Article Highly hydrophobic properties in olive oil-coated papers through thermal treatment Amelia Loesch-Zhang1, Tobias Meckel1, Markus Biesalski1 and Andreas Geissler1,2* Supporting information Protocol for gas chromatography–mass spectrometry/flame ionization detector (GC- MS/FID) GC-MS/FID measurements were performed on an Agilent HP 6890 gas chromato- graph (Agilent Technologies Deutschland GmbH, Waldbronn, Germany) equipped with parallel mass detection and flame ion detection. Separation was carried out on a VF5MS- 60M column (Agilent Technologies Deutschland GmbH, Waldbronn, Germany) (inner di- ameter 0.25 mm, film thickness 0.25 µm). The injection was performed using an HP PTV injector at 573.15 K, split ratio 15:1 and 1 µL injection volume. Helium was used as carrier gas (2 mL/min flow rate). Online methylation of olive oil was required to transfer fatty acids into the gas phase. For this, oils were added to dichloromethane (5.59 mg oil per mL dichloromethane) to- gether with a solution of fluoranthene in dichloromethane (2 g/mL, 100 µL) as an internal standard and trimethylsulfonium hydroxide (400 µL) trimethylsulfonium hydroxide. The following temperature program was used: holding at 318.15 K (4 min), heating to 478.15 K (3 K/min), holding at 478.15 K (13 min), heating to 598.15 K (3 K/min), holding at 598.15 K (20 min). For the evaluation, FID signals were calibrated against methylated standards. Mass fractional content of methylated fatty acids was calculated relative to unmethylated fatty acids based on their respective molecular weights. 4000 3000 2000 1000 Cotton linters Fresh, extracted cotton linters 70°C, extracted cotton linters Tr an sm itt an ce (a . u .) Wavenumber (cm-1) Figure S1. Full ATR-FTIR spectrum of extracted cotton linters after varying aging processes showing a small C=O band indicating esterification exclusively after thermal aging. License: CC BY 4.0 International - Creative Commons, Attribution https://creativecommons.org/licenses/by/4.0/ Figure S2. Full NMR spectra of olive oil extracted from cotton linters (fresh and after aging). 4000 3000 2000 1000 Fresh Norm climate 70°C Ar Tr an sm itt an ce (a . u .) Wavenumber (cm-1) Figure S3. ATR-FTIR spectra normalized to C=O peak intensity of freshly olive oil-coated cotton linter paper and aged under different conditions.