4 methylstyrene

Styrene (>99%) and all the para-substituted styrene derivatives (4-methylstyrene, 4-fluorostyrene), α-methylstyrene, Palladium (II) chloride (99%) and α,α’-dibromo-p-xylene were purchased from Sigma-Aldrich. 2,4,6-tri(4-pyridyl)−1,3,5-triazine was purchased from TCI Chemicals Pvt. Ltd. Solvents (dichloromethane, chloroform, dimethylformamide, methanol, acetone, n-hexane, ethyl acetate, diethyl ether) were purchased from SD Fine Chemicals. Analytical reagent (AR) grade solvents were used for chemical reactions and HPLC grade solvents were used for spectroscopic measurements. Other chemical reagents like hydrochloric acid, sodium bicarbonate etc. were purchased from Sigma-Aldrich. Heavy water (D₂O; 99.9 atom %D) was procured from Sigma-Aldrich and used as supplied for the chemical reactions as well as for the NMR measurements.

The sample (1.00 ± 0.01 g) was mixed with 1 mL of distilled water and 2 μL of internal standard 4-methylstyrene (8 mg/kg, Sigma-Aldrich Inc., St. Louis, MO) and a small magnetic stirrer were placed in a 20 mL amber vial sealed with an aluminium pressure cap provided with a pierceable silicone septum. The extraction was carried out using the SPME fibre made of divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30 mm, StableFlex, 1 cm long, mounted on a manual support set SPME (Supelco, Bellefonte, PA, USA) [31 (link),32 (link)]. The vial with the sample was placed in a water bath under a specific temperature. After 10 min of equilibrium of the sample, the SPME needle was inserted into the vial and exposed to the headspace of the vial for a specific time. After extraction, the fibre desorption was performed in the GC-MS injection port at 250 °C for 12 min (splitless mode). Blank tests were performed prior to the analysis of the samples to ensure that there was no contamination that could cause memory effects.