Effects of Inlet Capillary Temperature in Atmospheric-Pressure Infrared Laser-Ablation Plasma Postionization Mass...

Area of Science:

• Analytical Chemistry
• Biotechnology
• Mass Spectrometry Imaging

Background:

• Mass spectrometry imaging (MSI) enables molecular surveys of biological surfaces.
• Atmospheric-pressure (AP) infrared laser-ablation plasma postionization (IR-PPI) offers matrix-free analysis of small molecules in tissues.
• Ion intensity in AP-MSI modalities is highly dependent on inlet capillary temperature.

Purpose of the Study:

• To investigate the relationship between detected ion intensity and inlet capillary temperature in IR-PPI.
• To determine optimal temperature ranges for various analytes across different substrates and tissue types.
• To demonstrate the impact of inlet temperature control on the interpretation of tissue MSI data.

Main Methods:

• Evaluated ion intensity versus inlet capillary temperature (room temperature to 650 °C) for analytes on various substrates and tissues (fresh frozen, FFPE) using IR-PPI.
• Analyzed temperature dependencies for exemplar ions, including lactate, glutamine, arachidonic acid, and PI(18:0/20:4).
• Applied uniform manifold approximation and projection (UMAP) and k-means clustering for data reduction and trend analysis.

Main Results:

• Observed diverse optimal temperatures for different ions, ranging from ~100 °C for lactate to ~500 °C for PI(18:0/20:4).
• Demonstrated distinct temperature dependencies for various molecular species.
• Showcased critical differences in glucose and lactate ion intensities in mouse brain MSI based on inlet temperature settings.

Conclusions:

• Inlet capillary temperature is a critical variable influencing ion detection and data interpretation in AP-MSI.
• Tailoring temperature settings is essential for optimizing sensitivity and specificity for different analytes in tissue MSI.
• Precise temperature control is vital for reproducible and accurate molecular profiling of biological samples using IR-PPI.