4 methyl 2 pentanol

To monitor the performance of the GC-MS operating conditions, an external standard (ES) solution was added at the start and end of each GC-MS sample run. The ES was comprised of 1-butanol, dimethyl disulfide, butyl acetate, cyclohexanone, and benzaldehyde (Merck, Ireland) at 10 mg L⁻¹ with 2-phenyl-D5-ethanol (Merck, Arklow, Co., Wicklow, Ireland) added at 5 mg L⁻¹ in ultra-pure water. For the HS-SPME technique, 10 µL of ES was added to the sample in a 20 mL amber La-Pha-Pack HS vial with magnetic screw caps and a silicone/polytetraflurorethylene septa (Apex Scientific Ltd., Maynooth, Ireland); see details in Section 2.3.1. The ES (10 µL) was also added to the TD tube containing the sample extract for both TD and HiSorb (HS-HiSorb and DI-HiSorb), the details of which are described in Section 2.3.2 and Section 2.3.3. To monitor the performance of each extraction procedure, an internal standard (IS) of 2-phenyl-D5-ethanol and 4-methyl-2-pentanol (Merck, Arklow, Co., Wicklow, Ireland) at 20 mg L⁻¹ in ultra-pure water, was added (50 µL) to each WMP sample prior to extraction.

Dichloromethane (DCM), ethanol and methanol (≥99%) Disto-Pesticide residue grade were supplied by Merck (Darmstadt, Germany). Milli-Q^® system was supplied from Millipore (Merck, Darmstadt, Germany). 2-butanol (≥99%), 4-methyl-2-pentanol (99%), 4-hydroxi-4-methyl-2-pentanone (99%), ethyl heptanoate (99%) and heptanoic acid (99%) were used as internal standards for the major compounds analysis, and 2-octanol (99.5%), 3-octanone (99%) and 3,4-dimethylphenol (99%) were used as internal standards for the minor and trace compounds analysis and were purchased from Merck. The chemical standards used in this study were supplied by Merck with a purity of >98%. TDN was synthesized by Synchem UG &Co (Felsberg, Germany) with a purity of 80%.

All reagents, either analytical or HPLC grade, were purchased from Merck (Darmstadt, Germany). The phenol standards (3-hydroxytyrosol, 2-(4-hydroxyphenyl) ethanol (tyrosol), p-coumaric acid, vanillic acid, vanillin, luteolin, apigenin, pinoresinol, p-hydroxyphenylacetic acid (internal standard 1), o-coumaric acid (internal standard 2) oleuropein and caffeic acid), Trolox, fluorescein, and 2,2′-Azobis(2-amidinopropane) dihydrochloride (AAPH) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Volatile standards 4-methyl-2-pentanol (internal standard), ethanol, ethyl propionate, 4-methyl-2 pentanone, butyl acetate, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-octanone, acetic acid, propionic acid, 1-octanol, butyric acid, heptanoic acid, nonanoic acid, (E)-2-hexenal, hexanal, hexanol, (E)-2-nonenal were purchased from Merck. Tocopherols standards were purchased from Calbiochem (Merck). All standards had a purity of 98% or higher.