TY - JOUR A1 - Warschat, Carsten A1 - Stindt, Arne A1 - Panne, Ulrich A1 - Riedel, Jens T1 - Mass spectrometry of levitated droplets by thermally unconfined infrared-laser desorption T2 - Analytical Chemistry N2 - An ionization scheme for fast online mass spectrometric interrogation of levitated droplets is presented. That renewed method comprises the output of an a Er:YAG laser at λ = 2.94 µm which is in resonance with the OH stretch vibration band of solvents like water and alcohols. A temporal pulse width larger than the time needed for pressure redistribution and also above the temperature redistribution time constant was found to lead to soft evaporation/ionization. Despite these mild desorption conditions, no additional postionization is found to be needed. Accordingly, the ionization is found to be very soft resulting in entirely intact analyte ions and concentration dependent cluster ions. Resulting mass spectra of small amino acids and large antibiotics are presented showing the versatility of the introduced technique. Above a critical mass of m ≈ 1 kDa, the formed ions carry multiple charges as it is typical for thermospray or electrospray ionization. The detection technique enables fast contactless analysis of the chemical composition of levitated microreactors and, thus, paves the way for future contactless reaction monitoring. PB - American Chemical Society CY - Washington, DC KW - Laser desorption ionization KW - Levitated droplets KW - Ambient mass spectrometry PY - 2015 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/35134 AN - OPUS4-35134 SN - 0003-2700 SN - 1520-6882 VL - 87 IS - 16 SP - 8323 EP - 8327 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany