Published July 7, 2022 | Version v1
Journal article Open

Effect of ion source polarity and dopants on the detection of auxin plant hormones by ion mobility‑mass spectrometry

  • 1. Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F2, 84248 Bratislava, Slovakia
  • 2. Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran


Ion mobility spectrometry (IMS) equipped with a corona discharge (CD) ion source was used for measurement of three auxin plant hormones including indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), and indole-3-butyric acid (IBA). The measurements were performed in both positive and negative polarities of the CD ion source. Dopant gases NH 3 , CCl 4 , and CHBr 3 were used to modify the ionization mechanism. A time-of-flight mass spectrometer (TOFMS) orthogonal to the IMS cell was used for identification of the product ions. Density functional theory was used to rationalize formation of the ions, theoretically. The mixtures of the auxins were analyzed by CD-IMS. The separation performance depended on  the ion polarity and the dopants. In the positive polarity without dopants, auxins were ionized via protonation and three distinguished peaks were observed. Application of NH 3 dopant resulted in two ionization channels, protonation, and NH 4+ attachment leading to peak overlapping. In the negative polarity, two ionization reactions were operative, via deprotonation and O 2− attachment. The separation of the monomer peaks was not achieved while the peaks of anionic dimers [2 M-H] − were separated well. The best  LOD (4 ng) was obtained in negative polarity with CCl 4 dopant. Methylation (esterification) of IAA improved LODs by about one order.



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PlantIMS – Fast and Sensitive Detection of Plant Hormones by Ion Mobility Spectrometry 101031538
European Commission