Pulsed Direct Current Electrospray: Enabling Systematic Analysis of Small Volume Sample by Boosting Sample Economy

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Metabolomics

Background:

• Analyzing small sample volumes, such as single cells, presents significant challenges in mass spectrometry due to limited analyte quantity.
• Traditional electrospray ionization methods often require larger sample volumes, hindering detailed analysis of micro-samples.
• The need for sensitive and comprehensive analytical techniques for single-cell studies is growing.

Purpose of the Study:

• To develop and validate a novel pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) method for analyzing minute sample volumes.
• To demonstrate the capability of pulsed-dc-ESI-MS for systematic profiling and component determination in picoliter samples.
• To apply the developed method for single-cell metabolomics analysis, generating detailed metabolite and saccharide profiles.

Main Methods:

• Development of a pulsed direct current electrospray ionization source generating single-polarity pulsed electrospray remotely.
• Optimization of pulsed-dc-ESI parameters to maximize signal duration from picoliter sample volumes.
• Application of the pulsed-dc-ESI-MS method for two-dimensional profiling (exact mass and MS(2) data) of metabolites in single plant (Allium cepa) and mammalian (HeLa) cells.

Main Results:

• Pulsed-dc-ESI significantly enhances sample economy, yielding minutes of MS signal from picoliter samples.
• The method enabled collection of abundant MS(2) data, facilitating systematic analysis of components in small volume samples.
• Analysis of single Allium cepa cells identified 1034 components, including 162 compounds and 28 modification groups of 141 saccharides.
• Analysis of single HeLa cells identified 656 components.

Conclusions:

• Pulsed direct current electrospray ionization mass spectrometry is a powerful and highly sensitive tool for systematic analysis of small volume samples.
• The method's ability to generate extensive MS(2) data from minimal sample amounts makes it ideal for single-cell metabolomics.
• This technique offers unprecedented insights into the molecular composition of individual cells.