Does the Formation\nof a Taylor Cone in a Pulsating\nElectrospray Directly Impact Mass Spectrometry Signals?

Electrospray ionization (ESI) remains the dominant technique\nin\nmass spectrometry (MS)-based analyses. Here, we investigated the relationship\nbetween a crucial aspect of ESI, the formation of the Taylor cone,\nand the MS ion current by utilizing a triple quadrupole (QqQ) mass\nspectrometer coupled with a streaming high-speed camera and a 3-ring\nelectrode system. In one test, ion current over a 30-s plume gate\n(a ring electrode) opening was compared with the Taylor cone occurrence\nanalyzed offline, with Spearman’s correlation coefficients\nconsistently near 0 despite parameter variations. In another test,\nreal-time detection of Taylor cones was synchronized with QqQ-MS,\nselectively opening (de-energizing) the plume gate based on the Taylor\ncone status. This approach enabled matching the ion current with the\nTaylor cone occurrence. There was no apparent difference between the\nMS signals recorded in the presence and absence of a Taylor cone.\nAdditionally, a Faraday plate was employed as a detector in offline\nexperiments, revealing agreement between the frequency of liquid meniscus\n(Taylor cone) oscillation (∼1.92 kHz)measured by high-speed\nimagingand the frequency of spray current (∼1.93 kHz).\nWe suggest that the lack of positive correlations in the MS experiments\nis due to intrinsic ion carryover during transit from the ion source\nto the detector and due to the insufficient data acquisition rate\nof the mass spectrometer, which erases short-term fluctuations of\nion current.