Propan 2 ol

d-(+)-glucose, d-(−)-fructose, and quinine sulfate were purchased from Sigma-Aldrich (Saint-Quentin-Fallavier, France). Ultrapure water (Milli-Q purification system, Millipore, France) and HPLC grade solvent (acetonitrile, ethanol, ethyl acetate, n-heptane, methanol, and propan-2-ol; VWR International, Pessac, France) were used for sample preparation and lignan purification. acetonitrile (ACN) and water used for chromatographic separation were LC-MS grade and were purchased from Fisher Chemical (Illkirch, France). Lignans were isolated as previously described by Marchal et al. [26 (link)].

Propan-2-ol (analytical grade) and n-heptane (analytical grade) were purchased from VWR Chemicals (Radnor, PA, USA) and methanol (HPLC grade) was purchased from Fisher Chemicals (Hampton, NH, USA). Bidistilled water was freshly produced with a distillation apparatus from Heraeus-Quarzschmelze GmbH (Hanau, Germany) in the laboratory. Caffeine (> 99.9% chemical purity) and ¹³C₃-Caffeine standard solution (1 mg/mL in methanol, 99 atom % ¹³C, > 99% chemical purity) were obtained from Merck KGaA (Darmstadt, Germany). The used HPTLC plates including C18 reversed-phase (RP)-HPTLC LiChrospher®, NP-HPTLC, and cyano (CN)-modified HPTLC were all provided by Merck KGaA (Darmstadt, Germany). Microscope slides were acquired from Carl Roth GmbH + Co. KG (Karlsruhe, Germany), and uncoated TLC glasses were used from MACHEREY–NAGEL (Düren, Germany). Red Bull, Coca-Cola, coffee, and black tea as Caffeine-containing beverages were obtained from local grocery stores.

All chemicals were purchased
and used without further purification.
Propan-2-ol (C₃H₈O, ≥99.5%), ethanol
(EtOH, ≥99.8%), methanol (MeOH, ≥99.5%), acetone (C₃H₆O, ≥99.5%), and hydrochloric acid (HCl,
37.0%) were purchased from VWR. Nitric acid (HNO₃, ≥65%),
sodium hydroxide pellets (NaOH, ≥98.0%), sodium borohydride
(NaBH₄, ≥97%), and l(+)-ascorbic acid (AA,
≥99%,) were purchased from Carl Roth. Hydrogen tetrachloroaurate
trihydrate (HAuCl₄·3H₂O, ≥99.9%),
hexadecyltrimethylammonium bromide (CTAB ≥99%), cetyltrimethylammonium
chloride solution (CTAC, 25 wt % in H₂O), hexadecylpyridinium
chloride monohydrate (CPC, 99.0–102.0%), (3-aminopropyl)triethoxysilane, N,N-diisopropylethylamine (DIPEA), and
poly(sodium 4-styrenesulfonate, M_w of
70000 g/mol) were purchased from Sigma-Aldrich. 3-(Triethoxysilyl)propylsuccinic
anhydride, 3-acetoxypropyltrimethoxysilane, n-butyltriethoxysilane, and heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane
were purchased from abcr. (α-Thiol, ω-bromo)-terminated
poly(acrylic acid) (PAA-SH, M_w of 8500
g/mol) was purchased from Polymer Source Inc. Mica sheets were obtained
from Micro to Nano with different shapes and a thickness of 0.15 to
0.21 mm and the highest grade V-1 quality. Double-polished Si wafers
(orientation [100] of 5 mm length and 7 mm width) from Siegert Wafer
were used for ellipsometry measurements. Milli-Q water (18.2 MΩ·cm)
was used in all experiments.