Desorption ionization by charge exchange (DICE) for sample analysis under ambient conditions by mass spectrometry.
An ambient pressure ionization technique for mass spectrometric analysis of substances present on solid surfaces was developed. A nebulized spray containing molecular ions of a solvent such as toluene can be generated by passing the solvent through a stainless steel capillary held at a high voltage. When the stream of charged droplets produced in this way is directed onto a solid surface, the analytes present on the surface are desorbed and ionized by a charge exchange process. This technique was shown to desorb and generate positively charged molecular ions from compounds that are not readily ionized by some other ambient methods, under positive-ion generation mode. For example, intense signals representing radical cations of 1,4-hydroquinone, limonene, thymol, and several other compounds were observed when the analytes were deposited on a metal surface and exposed to a toluene spray nebulized from the metal capillary maintained at a potential of about +5 kV. In contrast, when the same samples were exposed to a spray of water/methanol/formic acid under customary DESI-like (positive-ion mode) conditions, no peaks representing the analytes were observed.
Chan
Chang-Ching
CC
Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
Bolgar
Mark S
MS
Miller
Scott A
SA
Attygalle
Athula B
AB
D001274:Atmospheric Pressure; D053138:Cyclohexenes / Q000032:analysis / Q000737:chemistry; D006873:Hydroquinones / Q000032:analysis / Q000737:chemistry; D000077222:Limonene; D009330:Nebulizers and Vaporizers; D009930:Organic Chemicals / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013193:Stainless Steel / Q000737:chemistry; D013729:Terpenes / Q000032:analysis / Q000737:chemistry; D013943:Thymol / Q000032:analysis / Q000737:chemistry
D053138:Cyclohexenes; D006873:Hydroquinones; D009930:Organic Chemicals; D013729:Terpenes; D013193:Stainless Steel; D013943:Thymol; D000077222:Limonene; C031927:hydroquinone