Desorption atmospheric pressure photoionization and direct analysis in real time coupled with travelling wave ion mobility mass spectrometry

• Published in: Rapid communications in mass spectrometry 2014-11, Vol.28 (21), p.2325-2336
• Main Authors: Räsänen, Riikka-Marjaana, Dwivedi, Prabha, Fernández, Facundo M., Kauppila, Tiina J.
• Format: Article
• Language: English
• Subjects: Atmospheric Pressure; Bisphenol A; Dried Blood Spot Testing; Humans; Ion mobility; Ionic mobility; Mass spectrometry; Mass Spectrometry - methods; Organic Chemicals - analysis; Organic Chemicals - chemistry; Photochemical Processes; Separation; Signal-To-Noise Ratio; Tablets; Tablets - chemistry; Traveling waves
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.7028

RATIONALE Ambient mass spectrometry (MS) is a tool for screening analytes directly from sample surfaces. However, background impurities may complicate the spectra and therefore fast separation techniques are needed. Here, we demonstrate the use of travelling wave ion mobility spectrometry in a comparative study of two ambient MS techniques. METHODS Desorption atmospheric pressure photoionization (DAPPI) and direct analysis in real time (DART) were coupled with travelling wave ion mobility mass spectrometry (TWIM‐MS) for highly selective surface analysis. The ionization efficiencies of DAPPI and DART were compared. Test compounds were: bisphenol A, benzo[a]pyrene, ranitidine, cortisol and α‐tocopherol. DAPPI‐MS and DART‐TWIM‐MS were also applied to the analysis of chloroquine from dried blood spots, and α‐tocopherol from almond surface, and DAPPI‐TWIM‐MS was applied to analysis of pharmaceuticals and multivitamin tablets. RESULTS DAPPI was approximately 100 times more sensitive than DART for bisphenol A and 10–20 times more sensitive for the other compounds. The limits of detection were between 30–290 and 330–8200 fmol for DAPPI and DART, respectively. Also, from the authentic samples, DAPPI ionized chloroquine and α‐tocopherol more efficiently than DART. The mobility separation enabled the detection of species with low signal intensities, e.g. thiamine and cholecalciferol, in the DAPPI‐TWIM‐MS analysis of multivitamin tablets. CONCLUSIONS DAPPI ionized the studied compounds of interest more efficiently than DART. For both DAPPI and DART, the mobility separation prior to MS analysis reduced the amount of chemical noise in the mass spectrum and significantly increased the signal‐to‐noise ratio for the analytes. Copyright © 2014 John Wiley & Sons, Ltd.