Regarding Emitter Positioning for Nanoflow Electrospray Ionization with a High-Capacity Inlet Capillary

Nanoflow electrospray ionization is commonly used for
proteomics
due to its high sensitivity. Signal intensity, however, is dependent
on optimal emitter positioning relative to the mass spectrometer inlet.
Here, we characterize the effect of varied emitter positions on peptide
signal intensity in all three dimensions using emitters and flows
consistent with standard proteomic analyses. We observe improved signal
robustness to x/y variations at
increasing z distances and demonstrate that positioning
within 1 to 2 mm of the optimal location will maintain consistent
signal. Signal intensity behavior is consistent across the m/z range, suggesting emitter positions
do not need to be fine-tuned for different analytes for proteomics
analyses. These results provide insight for proteomics researchers
using nanoflow LC–MS/MS.