On-demand ambient ionization of picoliter samples using charge pulses

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Separation Science

Background:

• Traditional electrospray ionization (ESI) methods face limitations in throughput and sample volume.
• Developing sensitive and rapid ionization techniques is crucial for high-throughput screening.

Purpose of the Study:

• To introduce and characterize relay electrospray ionization (rESI) as a novel technique for efficient sample ionization.
• To demonstrate the capability of rESI for high-throughput analysis of diverse analytes.

Main Methods:

• Utilized charge deposition to trigger rESI from sample-loaded capillaries.
• Employed primary ion sources including plasma ion and piezoelectric discharge plasma sources.
• Investigated rESI for both polar and nonpolar analytes using optimized secondary capillary configurations.

Main Results:

• Achieved high-throughput sample screening with no physical contact required.
• Demonstrated ionization of sub-pL sample volumes for polar analytes like neurotransmitters and phosphopeptides.
• Showcased successful ionization of nonpolar analytes such as steroids and alkynes.
• Reported concentration sensitivities comparable to nanoESI, but with orders of magnitude better absolute sensitivity.

Conclusions:

• rESI offers a powerful platform for rapid, sensitive, and low-volume analysis.
• The technique is versatile, capable of ionizing a wide range of polar and nonpolar compounds.
• rESI significantly advances capabilities in high-throughput screening for various scientific applications.