Dimethyl sulphide

The TD-GC-qMS method development was done using dimethyl sulphide (1, anhydrous, ≥ 99%), 2-methylbutanal (2, 95%), dimethyl disulphide (3, ≥ 98%), 2-hexanone (4, analytical standard), 1-octanol (6, anhydrous, ≥ 99%), 2-nonanone (7, ≥ 99%), 1-undecene (8, 97%), 1-decanol (9, ≥ 9 8%) and 2-aminoacetophenone (10, analytical standard) purchased from Sigma-Aldrich (Taufkirchen, Germany), and 2-heptanone (5, ≥ 98%) purchased from Merck KGaA (Darmstadt, Germany).
To verify the analysis of cyclic siloxanes by atmospheric pressure ionization (APPI), coupled with thermogravimetry (TG) and a qMS, three cyclic siloxanes were analysed as single standards. Octamethylcyclotetrasiloxane (D4, 98%, Alfa Aesar, Karlsruhe, Germany), decamethylcyclopentasiloxane (D5, 97%, Alfa Aesar, Karlsruhe, Germany) and dodecamethylcyclohexasiloxane (D6, 95%, Alfa Aesar, Karlsruhe, Germany) were used.
For all purposes, liquid chromatography-mass spectrometry (LC-MS) grade methanol from VWR (Leuven, Belgium) and ultrapure water, generated with a water purification system from Sartorius Stedim (Göttingen, Germany), were used. For cleaning purpose, Decon 90 from VWR (Leuven, Belgium) was used.

Reference standards (+) -β-Pinene (≥98.5%), 1-Octen-3-ol, borneol (≥95%), butyric acid (≥99.5%), citral (≥95%), cis-3-hexen-1-ol (≥98%), diacetyl, dimethyl sulphide, dimethyl trisulphide (≥98.5%), 3-methylbutanal (≥97%), 2-methylbutanal (≥95%), ethyl 2-methylbutanoate (99%), ethyl 2-methylpentanoate (internal standard, ≥99%), ethyl-3-methylbutanoate (≥98%), 3-methylbutyl-2-methylpropanoate (≥98%), 2-methylbutyl-2-methylpropanoate (≥95%), and ethyl cinnamate (99%), ethyl 2-methylpropanoate (≥99%), ethyl 3-methylbutanoate (≥98%), ethyl 4-methylpentanoate (≥97%), ethyl butanoate (≥99,5%), ethyl hexanoate (≥99.5%), eugenol (99.6%), furaneol (≥99%), geraniol (≥99%), hexanol (≥99%), 3-methylbutyl acetate (≥97%), linalool (97%), menthol (99%), methyl nonanoate (≥99.8%), myrcene (≥90%), geranyl acetate (≥97%), dimethyl disulphide (≥90%), limonene (97%), hexanal (≥98%), 3-hexenol (≥95%), 2-phenyl ethanol (≥99%), β-caryophyllene (≥80%), α-humulene (≥96%), humulene oxide, S-methyl 5-methylpentanthioate S-methyl hexanthioate, S-methyl 4-methylpentanoate and theaspirane (≥90%) were purchased from Sigma Aldrich (St. Louis, MO, USA).

HPLC-grade methanol, metaphosphoric, formic, methanesulfonic acid, acetonitrile, ethanol were purchased from Sigma-Aldrich (St. Louis, MO, USA). NaOH, sodium carbonate, and sodium bicarbonate were purchased from Merck KGaA (Darmstadt, Germany).
Standards for phenolic (caffeic acid, caftaric acid, quercetin 3-ß-d-glucoside, quercetin, rutin, hyperoside) and volatile (di-allyl-sulphide-DAS; di-allyl-disulphide-DADS; di-allyl-trisulphide-DATS, di-methyl-sulphide, crotonaldehyde, pelargonaldehyde) compounds were purchased from Sigma-Aldrich (MO, USA).
Glucose, fructose, and sucrose standards were purchased from Chem Service (West Chester, USA); all the other standards were purchased from Sigma-Aldrich (MO, USA). Ultrapure water (18.2 MΩ cm resistivity at 25 °C) was obtained from a water purification system Milli Q (Millipore, Germany).