Faculty of Engineering, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi 400-8511, Japan.
J Am Soc Mass Spectrom. 2021 Jul 7;32(7):1821-1828. doi: 10.1021/jasms.1c00157. Epub 2021 Jun 24.
We investigated the electrospray ionization inside the narrow channel of the ion inlet tube. An insulating emitter capillary made of fused silica with a 0.2 mm outer diameter was inserted into the ion inlet tubes with a 0.5 and 0.6 mm inner diameter to aspirate all the charged droplets. A custom-made ion inlet tube with two side holes near its entrance is used to observe the spraying condition. The spray current is measured and monitored during the MS acquisition using isolation amplifiers. Because the emitter is cylindrically surrounded in close proximity by the metallic inner wall, it is difficult to obtain a stable and symmetric Taylor cone with its apex at the center of the emitter. Instead, a stable operation under a flow rate of 1-4 μL/min is found to be in the form of a multicone-jet mode with two or more Taylor cones anchoring around the rim of the emitter. The emitted charged droplet jets are dragged from hitting the wall by the fast-flowing air inside the inlet tube. Comparison with the typical cone-jet and multijet mode operated several millimeters outside the inlet capillary shows signal enhancements for protein standards.
我们研究了离子入口管狭窄通道内的电喷雾电离。将外径为 0.2 毫米的熔融石英制成的绝缘发射毛细管插入内径为 0.5 和 0.6 毫米的离子入口管中，以吸取所有带电液滴。使用带有两个侧孔的定制离子入口管在其入口附近观察喷雾条件。使用隔离放大器在 MS 采集过程中测量和监测喷雾电流。由于发射器被金属内壁紧密地圆柱状包围，因此很难获得一个稳定且对称的泰勒锥，其顶点位于发射器的中心。相反，在 1-4 μL/min 的流速下找到稳定的操作是以双锥-射流模式的形式，其中两个或更多个泰勒锥围绕发射器边缘固定。发射的带电液滴射流由于入口管内快速流动的空气而从撞击壁上被拖曳。与在入口毛细管外几毫米处操作的典型锥-射流和多射流模式进行比较，显示出蛋白质标准品的信号增强。
