Apparent penetration depth in attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy of Allium cepa L. epidermis and cuticle

Autor(en)

Alexander Götz, Ramin Nikzad-Langerodi, Yannick Städler, Anke Bellaire, Johannes Saukel

Abstrakt

Over the past decades, ATR-FTIR has emerged as promising tool for the identification of plants at the genus and (sub-) species level through surface measurements of intact leaves. Theoretical considerations regarding the penetration depth of the evanescent wave into the sample and the thickness of plant leaf cuticles suggest that the structure and composition of the cuticle represent universal taxonomic markers. However, experimental evidence for this hypothesis is scarce. In the current contribution, we present results of a series of simple experiments on epidermal monolayers derived from the bulbs of Allium cepa L. (Amaryllidaceae) as a model system to study the effect of an IR active probe located beyond the theoretical penetration depth of the evanescent wave. We found that this probe had a significant influence on the ATR-FTIR spectra for up to 4 epidermal layers stacked on top of each other corresponding to a total thickness of around 60 μm, exceeding the theoretical penetration depth of the evanescent wave by a factor of around 20. Altogether, our data indicate a major discrepancy between theory and practice in ATR-FTIR spectroscopy in general and provide strong evidence that in general plant leaf spectra cannot be fully explained by the structure and composition of the cuticle alone.

Organisation(en)

Department für Botanik und Biodiversitätsforschung, Department für Funktionelle und Evolutionäre Ökologie

Externe Organisation(en)

Universität Wien, Research Center for Non Destructive Testing (RECENDT)

Journal

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Band

224

Anzahl der Seiten

6

ISSN

1386-1425

DOI

https://doi.org/10.1016/j.saa.2019.117460

Publikationsdatum

01-2020

Peer-reviewed

Ja

ÖFOS 2012

106008 Botanik, 106012 Evolutionsforschung, 106042 Systematische Botanik

Schlagwörter

ASJC Scopus Sachgebiete

Analytical Chemistry, Instrumentation, Atomic and Molecular Physics, and Optics, Spectroscopy

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/apparent-penetration-depth-in-attenuated-total-reflection-fouriertransform-infrared-atrftir-spectroscopy-of-allium-cepa-l-epidermis-and-cuticle(69127d3d-61bf-4d66-9291-96a119a646b5).html