoelectrospray operation under conditions where the entire sprayed liquid is vaporized and inhaled into the vacuum system. Under these conditions the desolvation requirements, sampling efficiency, concentration versus mass sensitivity, and molar response characteristics of various compounds were studied. The combined efficiency of ion production from solution and transfer into the vacuum system, referred to as sampling efficiency, is presented under various inlet conditions including different flow rates, solution compositions, and compound types. Under ideal solvent conditions the results for favorable compounds show sampling efficiencies of 70-85% at flows in the range of 50-500 nL/min. Efficiencies were lower for aqueous samples and compounds of different structures gave different molar response factors under these high sampling efficiency conditions. The relative molar response factors are presented in terms of those observed with higher flow rate sources which operate at significantly lower sampling efficiencies. In all cases, operating in this flow regime, the ion count rate was directly proportional to the absolute mass of analyte molecules entering the source. The experimental source used to carry out these studies included gas nebulization to stabilize the electrospray process, a heated laminar flow chamber to enhance desolvation and ion production, and various atmosphere-to-vacuum aperture diameters to maximize ion transfer.
这项工作的目的是研究在整个喷雾液体被蒸发并吸入真空系统的条件下，纳米电喷雾操作的一些特性。在这些条件下，研究了各种化合物的去溶剂化要求、采样效率、浓度与质量灵敏度以及摩尔响应特性。从溶液中产生离子并转移到真空系统的综合效率，即采样效率，在包括不同流速、溶液组成和化合物类型在内的各种入口条件下进行了展示。在理想的溶剂条件下，对于有利的化合物，在流速为50 - 500 nL/min范围内，采样效率为70 - 85%。对于水性样品，效率较低，并且在这些高采样效率条件下，不同结构的化合物给出不同的摩尔响应因子。相对摩尔响应因子是以在显著较低采样效率下运行的较高流速源所观察到的因子来表示的。在所有情况下，在这种流动状态下运行时，离子计数率与进入源的分析物分子的绝对质量成正比。用于进行这些研究的实验源包括用于稳定电喷雾过程的气体雾化、用于增强去溶剂化和离子产生的加热层流室，以及用于最大化离子转移的各种大气到真空孔径直径。
