Aston Labs

DESI -- Ambient ionization applied to large and small molecules.

Desorption Electrospray Ionization (DESI) is able to analyze solid samples present on a surface with minimal to no sample preparation by spraying fast-moving charged solvent droplets onto sample surfaces. The analytes present on the surface are extracted and carried by the offspring droplets into the atmospheric pressure interface of the mass spectrometer where ions are produced through electrospray ionization mechanisms.

Analytical Performance of DESI

• Detection limits: Low picogram/high femtogram levels
• Mass range: 66 kDa (BSA)
• Quantitation: ~5-10% RSD using isotope labeled internal standards, ~10-20% using external calibration
• Sampling speed: 3 samples/sec
• Imaging spatial resolution: 500 μm (est.) on tissue, 250 μm printed lines

Analytical challenges of DESI

• Quantitation
• Matrix effects
• Analysis for non-polar, non-soluble species

DESI of different molecules

Publications:

• Zoltan Takats, Justin M. Wiseman, Bogdan Gologan, and R. Graham Cooks, "Mass Spectrometry Sampling Under Ambient Conditions with Desorption Electrospray Ionization" Science, 5695 (2004) 471-473. doi: 10.1126/science.1104404
• Justin M. Wiseman, Demian R. Ifa, Qingyu Song, R. Graham Cooks, "Tissue Imaging at Atmospheric Pressure using Desorption Electrospray Ionization(DESI) Mass Spectrometry", Angewandte Chemie International Edition , 2006, 45, 43, 7188-7192,doi: 10.1002/anie.200602449
• Ismael Cotte-Rodriguez, Zoltan Takats, Nari Talaty, Huanwen Chen, and R. Graham Cooks, "Desorption Electrospray Ionization of Explosives on Surfaces: Sensitivity and Selectivity Enhancement by Reactive Desorption Electrospray Ionization", Analytical Chemistry, 2005, 77(21), 6755-6764,doi: 10.1021/ac050995+
• Yishu Song, Nari Talaty, Andy W. Tao, Zhengzheng Pan and R. Graham Cooks, "Rapid Ambient Mass Spectrometric Profiling of Intact, Untreated Bacteria using Desorption Electrospray Ionization", Chemical Communications , 2007, 61-63, doi: 10.1039/b615724f