Related Experiment Video
Updated: Jun 12, 2026
09:22
Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry
Published on: September 3, 2010
Inline pneumatically assisted atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass
Arti T Navare1, Facundo M Fernández
1School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Journal of Mass Spectrometry : JMS
|June 8, 2010
Summary
A new coaxial gas flow ion source for atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) significantly improves ion transfer. This method enhances sensitivity and signal-to-noise ratios for peptide and drug analysis.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Chemical Physics
Background:
- Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) typically exhibits lower ion transfer efficiency than vacuum MALDI (vMALDI).
- Challenges in ion transport limit sensitivity and signal quality in AP-MALDI applications.
Purpose of the Study:
- To develop and evaluate a novel AP-MALDI ion source design using coaxial gas flow to enhance ion transfer efficiency.
- To investigate the impact of different carrier gases and flow rates on analyte signal intensity and signal-to-noise ratios.
Main Methods:
- A new AP-MALDI ion source incorporating coaxial gas flow was designed and implemented.
- Nitrogen, helium, and sulfur hexafluoride were tested as carrier gases for analyzing peptide and small molecule standards.
- Ion transport efficiency, sensitivity, limits of detection, and signal-to-noise ratios were quantified under varying conditions, including continuous and pulsed target plate voltages.
Main Results:
- Nitrogen gas demonstrated superior ion transport efficiency, yielding sensitivity gains of up to 1900% and 20% for a peptide standard.
- The coaxial gas flow effectively entrained ions, deflected background species, and reduced analyte-matrix adducts, improving absolute signal intensity and signal-to-noise (S/N) ratios.
- Limits of detection for angiotensin I were improved to 20 or 3 femtomoles with pneumatically assisted (PA) AP-MALDI under continuous or pulsed target plate voltage, respectively. Low gas flow rates (0.3-0.6 L/min) were optimal for low-mass analytes to minimize fragmentation.
Conclusions:
- The developed pneumatically assisted (PA) AP-MALDI source with coaxial gas flow significantly enhances ion transfer and sensitivity compared to conventional AP-MALDI.
- Carrier gas selection, flow rate, analyte properties, and extraction field characteristics are critical factors influencing the performance of this novel ion source.
More Related Videos
Related Concept Videos
01:08Matrix-Assisted Laser Desorption Ionization (MALDI)
Matrix-assisted laser desorption ionization (MALDI) is a powerful analytical technique used in mass spectrometry. It enables the identification and characterization of various biomolecules, including proteins, peptides, nucleic acids, and carbohydrates. MALDI is an ionization technique, widely employed in biological and medical research, as well as in fields like pharmacology and biochemistry.The analyte of interest, a biomolecule or a mixture of biomolecules, is mixed with a suitable matrix...
01:19MALDI-TOF Mass Spectrometry
Mass spectrometry is a powerful characterization technique that can identify and separate a wide variety of compounds ranging from chemical to biological entities, based on their mass-to-charge ratio (m/z). The instruments that allow this detection, known as mass spectrometers, have three components: an ion source, a mass analyzer, and a detector. These spectrometers differ based on the nature of their ion source and analyzers.Matrix-assisted laser desorption ionization (MALDI) is a commonly...
01:19Inductively Coupled Plasma–Mass Spectrometry (ICP–MS): Overview
In inductively coupled plasma–mass spectrometry (ICP–MS), an inductively coupled plasma (ICP) torch is used as an atomizer and ionizer. Solid samples are dissolved and volatilized before being introduced into the high-temperature argon plasma, while solution samples are nebulized and passed through the high-temperature argon plasma. Plasma dissociates the analytes and ionizes their component atoms to form a mixture of positive ions and molecular species. The positive ions are then passed on to...
01:24Mass Spectrum: Interpretation
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a soft-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.To...
01:21Tandem Mass Spectrometry
Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and reduce chemical noise during analyte detection. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called...
01:19Mass Analyzers: Common Types
The quadrupole mass analyzer consists of four cylindrical metal rods arranged in a diamond carrying a DC voltage and a radio-frequency AC voltage. The motion of ions through the quadrupole depends on the field strength, causing only ions of a certain m/z to resonate successfully and strike the detector at a given field strength. Though the transmission rate for these analyzers is high, the exact elemental composition of the sample is not determined because of low resolution; however, they are...