Aerosol Desorption Electrospray Ionization

From Murray Mass Spectrometry Group

MP6 - Presented at the 55th ASMS Conference on Mass Spectrometry, June 3 - 7, 2007, Indianapolis, Indiana

Aerosol Desorption Electrospray Ionization (PDF)

Jianan Dong, Yohannes H. Rezenom, and Kermit K. Murray

Louisiana State University, Baton Rouge, Louisiana

Contents 1 Introduction 1.1 Goal 1.2 Approach 2 Background 2.1 Related ionization methods 2.2 Advantages of direct ionization 3 Experimental 3.1 Instrumentation 3.2 Dry particle DESI 3.3 IR laser desorption electrospray ionization (IR LDESI) 4 Conclusions 5 Future Work 5.1 Dry particles 5.2 IR LDESI 6 Acknowledgements

Introduction

Goal

Dry and laser desorbed aerosol particles by desorption electrospray ionization (DESI)

Approach

• Aerosol particle generation
• Dry particles (fluidized bed aerosol generator)
• Infrared laser ablated particles
• Nano-electrospray source
• Ion trap mass spectrometer

Background

Related ionization methods

• DESI (Cooks; Ouyang; Takats; Wiseman Science 2006, 311, 1566)
• ELDI (Shiea; Huang; Hsu; Lee; Yuan; Beech; Sunner J.Rapid Commun. Mass Spectrum. 2005, 19, 3701)
• MALDESI (Sampson; Hawkridge; Muddiman J. Am. Soc, Mass Spectrom. 2006, 17, 1712)
• FD-ESI (Chang; Lee; Shiea Anal. Chem. 2002, 74, 2465)

Advantages of direct ionization

• No sample pre-treatment
• Rapid analysis
• High throughput
• Difficulties of analyzing large molecule particles

Experimental

Instrumentation

• Hitachi M-8000 ion trap
• TSI 3400A fluidized bed aerosol generator
• New Objective PV-300 nanospray

Dry particle DESI

• 500 nl/min solvent (1:1 Acetonitrile:H₂O + 0.1% formic acid) flow rate
• 2.0 kV high voltage
• Nitrogen pneumatic gas 0.2 kgf/cm²

IR laser desorption electrospray ionization (IR LDESI)

• 500 nl/min solvent (1:1 Methanol:H₂O + 0.1% acetic acid) flow rate
• 0.3 µl analytes on the sample target
• 2.5 kV high voltage
• No pneumatic gas nanospray
• 1 mJ laser energy
• Analyte in water

Conclusions

• Dry particles
• No sample treatment
• Protonated molecule observed
• Ionization mechanism appears to be aerosol DESI
• Infrared laser desorption
• Water matrix
• High mass protein ionization
• Direct analysis of biofluidic samples

Future Work

Dry particles

• Environmental analysis
• Bioaerosols

IR LDESI

• Tissue imaging
• Forensics

Acknowledgements

• National Science Foundation (CHE-0415360)
• Alex Tchapyjnikov, Infrared Fiber Systems