A heated capillary inlet for an electrospray ionization mass spectrometry (ESI-MS) interface was compared with shorter versions of the inlet to determine the effects on transmission and ionization efficiencies for low-flow (nano) electrosprays. Five different inlet lengths were studied, ranging from 6.4 to 1.3 cm. As expected, the electrospray current transmission efficiency increased with decreasing capillary length due to reduced losses to the inside walls of the capillary. This increase in transmission efficiency with shorter inlets was coupled with reduced desolvation of electrosprayed droplets. Surprisingly, as the inlet length was decreased, some analytes showed little or no increase in sensitivity, while others showed as much as a 15-fold gain. The variation was shown to be at least partially correlated with analyte mobilities, with the largest gains observed for higher mobility species, but also affected by solution conductivity, flow rate, and inlet temperature. Strategies for maximizing sensitivity while minimizing biases in ion transmission through the heated capillary interface are proposed.

将用于电喷雾电离质谱 (ESI-MS) 接口的加热毛细管入口与较短版本的入口进行比较，以确定对低流量（纳米）电喷雾的传输和电离效率的影响。研究了五种不同的入口长度，范围从 6.4 到 1.3 厘米。正如预期的那样，由于毛细管内壁的损失减少，电喷雾电流传输效率随着毛细管长度的减少而增加。入口较短时传输效率的提高与电喷雾液滴的去溶剂化减少相结合。令人惊讶的是，随着进样口长度的减少，一些分析物的灵敏度几乎没有增加或没有增加，而另一些则显示出高达 15 倍的增益。该变化至少部分与分析物的迁移率相关，流动性较高的物质的增益最大，但也受溶液电导率、流速和入口温度的影响。提出了最大化灵敏度同时最小化通过加热毛细管界面的离子传输偏差的策略。